01452

SMAL

OPERATOR

SAWMILi;

MANUAL

5">>i~» J*

Agriculture Handbook No. 27

n?' IE î^

U. S. DEPARTMENT OF AGRICULTURE FOREST SERVICE
Agriculture Handbook No. 27 January 1952

Approved for reprinting July 1958

SMALL SAWMILL

OPERATOR'S MANUAL

By C. J. TELFORD, Small Sawmill Specialist

Forest Products Laboratory, Branch of Research, Forest Service

UNITED STATES DEPARTMENT OF AGRICULTURE, WASHINGTON, D. C.

For sale by the Superintendent of Documents, Washington, D. C. Price 65 cents
ACKNOWLEDGMENT

Acknowledgment is made of the assistance given by the following individuals and firms in the form of technical data, advice, and many of the photographs and drawings which appear in this manual: American Sawmill Machinery Co., Hackettstown, N. J. ; Andrus Manufacturers, Eugene, Oreg. ; Atkins,

E; C, and Co., Cincinnati, Ohio ; Bowden, J. E., Alpha, Oreg. ; Chattanooga

Saw Works, Chattanooga, Tenn.; Churchill, George, Drain, Oreg.; Corinth

Machinery Co., Corinth, Miss.; Corley Manufacturing Co., Chattanooga, Tenn.

Crabb Gas Engine Co., Independence, la.; Disston, Henry, Sons Inc., Philadelphia, Pa.; Enterprise Co., Columbiana, Ohio; Forano Co., Ltd., Plessisville,

Quebec, Canada ; Farquhar, A. B., Co., Ltd., York, Pa. ; Fisher-Davis Co., St.

Louis, Mo. ; Foshee, H. B., Jacksonville, Fla. ; Frick Co., Waynesboro, Pa. ; Fuglie, E. A., Winona, Minn.; Gordon Hollow Blast Grate Co., Greenville, Mich.;

Hallock, Hiram, Madison, Wis. ; Hanchett Co., Big Rapids, Mich. ; Hart Bros.

Machinery Co., Clarksburg, W. Va. ; Hoe, R., and Co., Inc., New York, N. Y. ;

Howell R. R., and Co., Minneapohs, Minn. ; Ireland Mill and Supply Co., Cayuta,

N. Y. ; Jackson Box Co., Black River Falls, Wis. ; Jackson Harvester, Inc., Brewton, Ala.

Lane Manufacturing Co., Montpelier, Vt. ; Mater Machinery Corp., Corvallis, Oreg. ; Mill Engineering and Supply Co., Seattle, Wash. ; Olsen, Leslie, Mora,

Minn. ; Peters Co., Portland, Oreg. ; Sawmill Equipment Co., Inc., Kelso, Wash. ;

Simonds Saw and Steel Co., Fitchburg, Mass. ; Sinker Davis Co., Indianapolis,

Ind. ; Sumner Iron Works, Everett, Wash. ; Topping, Floyd, Wild Rose, Wis. ;

Wheland Co., Chattanooga, Tenn.

C.'.

^^^'à^i\OtQ\.

n
TABLE OF CONTENTS

Pace

Introduction . 1

Purpose and scope 1

Safety measures 1

Types of small sawmill headrigs 2

Sash-gang headsaws 2

Band headsaws 3

Circular headsaws 3

Sizes of headrigs 4

Husk and mandrel 7

Headsaw guides 9

Rolls and spreaders 9

Peed works 9

Carriages and trackways 14

Setworks and receders 15

Dogs , 21

Edgars 25

Trim and cut-off saws 26

Log turners 30

Metal detectors 33

Conveyor systems 34

Sawdust chains 34

Sawdust blowers 34

Dead rolls 35

Live rolls 35

Belt conveyors 36

Chain conveyors 37

Trash-disposal systems and methods 37

Power and transmission equipment 39

Horsepower requirements 39

Classification of prime movers by types .... 41

Basis of horsepower ratings 41

Comparison of types of prime movers 42

Variants of each type of prime mover 42

Dutch-oven furnaces for burning sawdust ... 42

Belts and pulleys 44

Flat belts 44

V-belts 45

Transmission capacity of belts 45

Pulleys 47

Shafts and bearings 48

Care and maintenance of saws 48

Sawteeth 49

Factors affecting selection and operation of

saws 50

Saw speed and chip thickness 51

Tensioning the saw 52

Alinement of saw and teeth 55

Page

Care and maintenance of saws—Continued

Filing circular ripsaws 56

Filing circular crosscut saws 58

Labor requirements for small sawmills 59

Work distribution by crew size 60

Mill layout 61

Log yards and ponds 61

Lumber yard layout 63

Piling and sorting lumber for air drying ... 64

Dipping tanks 71

End coatings 71

Sample plans of mill layouts 73

Setting up an unsheltered ground mill according to plan 1 73

Building plan and machine location for sheltered portable mill according to plan 2 . . . 75

Building plan and machine location for semipermanent tie mill according to plan 3 . . . 77

Building plan and machine location for semipermanent lumber mill according to plan 4 79

Building plan and machine location for permanent heavy mill according to plan 5 79

Load-out equipment 83

Car and trackway 83

Lumber props 83

Rolls 83

Loading scaffolds 84

Sliding skids 84

Trucks and rails 86

Pork-lift trucks 89

Mill operation 89

Milling softwood logs 89

Milling hardwood logs 91 , Sawing oversized logs 97

Size standards 98

Tallying and grading 102

Some business aspects of small-mill operation . . 103

Capital requirements 105

Marketing 105

Accounting 106

Public regulations affecting sawmills 110

Scaling and grading logs Ill

Log scaling Ill

Log grading 112

Organizations issuing grading rules 113

Glossary 114

Index 119

III
INTRODUCTION

Small sawmills are an integral part of our

lumber-manufacturing industry. No important

lumber-producing region of the United States

is without them. They perform several essential functions, not the least of which is the

economical production of lumber under conditions that make it impractical to operate large

mills. With small capital investment and low

operating costs, they can supply local needs

from locally grown timber ; yet they contribute

importantly to the lumber supplies of metropolitan areas. They also fill an economic need

in regions where large mills nourish, serving

as auxiliaries that utilize timber of sizes and

kinds not suitable for the large mills.

The need for improvement in small sawmill

operation has long been recognized. At the

request of the Chief Forester in 1926, a unit

was set up at the Forest Products Laboratory

to investigate means of improving the operating efliciency of small sawmills, particularly

those operating on the National Forests and

farm woodlands. As part of its program, this

unit has assisted extension agencies in conducting schools for sawmill operators and has

published recommended practices for definite

phases of small-mill operation. In order to

stimulate lumber production during World War

II, a short bulletin (U. S. Department of Agriculture Misc. Pub. 509) was published for

guidance of small-mill operators. The present

manual is an amplification of that bulletin and

other publications issued as a part of this program.

Many different types of sawmill equipment

are described and illustrated in this manual, in

order to provide operators with a reference

source as an aid in selection, as well as to portray mechanical principles controlling the functioning of parts as an aid in correcting faulty

mechanisms, and to provide guidance in the

construction of certain items which can be

made by or for the individual operator. Permission has been given by manufacturers for

the use of photographs of certain sawmill

features which are undoubtedly protected by

patent rights. The reader should be aware that

publication in this manual does not constitute

a justification for copying features so as to

infringe on patent rights in any manner.

There is no hard-and-fast rule differentiating

"small" from "medium" and "large" mills.

Sawmills of the United States range from

3,000 to 300,000 board feet in 8-hour production capacity. For purposes of this bulletin,

mills producing up to 20,000 board feet per 8-

hour shift have been classified as small. This

dividing line is low for certain west coast mills ;

but elsewhere in the United States, the majority of the mills operating today fall well

within this limitation.

Purpose and Scope

This publication is intended to serve as a

handbook for operators of small mills. It deals

mainly with the types and variations of equipment available, installation of equipment, and

operational techniques, especially for mills of

the circular head-saw type. The purpose is to

furnish operators with a reasonably complete

and detailed evaulation of various types of

machinery and handling equipment, so that the

general standard of operation may be raised by

reducing costs, preventing wastes, and improving the quality of the lumber.

Although logging is ordinarily an inseparable part of small-mill operations, it is not

covered in this handbook. Brief treatment is

given such important segments of mill management policy as buying and selling; inventories

of timber, logs, and lumber; selection of sales

outlets, and extension of credits.

Safety Measures

Although outside the scope of this publication, reducing the hazards in sawing and

machining lumber is one of the most important

steps in sawmill operation. Statistics clearly

show that sawmilling is one of the most hazardous occupations. Familiarity and compliance

with State regulations and with responsibilities

under workmen's compensation acts are essential in sawmill design and management. This

publication does not attempt to deal with specific safety measures because sawmill safety is

a subject in itself and requires fuller treatment

than can be given here. Other publications

must be relied upon for detailed information on

safety measures.

Some of the literature on safety provisions

in sawmill operation consists of the Logging

and Sawmill Safety Code, National Bureau of

Standards Handbook No. 5, and special subject

matter that can be procured through the

National Safety Council, Chicago, 111.
TYPES OF SMALL SAWMILL HEADRIGS

For the purposes of this manual small sawmills are classified according to the type of

headsaw employed. There are three distinct

types of sawmill headsaws, circular, sash-gang,

and band. Variations of the circular-headsaw

type are the single-circular with or without a

circular top saw; the twin-circular; and the

gang-circular. All are used in small mills, but

numerically the single-circular dominates almost to the exclusion of the others. Following

brief descriptions of the sash-gang and band

types, major emphasis will be given to circular

mills. Figure 1 shows a typical circular sawmill.

Progressive operators search for methods

and equipment to improve quality and lower

product costs. The objectives sought for headsaw equipment may be listed as (1) maximum

recovery of lumber from the log, (2) recovery

of maximum qualities on a grade and thickness basis, (3) accurate sizing, and (4) minimum labor and machine costs per thousand

board feet. None of the three general types of

headrigs excels in attaining all four objectives.

Sash-Gang Headsaws

The sash-gang ranks high as a headsaw in

the quantity of lumber recovered and in cutting accuracy, but relatively low in the grades

of lumber recovered and in flexibility for cutEYE-LEVEL

SCALE BOARD

12 - PAWL GEARED SETWORKS

SET-OUT ATTACHMENT

SLAB ROLLER AND SPLITTER

FLANGED COUPLING ON SET SHAFT

ROLLER BEARING

^SIDE-OPERATING DOG

HEADBLOCK BASE

MAIN BELT

TIGHTENER

MANDREL

DRIVE PULLEY

DOUBLE BELT FEET

AUTOMATIC FOOT

RECEDER PEDAL

FIGURE 1.—Small circular sawmill equipped with headblock type of small-mill carriage.
SMALL SAWMILL OPERATOR'S MANUAL

ting to various thicknesses. The operating cost

per thousand board feet is medium to low on

properly installed and organized units. It has

long been looked upon with more favor in certain foreign countries, such as Sweden, Finland,

Germany, and New Zealand, than in the United

States. This is due in part to the character of

timber and lumber markets, and in part to the

fact that foreign operations are usually planned to take maximum advantage of the characteristics of the round-log gang headrig.

By making use of the carriage mechanism,

which permits sawing with the sweep of a log

instead of in a straight line, the percentage of

short, thick slabs cut from crooked logs can be

substantially reduced. It is questionable if the

round-log sash-gang mill will ever be adapted

for use in the United States as widely and

advantageously as in some other countries.

In the United States, the sash-gang saw is

successfully used on knotty Douglas-fir and

similar softwood logs up to approximately 34

inches in diameter. The saws are usually set to

cut flitches 4 inches thick from the midsection

and 2 inches thick from the outer faces ; these

flitches are edged and usually resawed to 1- and

2-inch products. Production rates up to 10,000

board feet per hour are achieved in large logs

when the sash-gang headrig is combined with

a heavy edger and resaw.

A second set of conditions for successful

sash-gang operation prevails where small logs

potentially low in grade outrun are sawed for

box lumber and kindred products. One sashgang unit slabs and saws one or more boards

from two opposite faces. The cant then is reduced to lumber in passing through a second

unit. Logs are sorted into groups according to

their diameter. The saws of the first sash-gang

are set to minimize slab waste for logs of one

group and must be reset for logs of any other

group. This system gives efiicient quantity

recovery and lowers edging costs. A variation

of this system consists of a standard circular

or band headrig with which the higher-quality

material or random thicknesses can be recovered but which also provides slabbed cants for

the sash-gang.

Sash-gang headsaw production rates on

small logs approximate 6,000 board feet per

hour. American practice is to use saws taking

a 9/64-inch kerf; elsewhere kerfs down to

7/64 inch are taken. One requisite for successful installation is that foundations be firm

enough to withstand the repeated shocks of the

up-and-down thrust of the gate. Sash-gang

headrigs have been used as mobile units when

mounted on heavy skids or on a specially

designed chassis. Those on chassis are set on

firm foundations at the sawing site.

Band Headsaws

The band headrig ranks high in recovery

by grades and allows ready change in thickness

cut. It ranks medium in quantity of material

cut and in accuracy of cut. Labor and machine

costs per thousand board feet are medium to

high. This machine is relatively expensive to

install and maintain. Its logical field is in operations assured of timber supplies adequate to

amortize the relatively high installation costs,

and it is most efficient with logs in sizes and

grades justifying a high-cost but flexible headrig. The small band saw is economical to

operate only where production rates approach

20,000 board feet or more per shift. Band mills

mounted on skids or wheels have not proved

practical enough to meet competition of other

types of headrigs. Production rates vary

greatly with log size and supplemental equipment. A single band saw cutting medium-size

logs normally produces from 3,000 to 4,000

board feet per hour.

Circular Headsaws

The circular headrig ranks high in flexibility for cutting lumber of highest grade and

thickness values, but medium to low in production of all grades of lumber and in sizing

accuracy. Labor and machine costs per thousand board feet are medium to high, on the other

hand, installation and maintenance costs are

relatively low. Circular headrigs have been successfully mounted on wheels. In combination

with the lower degree of skill required to maintain and operate them, these advantages give

circular headrigs a competitive advantage in

operations not assured large supplies of timber.

The kerf loss due to the relatively thick

saws used in America is minimized in Norwegian mills equipped with saws taking kerfs

down to three thirty-seconds inch on the relatively small logs sawed. Development trends in

America have been directed toward increasing

output per man-hour. Mills are available on

which, by use of mechanical, hydraulic, electric,

or air-powered controls, the sawyer directs

from a fixed position the progress of the log on

the deck and to the carriage, as well as the

dogging, setting, and turning operations and

the movement of the log through the saw and

back. This development has possibilities for

producing cheaper and more accurately sized

lumber on small mills. Progress in kerf reduction lags behind European standards.

Twin-circular saws are limited to cutting

of relatively small logs, but the characteristic

of variable spacing between saws adapts such

equipment to cant or tie production. Gang-
HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

circulars, with saws fixed, are comparable to

sash-gangs in that they reduce an entire log to

boards in a single passage. Gang-circulars take

a heavier kerf and are less accurate in sizing,

but the problem of making mobile equipment

is simpler with them than with sash-gang

equipment. The gang-circular with saws passing through a stationary log may be developed

to give better-sized products and readily lends

itself to mobility because of its short over-all

length.

Sizes of Headrigs

Band headsaws are classified as to size by

the diameter of the wheels. Their size ranges

from 31/2 to 11 feet in diameter for 19- to

12-gage saws. For small mills, the wheels range

from 31 ó to 6 feet in diameter, and the saws

from 17-gage, 8 inches wide, to 15-gage, 12

inches wide (fig. 2).

Sash-gang headsaws are classified as to size

on the basis of the inside width of the gate

through which the log passes. This size range

is from 24 to 36 inches. The log is brought to

M-84348-F

FIGURE 2.—Six-foot band headrig.

M.82124-F

FIGURE 3.—Round-log sash-gang headrig.

the infeed rolls on the bunks of two separate

trucks running on rails (fig. 3). The rear truck

has a mechanism for alining the log with the

saws. To assure that the log will not twist in

the rolls, either a rosser is placed slightly ahead

of the bottom infeed roll to plane a flat-bearing

surface, or two adjustable guide plates about

6 inches apart engage two saw lines of a series

of the emerging boards. Feed rates of 6 to 20

feet per minute are controlled by means of

gears. Saws are about 14-gage, with a kerf

approximating five thirty-seconds inch.

The single-circular headsaws are not readily classifiable on a size basis (fig. 1). Mills

using them are made by dozens of manufacturers and vary greatly in size and design. The
SMALL SAWMILL OPERATOR'S MANUAL

smaller ones use saws of 36-inch diameter, and

weigh from 1/2 to IVi tons, including husk,

track, and carriage; the largest can take a

6-foot-diameter saw, or a 66-inch main saw and

a 40-inch top saw, and weigh in excess of 6

tons. The weight classification given in table 1

lists dimensions for key parts that are characteristic of, but not necessarily limited to, the

particular weight class cited.

The single-circular saw has been successfully mounted on either a pneumatic-tired reinforced trailer body or special framing suspended from a single axle. Mounted on a trailer

body, it is the typical small circular mill with

trackway outside of the saw; if it is mounted

on a single axle, the trackway passes over the

mandrel. The single-axle mount is used either

with the sawyer riding the carriage, which

passes over small rollers fixed to the mill framp

(fig. 4), or with the sawyer at the usual ground

position and the carriage equipped with small

wheels (fig. 5). In either case, the power unit

is placed on the separate truck used to transport the equipment. Variations built by individuals have included a two-axle trailer with

the power unit mounted directly over the saw.

Wheel-mounted mills are relatively efficient

where frequent moves are involved, as in cusTABLE 1.—Size characteristics of various classes

of circular-headsaw mills

Mill class (by weight)

Item 3,000

pounds

and

less

3,100

to

4,500

pounds

4,600

to

6,000

pounds

6,100

pounds

and

heavier

Mandrel diameter

Width of feed belt

Headbloek openings.__

Maximum size of saw

recommended

Maximum log diameter taken

Iriches

3

33

54

32

Inches

m

4

36

56

33

Inches

2%

5

40

60

36

Inche.'

6-h

48

'66

55

With 40-inch top saw.

FIGURE 4.—Single-circular mill, wheel-mounted. Sawyer rides the carriage.
HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

FIGURE 5.—Single-circular, wheel-mounted mill. Sawyer stands on the ground.

M-82123-F

FIGURE 6.—Twin-circular headrig. Saws not shown.

M-B230B-F
SMALL SAWMILL OPERATOR'S MANUAL

torn sawing for farmers or on commercial

operations where it is feasible to bring the mill

to the trees.

Twin- and gang-circular saws are used for

very small logs. Twin-circulars have a separate

mandrel for each saw, the saws can be given

lead, and spacing between them is controlled

by a sawyer-operated lever to produce stock of

desired thickness (fig 6). The saws in one variant are moved along a keyway on the mandrel,

in another they are fastened to the mandrel

and the assembly of driven pulley, mandrel,

and saw is moved by the control lever. The log

may be fed to the saw by means of a continuous chain, with return ahead of the saws ; or by

means of a narrow, continuous chain with lugs,

which may pass between the saws. A top roll, or

floating block, may be employed to steady the

log. Gang-circular saws are fixed to a single

mandrel, the spacing between saws being controlled by means of fixed collars. Some units add

a series of topsaws on a separate mandrel. In

one variant (fig. 7), feed is by means of a continuous chain; in another, the log is held stationary in chucks and the saws pass through

the log (fig. 8).

A special combination of circular and band

saw, called a splitter-resaw, is sometimes used

for making box and similar lumber from small

logs. The circular saw is centered in a trough

so as to split the logs as the lugged chain carries them through (fig. 9). The halved logs

pass to a horizontal resaw equipped with return

and outgoing conveyors. Usually three pieces

can be fed to a double-bed resaw at a time

(fig. 10). Production rates are relatively high

in small logs, approximating 3,000 board feet

an hour. The installation costs are high, manhour requirements low, and precision of sizing

medium to low.

HUSK AND MANDREL

Band mills have heavy metal frames supporting the shafts and other mechanisms.

Circular mills have a box-like frame of wood or

metal called a husk, that supports the mandrel

and usually the feed-works mechanism. Circular-mill husks vary but slightly in the different

models. Two bearings are usually provided for

mandrels up to 6 feet in length, and additional

ones are added for longer mandrels. With top

saws, three bearings are usually used and a

metal top-saw frame is added. Provision is

usually made to fix the husk to sills with bolted

metal brackets; in some models, brackets are

also used to hold the track and husk in a fixed

relationship.

Wood husks, because of their lesser weight,

meet the needs of mills that are frequently

moved; metal husks are more suited to semipermanent installations. Brackets connecting

the husk with the mills to maintain the proper

relationship between husk and track are good

features.

The mandrel, or arbor, is the expertly

machined, hardened-steel shaft carrying the

saw and, usually, several pulleys ; sometimes it

has a fiywheel also. Sizes vary, the diameter of

the light-duty types being as little as 2-3/16

inches and that of the heavy-duty types 4

inches or more. Standard lengths range between 4 and 10 feet ; extensions can be coupled

to any length. The mandrel is commonly beltdriven, but direct drives are also used. Clutches

are sometimes placed in the mandrel, so that

the saw can be shut down independently of

other machines; or the edger-drive pulley on

the mandrel may have a clutch that permits

the operator to stop the edger without halting

the headsaw.

The saw is clamped between a fixed saw

collar sealed to the end of the mandrel and a

loose collar held by lug pins and bolted on the

mandrel. The standard saw has a 2-inch eye

with two %-inch lug-pin holes equally spaced

on a 3-inch circle. Mandrels have babbitt or

roller bearings, and provision for adjusting the

mandrel for saw lead is made with set screws

that press on a pivoted bracket of the bearing

nearest the saw. Roller bearings are superior to

babbitt bearings. End play in the mandrel is

prevented by one of three methods: (1) By

means of conical roller bearings ; (2) with babbitt bearings, by means of a shoulder around

the mandrel that is seated in a groove in the

bearing nearest the saw; or (3) by means of

collars on the mandrel where it enters the bearing housing.

Requirements of a satisfactory mandrel are

a diameter adequate to carry the load, enough

length to place the pulleys, bearing supports

to hold it in line, and saw collars that uniformly

contact the saw in a plane at right angles to the

mandrel axis. A space approximating threesixteenths inch should separate the fixed collar

from the first bearing box; if closer, grit is

likely to collect and heat the mandrel.

In the usual arrangement of bearings and

pulleys on the mandrel, a bearing is between

the saw collar and the mandrel pulleys that
8 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

Um&ÊÊimiaÊr''-m^

M-S2946-P

FIGURE 7.—Gang-circular headrig with topsaws.

M-980B0-F

FIGURE 9.—Circular saw of splitter-resaw combination.

M-82122-F

FIGURE 8.—Gang-circular with saws feeding and

log stationary.

M-9S079-F

FIGURE 10.—Horizontal band saw of splitter-resaw

combination.
SMALL SAWMILL OPERATOR'S MANUAL 9

operate the feed mechanism (steam-piston,

electric, and hydraulic feeds excepted), with a

second bearing between them and the driven

pulley. If the edger is driven oif the mandrel,

the drive pulley of the edger is beyond the second bearing and a third bearing is between the

edger pulley and the driven pulley of the

mandrel. Flywheels weighing up to 6Ö0 pounds

can be placed between the drive pulley for the

edger and the third bearing; heavier ones

should have bearing supports on each side.

Direct drives are occasionally used on headsaw hookups. Usually they require a speed

reducer, a flexible coupling, or a universal

joint. When saws are jammed on metal or

otherwise, they are likely to be severely damaged if direct-driven.

HEADSAW GUIDES

Circular-headsaw guides, which steady the

saw, are placed so that the pins touch the saw

about 2 inches below the level of the carriage

bolsters on the front edge of the saw and onefourth inch inside the gullet. These are sometimes supplemented with guides at the back or

engaging the top of the saw. Top guides must

be quickly removable in case the saw is buried

in the log.

Guide pins are usually made of wood but

occasionally of leather, and may have provision for self-oiling, although ordinarily they are

not oiled. All models make provision for adjusting the guide pins within the frame so that

they contact the saw blade, for adjusting the

frame so that the gap coincides with the plane

of the saw, and for readily swinging the arms

out of the way when changing saws. Models

may exhibit minor variations ; for example, the

pin-holding arms may be independently adjustable instead of in one piece (ñg. 11). Guide

equipment should have a deep, wide throat to

M-82194-F

FIGURE 11.—Saw guide with pins independently

adjustable.

insure the removal of sawdust and small particles that otherwise may give trouble if they

become deflected against the sawyer or lodged

in equipment.

ROLLS AND SPREADERS

standard equipment on most circular mills

are a roll or bar attached to the husk ahead of

the saw and a spreader and roller immediately

back of the saw. The bar steadies the cant and

expedites its passage into the saw ; the spreader

and roller keep the board from binding the saw

and expedite its passage. Usually spreaders are

disks that are flat on the log-side face and

beveled to a thin edge from the board-side face.

Many operators replace this disk with a

spreader shaped like a scythe blade and curved

to parallel the perimeter of the saw. Knife-type

spreaders are required by some State safety

codes.

FEED WORKS

Small-mill feed mechanisms, by which the

sawyer controls the rate of log feed to the headsaw, are operated by (1) straight friction; (2)

friction combined with belts and pulleys; (3)

belts and pulleys; (4) belts, pulleys, and

clutches; (5) gears and clutches; and (6) electric, hydraulic, or steam-piston drives. All may

use the rope drive (cable over drum). The second type of mechanism sometimes substitutes

the rack-and-pinion drive. One variant of the

steam-piston drive transmits power through a

shaft fastened to the carriage.

In straight friction types, beveled plates

powered by the mandrel operate a beveled friction wheel and shaft that rotate a disk continuously. By bringing the rim of a lever-
10 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

actuated friction wheel into contact with this

disk, motion is transmitted through shafts and

gears to turn the drum and move the carriage.

Reverse motion is obtained either by crossing

the disk center with the friction-wheel contact (fig. 12, A) or by contacting the reverse

face of the disk with a second friction wheel

after breaking contact with the first one (fig.

12, ß).

vrOfft/«

FIGURE 12.—Straight friction types of feed works

A, Gigback obtained with lever by shifting friction

wheel to opposite half of disk. B, Gigback obtained

by disengaging one and engaging the other friction

wheel with the lever-controlled mandrel disk.

In the types employing friction with belts

and pulleys, power is transmitted in one of

three ways: (1) From a pulley or sprocket

fixed to the mandrel through a belt or chain to

a pulley or sprocket shafted to a friction wheel

that is lever-actuated to contact a bull pulley

shafted directly to the drum (fig. 13, A); (2)

from the drive pulley on the mandrel by belt

to an intermediate pulley, which is shafted to

a sprocket transmitting power through the

chain to the drum shaft (fig. 13, B) ; or (3)

from the drive pulley on the mandrel by belt

to a second pulley equipped with an enlarged

hub and wide rim (fig. 13, C). A friction pulley

is placed between the hub and rim (fig. 13, C)

on a movable shaft connected to the drum, and

feed action results from engaging the hub face

while gig action results from engaging the inside of the rim. Both feed and gigback can be

obtained by the feed works shown in figure

13, D.

In the types employing belts and pulleys,

the power for feeding the carriage is transmitted by belt from a pulley fixed to the mandrel to

a lever-actuated movable pulley ahead of the

mandrel, and thence through a fixed pulley

behind the mandrel and the fixed pulley on the

drum shaft. Power for reverse motion is transmitted by belt from a second pulley fixed to

the mandrel to a second pulley fixed to the

drum shaft. A lever-actuated rider is so adjusted in a rocker-arm frame that one belt can

be tightened and the other loosened by moving

the lever to feed or gig position, as desired

(fig. 14).

The type employing belts, pulleys, and a

clutch has the same hook-up as the type with

belts and pulleys alone, but the belts are tight

in order to rotate the two pulleys continuously

on bearings about the drum shaft or a shaft

geared to the drum shaft. Drive or gig is provided by contacting one disk or the other fixed

to each of these pulleys with a corresponding

disk fixed to lever-actuated pulleys sliding

along a key seat on the drum shaft (fig. 15).

In the type operated with gears and clutch,

power taken from the mandrel through chain

sprockets drives a floating axle and, by means

of planetary gears and a drum-brake mechanism, turns the drum shaft (fig. 16).

In electrically powered feeds, the drum is

usually installed near the deck end of the track

and a reversible direct-current motor is connected to it. Rod connections from the sawyer's

lever to the transformer control the direction

of rotation and speed attained by the motor.

Hydraulic feeds employ at least three variations in power transmissions: The turbine,

the oil motor, and the single piston. In the turbine, oil under pressure from power usually

taken off the mandrel is forced through the

turbine blades, thus turning a shaft connected

to the drum (fig. 17).

In the oil motor, a series of small pistons

are radially placed on a rotating cylinder that

is concentric with a fixed core that contains

oil ducts (fig. 18). The piston heads are contained by an outer ring placed eccentrically to

the core and free to turn on its axis. The inlet

oil vents are so placed that oil under pressure

is simultaneously forced into several consecutive pistons during one-half of a complete cycle

of the cylinder, and withdrawn during the
MANDREL

DRUM

MANDREL

FULCRUM

DRUM

SMALL SAWMILL OPERATOR'S MANUAL

n

11

SLIDING BEARme

DRUM

mNDREL

FULCRUM

MANDREL

DRUM

FULCRUM

FIGURE 13.—Friction-belt-pulley feed works. A, Eccentric rocker lifts one friction wheel free when the other is

brought in contact with friction wheel in drum shaft to reverse action. B, Belted mandrel pulley reverses drum

shaft from direction caused by large friction pulley. C, Drum reversed by shifting rider pulley with lever from

hub to rim of belt-driven drum pulley. D, Lever-controlled bull wheel reverses drum shaft as it engages one or

the other of belt-driven pulleys, which turn in opposite directions.

other half of the cycle, and oil is closed from

the circuit during the longest and shortest

phase of the piston stroke.

To start the motor, oil under pressure enters

the series of pistons, so that each piston head is

thrust against the eccentric containing ring.

Since the pistons are not radial to the ring,

the direction of thrust is not along the radius

of the outer ring ; thus, one of the components

of this force is tangential to the ring and

acts in the direction of increasing divergence

of the circumferences of the eccentric parts.

This tangential force rotates the pistons about

their common axis, and this rotation is transmitted to the output shaft. Reverse direction

results from reversing the direction of oil

under pressure; speed is controlled by varying

the volume of oil supplied under pressure to the

motor. Oil pressure is provided by a duplicate

piece of equipment, the radial pistons of which

are turned from a power source.

In the single-piston variant of the hydraulic

feed, a cylinder having a length approximately

one-half the distance of carriage travel is

anchored between the rails. One end of a cable

is attached to the cylinder mount at a in

figure 19, and the cable is brought over one

pulley of a double sheave attached to the end
12 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

FIGURE 14.—Belt-pulley feed works. Lever action tightens one belt while the other runs slack, thereby driving drum in one direction or the other.

FIGURE 15.-

FULCRUMS

-Belts-driven feed works with clutch.

FIGURE 16.—Chain-driven feed works with lever-controlled brake bands on split housings. Chain drive

rotates hollow shaft within which drum shaft floats

freely. When brake band on one housing is loosened

by lever, brake band on the other housing is tightened. Rotation of hollow shaft is transmitted to

housings through planet gears to inner side of housing rim. Housings rotate drum shaft through pin

engaging housing with shaft.

!JE^r' 'mtyitiidi

w^

"""^ « ',-; ; r>' !• «SB»*.. :f •^'- i

^.„11 ., ilm^ÊÊÊkv:;^Skr"iiiiJBS9«

^y^5 jJP^'^MHm

'11, .

Ifi

. -k. -

ml ' ^'^^^^^H

1 ^^ ^^'"•^

FIGURE 17.—Hydraulic feed works, turbine-driven.

• * •

M-82309-F

FIGURE 18.—Oil motor used for hydraulic feed works.

of the piston rod and over a second sheave

anchored at the deck end of the track and

thence fixed to the front end of the carriage

frame at b of figure 19. One end of a second

cable is anchored at the opposite end of the

trackway, point e of figure 19, passes over the

other pulley of the double sheave fixed to the
SMALL SAWMILL OPERATOR'S MANUAL 13

FIGURE 19.—Hydraulic feed works. Cable anchored at

a passes over double-sheave pulley mounted on end

of piston, over pulley at deck end of track, and to

front end of carriage frame at b. Cable anchored at

e passes over piston pulley and pulley at c to back

end of carriage frame at d. Piston action thus pulls

carriage back and forth twice the length of the piston stroke.

end of the piston rod, thence over a sheave

anchored at the nondeck end of the trackway,

and is fixed to the back end of the carriage

frame (fig. 19). By this means, the carriage

travels twice the distance represented by the

movement of the piston.

In one feed system driven by steam pistons, the twin-engine feed, piston heads in two

short cylinders deliver power through connecting rods to turn a crankshaft directly connected or geared to the drum (fig. 20). In

another system, the shotgun feed, a piston head

in a single cylinder that extends the full

distance the carriage travels is connected by a

piston rod directly to the carriage (fig. 21). In

the twin-engine feed, a lever controls the direction of rotation and size of valve opening. In

471449°—58—2

FIGURE 20.—Two-cylinder steam feed works.

the shotgun feed, the lever controls the intake

and exhaust at each end of the cylinder so as

to apply steam pressure to either face of the

piston head and thereby advance or reverse

the carriage.

In all except the steam piston, electric, and

hydraulic types, the feed works is geared to

recede the carriage about twice as fast as it

advances it. On all types, the sawyer seeks to

adjust the rate of advance to the load capacity

of the saw or power source.

The rope-drive and single-cylinder feeds

(hydraulic or steam) have the advantage that

they can be centered on the carriage, thus minimizing strains in the frame. The rope drive

can be extended more readily to saw long logs

than can the single-cylinder variant. The rackand-pinion drive, applying the propelling force

along the edge of the carriage, is more subject

to racking, and the carriage travel is limited

by the length of the rack fixed to it. This drive

therefore is less suited to cutting long logs.

In the straight friction mechanism, the

braking action and power transmission are

dependent upon the friction where the wheel

and disk are tangent; considerable leverage

must be used, and the carriage is braked into

reverse by holding the friction wheel in static

contact with the moving disk, thus tending to

wear flat spots in the friction wheel. Carriage

reverse is normally sluggish. In the belt-andpulley type, braking action and power transFlGURE 21.—Single-cylinder steam piston feed works.
14 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

mission are dependent on the contact of belt

and pulley over areas approximating one-half

the circumference of the pulley; consequently,

wear is dispersed over a greater area, and a

quicker response to the lever is possible. In the

type employing friction, belts, and pulleys, the

continuously rotating friction wheels tend to

wear more uniformly and exert a quicker response than in the straight friction type. The

type using belts, pulleys, and clutch and the

planetary-gear type exert a quicker response

and action than does the type using friction,

belts, and pulleys; moreover, then can be used

where steam is not available, and are suited to

mills producing 2,000 board feet or more per

hour.

Steam-piston, electric, and hydraulic types

combine speed with excellent control, and are

used on mills with a capacity of 2,000 board

feet or more per hour.

CARRIAGES AND TRACKWAYS

Carriages used on band mills are usually

more complex and of heavier construction than

those on mills having circular headsaws. In the

single-cutting type of band mill, they provide

for offsetting the carriage on the gigback to

clear the band saw. They are usually supplemented with power log turners, for which they

must be strongly constructed. The V-track is

usually farthest from the saw.

Small-mill carriages may be classified as of

either the headblock (fig. 1) or log-beam type

(fig. 22). Below the bolsters they are alike

in that frames range in width between 2 and 4

feet and in length between 12 and 24 feet. The

wheels, ranging from 6 to 14 inches in diameter, depending on the model, are outside or

directly under the side members at approximately 5-foot intervals. All wheels may be

flanged or those on the track nearest the saw

may be flanged and the other series not. Axle

bearings may be babbitt or roller. In the headblock type, two or more bolsters are fastened

to the frame ; if two, they are equidistant from

the midpoint and spaced to support the shortest

log encountered; if there are more than two,

one is usually placed within 2 feet of the front

and another 2 feet from the back, with the rest

in between.

In the log-beam type, the upright members

(knees, dogs, offsets) are fixed to a beam extending the length of the carriage. This beam

and uprights are advanced or receded by setworks that are either attached to the beam

with racks fixed to the carriage frame, or atFlGURE 22.—Log-beam type of small-mill carriage
SMALL SAWMILL OPERATOR'S MANUAL 15

tached to the carriage frame with the racks

fixed to the beam. Two or more racks are used,

and additional support is given to the beam by

bolsters at 3- or 4-foot intervals. Knees and

dogs can be placed at any interval along the

wood beam.

The carriage should carry the log past the

saw in an unvarying, straight line, should support the log against any turning or vibration,

and should be sturdy enough to sustain the

stresses and shocks of normal service.

Side play of the carriage is eliminated by

means of flanged or grooved guide-rail wheels

and by boxing the wheel bearings with axle

collars. For accurate sawing, guide-rail wheels

must have no lateral play on the axles; those

on the nonguide rail, however, should be free

in this respect. For mills using powered log

turners, the guide rail is the one farthest from

the saw. There is less chance that trash will

collect on this rail than on the other one. The

common types of guide rails are shown in

figure 23.

A BCD

FIGURE 23.—Four variants of guide rails. A, Oval-head

rail; B, T-rail; C, beveled T-rail; D, beveled bar rail.

Bolsters are usually formed from channeliron, I-beam, or similar patterns. The base of

the knee rides on the bolster, and the friction

surfaces of each may be planed. The knee does

not vary greatly among different makes of

mills; it is essentially a sturdy upright, the

base of which extends nearly across the carriage. The rack is ordinarily centered under

the base of the knee, but in some models is

offset outside of the bolster. In some models,

the rack is adjustable. When boss dogs are

used, the upright of the knee is a housing for

the boss-dog mechanism and the knee face is

slotted so that the dogs can function through

it. Movable bars, variously known as set-out

blocks, taper bars, taper knees, offsets, or false

knees, are commonly bolted to the knees, so

that the back supports can be advanced to conform with the taper or crook in the log. These

are basically as shown in figure 24.

FIGURE 24.—Set-out block bolted to knee, lever-actuated.

Bolsters should support the log within 2

feet of the extremities to minimize vibration;

thus, two bolsters with an over-all spacing of 8

feet are inadequate for logs longer than 12 feet,

and three spaced 6 feet apart, 12 feet over-all,

are inadequate for logs longer than 16 feet. As

the front and rear bolsters are farther from

the ends of the carriage than the trucks, the

over-all length of the carriage will be approximately 4 feet in excess of the over-all spacing

of the bolsters. The width of the carriage must

be adequate to permit a knee opening to take

and support the larger logs. For medium-size

logs a carriage width of 3 feet is suggested, and

for large ones a width of 44 to 48 inches.

Welded metal carriages are heavier than wood

ones of like size and can stand heavier shocks.

The log-beam type of carriage usually has more

bolsters than the headblock type, and additional

dogs can be placed anywhere along the beam.

SETWORKS AND RECEDERS

The function of the setworks is to advance

the log quickly toward the saw line by intervals accurately held to the thickness being cut,

and to reverse the knees speedily. Precision in

reversing is not vital.

The mechanism by which the knees of small

mills are advanced may be lever-operated or

power-operated. They may be receded by lever,

by springs, or by power-actuated devices.

To advance the knees in lever-operated equipment, the toothed rim of the set wheel fixed to

the set shaft is engaged by pawls attached to

the lever (fig. 25). A pull on the lever is transmitted as a turn on the set shaft to the pinion

wheel fixed to the shaft at each knee. The

pinion turns in the rack of the fixed bolster and

advances the knee. A full throw of the lever

advances the knees approximately 21/2 inches.

With single-acting levers, the knees are advanced by forward lever movement only (fig.

25, ^). With the double-acting type (fig. 25, ß)

knees are advanced on the back stroke as well,

through a second set of pinions or pawls below

the fulcrum of the lever arm.
16 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

FULCRUM

FIGURE 25.—Lever-actuated setworks. A, Single-acting

type; twist of handle raises one pawl and lowers the

other, thus permitting advance or receding of knees

when lever is pulled. B, Double-acting type; forward

motion of lever engages upper pawls, backward motion engages lower pawls which are connected to

lever below fulcrum point so that gear turns set shaft

in the same direction as when upper pawls are engaged.

Lever-actuated devices that recede the knees

may be attached to the set shaft independently

of the advancing mechanism (fig. 25), or in

combination with it. The lever action may be

transmitted from one geared wheel on an independent shaft to a second geared wheel fixed

to the set shaft (fig. 25), or from the lever

through the recede wheel attached directly to

the set shaft. Provision is made to disengage

the pawls on either the receding or the advancing mechanism when moving the knees.

In spring-actuated receders (fig. 26), a

spring coiled about the set shaft as a core has

one end anchored to a collar fixed to the set

shaft and the other end anchored to the frame

of the setworks. It is so oriented that, as the

set shaft is turned in advancing the knees, the

spring is tightened. It is usually associated

with a double-acting setworks, since the continuous meshing of the alternate series of pawls

insures continuous tightening of the spring;

but it can also be used with single-acting setworks provided with extra pawls to hold the set

wheel on the back stroke of the lever. The

knees are receded by tripping these pawls. The

receding action is usually brake-controlled with

a lever-operated band that bears on the face of

a pulley fixed to the set shaft (fig. 26).

BRAKE

ser SHAFT

FIGURE 26.—Spring-actuated recéder.

Power-actuated receders vary in design.

Knees may be moved by means of power taken

from movable beams, chains, ropes, drums,

electric motors, or hydraulic pistons. In a common type (fig. 11, A) a beam alongside the

track is elevated with a foot-operated lever so

that it rotates a wheel fixed to a shaft having

a set of bevel gears connecting with the set

shaft. As the carriage is gigged back, the sawyer steps on the foot lever and the knees are

receded. A variant (fig. 27, ß) takes power

from a carriage truck wheel through mitered

gears to turn a shaft and friction wheel which

is lever-actuated so that it can be brought to

turn a bull wheel on the set shaft.

In the chain type of power setworks and recéder, both setting and receding are done by

meshing a sawyer-operated foot lever to a

power-driven sprocket anchored inside the

track. The sprocket engages a chain drive on

the carriage that is connected to bevel gears

that actuate the set shaft (fig. 28).
SMALL SAWMILL OPERATOR'S MANUAL 17

In rope-actuated types, the rope may be stationary or used as a continuously running belt.

The stationary system (fig. 29) consists of a

heavy manila rope extending the full track

length about 5 feet above the outside trackway

and passing over one and under another

grooved pulley of the setworks mechanism anchored on the carriage. A friction wheel attached to the shaft of one pulley engages a disk

attached to the set shaft as the rope is tightened by a sawyer-controlled lever, thus advancing

the headblocks when the carriage is advanced

or receding them when the carriage is gigged

back. A dial-and-pointer indicator registers the

set.

FIGURE 28.—Power-actuated setworks. Levers a and 6

control clutches c and d, which engage chain e for

either advance or receding. Trip / releases pawls on

setworks.

PAWL TRIP

FIGURE 27.—Power receders. A, Movable beam, frictionwheel type actuated by carriage gigback; foot lever

brings moving beam in contact with friction wheel,

which operates set shaft through gears, thus receding knees. B, Receding action obtained through geared

carriage wheel when lever brings friction wheel in

contact with bull wheel on set shaft.

FULCRUM ON

CARRIAGE

SET SHAFT

FIGURE 29.—Fixed-rope, friction-wheel type of power

setworks. Mechanism is anchored to carriage, so that

friction wheel actuates setworks when rope is

tightened against pulleys.

With the continuously running system, the

rope, powered by an electric motor, is run over

a grooved pulley at each end of the carriage

track and returned below these pulleys, and a

friction wheel is placed on the shafts of both

pulleys of the mechanism attached to the carriage. The pivoted frame is tilted so that one

friction wheel will engage the disk on either

face. The knees are advanced or receded when

one or the other friction wheel is brought

against the disk by tilting the frame with a

lever.

The carriage must be in motion in order that

the stationary system can function, whereas in

the endless-rope system setting can also be done

when the carriage is not moving.

In the drum-actuated type, a metal cylinder

approximating 8 feet in length and 6 inches in

diameter is placed just outside of, and parallel

to, the outside track at the deck end. The cylinder is constantly revolving, and can be moved
18 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

laterally by means of a lever operated by the

sawyer. Two friction wheels are fixed to the

under side of the carriage so that either may

be in contact with the revolving cylinder, the

cylinder acting as a movable bull wheel to engage one friction wheel to advance, or the other

to recede the knees. The friction wheels are

connected by belts or gears to the set shaft, and

a dial-and-pointer indicator on the carriage

records the set (fig. 30).

A drum-powered variant consists of two

drums on a shaft in the carriage frame (fig.

31). One end of the cable pulling the carriage is

fixed to each drum, so that the cable unwinds

on one and winds on the other as the drums revolve. The sawyer, by stepping on a pedal,

raises a beam alongside the trackway, thereby

releasing pawls to permit the drums to turn,

and anchoring the carriage. By manipulating

the feed lever, he causes the drums on the carriage to revolve and, through gears, turn the

set shaft until the knees advance or recede sufSAWrER'i SET LEVeH

FIGURE 30.—Drum-actuated setworks in which set lever

moves drum against one friction wheel or the other

to rotate set shaft in either direction.

\

S£T SHAFT

FIGURE 31.—Drum-actuated setworks in which drums are turned by carriage feed cable as sawyer steps on pedal

a to engage set shaft and anchor carriage by raising beam 6, which releases pawls c and engages br£|Jke shoe d.
SMALL SAWMILL OPERATOR'S MANUAL 19

ficiently. A lever type of set supplements this

power set. A selected set can be automatically

repeated and the front knee immobilized when

moving the two rear ones.

In the type of setworks and recéder actuated

by an electric motor, a 5-horsepower reversible

motor is connected by a universal joint, reducers, and gears to the set shaft. The motor

control may be placed either on the carriage or

at the sawyer's post. A dial-and-pointer indicator is used to record the headblock position,

either the dial or the pointer being synchronized to turn with the knee ; a magnetic brake is

used on the motor shaft to insure a positive

stop.

In one variant (fig. 32), the knee is automatically stopped at a preset position by means

of a wire belt running over the dial and through

small, grooved pulleys. The pulleys are arranged

on the bolster as shown in figure 32. The knee

SWITCH TRIP

SET SHAFT

FIGURE 32.—Electrically powered setworks. Electric

motor rotates set shaft, thus advancing knee, which

actuates wire belt passing over dial. Pointer is preset on dial scale for distance to advance knees, thereby also setting circuit breaker. When trip on dial

strikes circuit breaker, motor stops.

is automatically stopped at a preset position by

a circuit breaker actuated by a trip attached to

the dial. In operation, the pointer is turned to

the desired setting, thus advancing the circuit

breaker. As the motor is started, the advancing

knee turns the dial through the wire belt until

the trip on the dial opens the circuit, stopping

the motor. The diameter of the pulley backing

the pointer is such that the stop advances the

exact distance indicated in the pointer movement. The switch is fixed to the base of the

knee near the face contacting the log, and is

opened when the advancing knee brings the

lever in contact with the stop.

In one variant of the hydraulic type of setworks and recéder, a 5-horsepower electric

motor mounted on the carriage is'connected

through reducer and chain drives to the shaft

of a hydraulic pump and oil is forced through a

turbine. The device is similar in principle to

the feed works shown in figure 18. The output

shaft of the pump is connected by chain drive

to the set shaft. The oil line connects the turbine to the sawyer's position, and the direction

and magnitude of knee movement are controlled by meter valves at the sawyer's position.

In another variant (fig. 33), a hydraulic

cylinder is anchored alongside the bolster of

the center knee, its piston rod attached to the

set shaft by a roller-bearing connection. The

arrangement of pinions on the set shaft has, in

addition to the racks under the knee plate,

other racks fixed to the carriage frame to engage the under side of each pinion wheel. As

the piston thrust pushes the entire set shaft

forward, the knees are advanced a distance

equal to the piston thrust; at the same time,

the pinion on the set shaft rotates, thus also

advancing the knee, for a total knee advance of

twice the piston thrust. The sawyer controls

the advance with a second hydraulic cylinder

SET SHAFT

FIGURE 33.—Hydraulic setworks of the cylinder type.

Oil is forced into cylinder valve at port a. When

sawyer opens valve to "set" position with lever c,

oil flows through ports and tube to cylinder d, forcing piston down. Cylinder e then thrusts set shaft

forward, advancing knee, and oil is forced from

cylinder e through cylinder valve and exhaust port 6

to tank. To recede, sawyer moves lever c to recede

position of cylinder valve. Knee advance can be stopped by setting dial / for distance desired; pin on

dial actuates lever g, which closes cylinder valve.

Dial is rotated by chain drive off cylinder d. Lever h

releases clutch i to set dial.
20 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

of the sairte size as the first one, and so connected to the first by a flexible hose that the

oil expelled from the second actuates the set

piston to duplicate the thrust or withdrawal of

the control piston.

Control of the amount of thrust or knee advance is secured by turning a calibrated dial at

the sawyer's position by means of a chain and

sprockets activated by the movement of the

control piston.

A clutch between the dial and transmission

is disengaged and the dial turned backward by

hand the amount desired for knee set as indicated on the calibration. The clutch is then engaged, and the feed valve to the cylinder base

is opened by the sawyer. The thrust of the

piston turns the dial forward. A peg attached

to the face of the dial engages a lever to close

the feed valve when the dial has turned forward

the amount set.

Set accuracy is possible mechanically in the

lever-actuated type of setworks only when

gears of the rack and pinion, as well as the

pawl-tooth contact of the set wheel, are symmetrical and uniformly spaced, with no play in

them or in the bearings of the set shaft. Machine-cut rack-and-pinion gears and set-wheel

teeth make for better symmetry and uniformity of spacing than do cast-iron ones. Several

staggered pawls insure freedom from play

better than does a single one.

_ Pegs, notches for a spring-controlled trigger,

dial-controlled pawl trips, and similar devices

save time and promote accuracy. A mechanism

by which the stop shoe can be raised over the

intervening pegs where a longer stroke is desired (fig. 34) is preferable to the single-peg

type (fig. 26, A). There is very little difference

in forward-operating speed of the various types

—a single full throw of the lever advances the

SET- SHAFT

FIGURE 34.—Mechanism for lifting stop shoe over peg

of single-acting setworks without tripping the pawls.

FIGURE 35.—Types of indicators showing the number

of boards of a given thickness that can be taken. A,

Cylinder type; B, board type.

knees from 2 to 21/2 inches. A double stroke

(forward and back) of the double-acting type

can be set to give the same knee advance as a

single stroke of the single-acting type. This

setting obtains greater leverage and is often

used with heavy logs.

Precision setting is possible with four of the

power mechanisms described, the electric using

either the switch-breaking automatic stop or

the control at the sawyer's position, and the

hydraulic with either metered valves or control

piston and automatic valve shutoif. In other

power types, the operator stops the advancing
SMALL SAWMILL OPERATOR'S MANUAL 21

knee when the pointer on the scale indicates it

has moved far enough. Perfect coordination is

not possible and, though they save labor, such

mechanisms are partly responsible for inaccurate sizing of the lumber cut.

The lever type of recéder does not have the

possibilities for fast production, particularly in

sawyer-operated setworks, provided by the

spring and power types. The type that is independent of the advancing mechanism requires

an extra lever and has no particular merit over

the combined type. Spring and power types act

to recede the knees quickly. The spring type

can function when 1>he carriage is stationary as

well as moving, but requires somewhat greater

leverage to advance the knees. The beampowered type is quickly operated by the sawyer

while the carriage is gigging back. The chain

type of power recéder, while it can be footoperated, requires extra pulleys, belts, chains,

shafts, and gears. The stationary-rope type recedes only when the carriage is in motion. With

moving-rope, electric, and hydraulic types, receding is independent of carriage movement.

All types of setworks have indicators to show

the distance between the face of the knee and

the saw line. Some, in addition, indicate the

FIGURE 36.—Indicator directly on bolster and knees,

where readings are difficult.

number of boards of a given thickness that can

be taken by sawing through and through (fig.

35, A, B). The type having numbers and pointer

on the bolster and knees (fig. 36) is least satisfactory because of poor visibility and the difficulty of quickly centering the pointer on the

desired mark. A vertical gage board in sawyeroperated setworks, or a wheel gage where the

sawyer rides the carriage, is easier to read and

can guide the sawyer after the final turning to

utilize the cant.fully.

DOGS

Dogs used on small mills employ either a

spike or a hook to grip the log, but in mechanical details they vary widely. The basic types

are (1) those using a fixed post with the spike

attached or revolving about it; (2) those with

a sliding post ; (3) the hammer dog with spike

arm and hammer moving through a fixed arc;

and (4) the "boss" dog with lever-actuated

hooks thrusting out from the knees.

Included in the fixed-post, manually operated

types are those shown in figure 37. The rack

variation (fig. 37, A) consists of the spike and

pinion wheel fixed to the dog housing and the

rack machined or stamped into the fixed post.

Pawls engaging the rack help keep the spike

embedded as the pinion is turned when the

lever is pulled down. The variation shown in

figure 37, B employs an eccentric to hold the

housing to the post. In one variant of the

threader post or screw dog (fig. 37, C), the

hooks are appended to a housing threaded to

the post ; pawls hold the housing in place or can

be withdrawn to permit rapid lifting or lowering of housing. By turning the fixed post, the

dog is raised or lowered as desired. The type of

dog shown in figure 37, D, consists of a spike

at each end of a lever arm that can be rotated

around the post. Arms are usually of unequal

length, this dog being used mainly to provide

additional dogging for large logs. The weight

of the dog is relied on to clinch the log properly.

Fixed-post, power-operated dogs are actuated

by air or hydraulic cylinders and electric

motors. The air or hydraulic dog (fig. 37, E)

consists of the cylinder fixed to the dog housing

and the piston rod anchored at the base. A bottom dog at the end of the piston rod has enough

play to function. The fixed post slides laterally

in guides attached to the knee and propelled by

the piston of a second cylinder. A small electric

motor fixed to the carriage frame runs the

pump for hydraulic pressure. The shell of the

hydraulic cylinder is fixed to the dog housing,

and the end of the piston rod is anchored to

the base of the knee. Cylinders for the airdriven dog are installed in the same way. The

electric dogs have a chain attached to the top

and bottom of the housing and thence over

sprockets at the top and base of the fixed post

and back to the sprocket propelled by the

motor (fig. 37, F). Provision to break the current at a definite load prevents excessive strains

on the assembly.

Moving-post types of dogs are shown in

figure 38. A down pull on the lever gives a

downward movement of the spike, and in those
22 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

FiGURK 37.—Fixed-post types of manually operated

dogs. A, Rack-post; B, eccentric-lock; C, threadedpost; D, rotating-spike; E, air or hydraulic; F,

electric.
SMALL SAWMILL OPERATOR'S MANUAL 23

FIGURE 38.—Moving-post types of manually operated dogs. A, Single-bar single dog, lever at base; B, single-bar

single dog, lever at midpoint; C, single-bar top and bottom dog; D, double-bar top and bottom dog; E, yoked,

bar, dog with pivoted top and rotating bottom dog; F, double-bar threaded-post dog.
24 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

illustrated in figure 38, C, D, and E, a simultaneous upward movement of the bottom dog.

In another variant of the screw dog (fig. 38, F)

the sliding bar movement results from threading it to the fixed screw shaft. The sliding

double bar that houses the spikes of the variant

shown in figure 38, E moves up or down about

4 inches. The spikes are placed about 3 inches

apart and fulcrum on a pin. A second pin under

the rear of each spike provides a backstop when

the spike engages the log, whereas those below

are free to pivot down and out of the way.

The hammer dog (fig. 39) is at the end of a

radial arm, the opposite end being fixed to the

knee. The hammer and lever are also pivoted

at the same point, the hammer following the

arc of the spike as the lever is raised. This dog

is intended to provide additional dogging on

large logs when making the first cuts.

The "boss" dog (fig. 40) consists of a series

of levers and fulcrums that synchronize the upward and outward thrust of one set of hooks

with the downward and outward thrust of another set as the lever is pulled down.

Dogs should immobilize the log or cant tight

against the upright faces of the knees and

should operate quickly. The cant is pulled toward the uprights by putting the bevel wholly

on the back of the dog bit (fig. 37, D) or in

combination with a lever- or power-actuated

pull (fig. 38, ^). The types shown in figures 37,

D, and 39 are used to hold the log better when

sawing the first face. The pull toward the upright is least effective in types dependent upon

jamming the bit by hand (fig. 37, A, B, and D),

and more effective in types supplementing the

FIGURE 39.^Hammer dog.

FIGURE 40.—"Boss" dog.

hand drive with a lever or screw pull as shown

in figures 37, C and 38, A-F, or with a hammer (fig. 39), or with power drives (fig. 37, E

and F).

Rated on the time required to operate them

manually, the types shown in figures 37, A, B,

and D ; 38, £ ; 39, and 40, require only a simple

drive or lever pull ; those in figures 37, C and 38,

A, B, C, D, and F require unclamping, driving,

clamping, and a lever pull or screw turn.

Types shown in figures 37, C and 38, F are

usually restricted to carriages fitted with log

beams; and types shown in figures 38, A, B, C,

D, and E, 39 and 40 are Hmited to mills where

the setter rides the carriage. Power-actuated

dogs (fig. 37, E and F) bring instantaneous and

adequate action to insure tight gripping of

cants, and can be set up to be operated either

from the sawyer's position or by a man on the

carriage.

The foregoing discussion leads to these conclusions: Mills without a setter on the carriage

cannot depend upon the manually operated

types of dog shown in figure 37, B to pull the

log against the upright, whereas the dogs

shown in figure 37, A and C, tend to do so, and

each requires few motions. With a setter on the

carriage, the types shown in figure 38, ^ to D

and F tend to hold the cant against the knees,
SMALL SAWMILL OPERATOR'S MANUAL 25

but involve several motions; the type shown in

figure 40 does this with fewer motions needed,

but may score the face where the claws grip,

whereas that shown in figure 38, E does not.

Types shown in figures 37, C and 88, F hold

cants against the knees, but usually a hammer

or drop dog is added the better to hold the

round log. The power dogs (fig. 37, E and F)

hold the cant against the knees and also lend

themselves to the sawyer's control.

EDGERS

Three types of edgers are used by small mills.

The single-saw type (fig. 41) usually employs a

light flatcar pushed along a trackway to carry

the board through the saw one edge at a time.

In the type having two or more saws on a single

mandrel (fig. 42) the boards are fed through

the saws by power rolls and one or both sides

are edged or ripped for grade and size requirements. The vertical-edger type (fig. 43) with

two or more saws on a vertical mandrel is installed ahead of the headsaw to edge the boards

as the carriage carries the log through the saw.

The single-saw carriage edger carries a saw

14 to 16 inches in diameter running at approximately 2,000 revolutions per minute on a mandrel about 1 I/o inches in diameter. The carriage

is a platform about 14 feet long and 2 feet wide

mounted on trucks, the flanged wheels of which

run over a flat-topped track.

In the multiple-saw type, all saws may be

movable along the mandrel, or one may be fixed

and the others movable. If a fixed saw is used,

it is usually attached to the mandrel about 6

inches from one edge of the feed bed, depending on whether it is a left-hand or right-hand

edger. A left-hand edger is used on a right-

«C^*Í'S1íIA&^^-^ ¿ ..;:.j;»sik¿. .,fAÍJK¿a t¿-JÍM.¿A4

FIGURE 41.—Single-saw type of edger.

M-a2217-F

FIGURE 42.—Multiple-saw type of edger with powered

roll feed.

hand mill and a right-hand edger on a left-hand

mill. Viewed from the front, a log passes to the

right of the headsaw in a right-hand mill, to

the left of the headsaw in a left-hand mill. A

movable guide on the feed bed can be placed so

that either no edging is done on this saw or the

full 6-inch width is taken; with adjustable

guides, any width between zero and 6 inches

can be taken.

The movable saws slide along two keys fixed

to opposite sides of the mandrel, each saw being

connected, by means of a fork engaging opposite sides of the collar or guides on the saw,

to a lever arm extending to the front of the

machine and fulcruming at about its midpoint.

The saws are normally 14 to 16 inches in diameter and are held with a 5- or 6-inch collar.

An indicator fixed to the lever arm just ahead

of either the saws or the feed table guides the

operator in spacing the saws as it moves over

a scale fixed to the machine ; notches or holes in

the frame, together with pawls or pegs on the

lever arm, hold the saw in the position required.

The board is held in place and fed through

the saws by means of a top and bottom feed

roll, one pair being just ahead and another behind the saws. The bottom (feed) rolls are
26 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

fluted or scored and power driven. Both top

(pressure) rolls are smooth, turn by contact

with the moving board, and are in a swing

frame to allow them to move up or down for

different thicknesses of stock. The front pressure roll is of small diameter (about 2Vä

inches) to obstruct the operator's view of the

saws as little as possible ; the rear one is usually

larger, 3 to 6 inches in diameter. These pressure rolls swing away from the operator when

being elevated.

The feed rolls are usually belt-driven, power

ordinarily being taken off the edger mandrel at

the end opposite that to which the drive pulley

is attached. They are adjusted to feed at about

100 to 125 feet per minute. The feed bed also

has three dead rolls, one in the center and one

at each end lined up with the powered feed

rolls ; in one type, a chain with lugs helps propel

the board to the power rolls. The rear bed may

have dead rolls and a board guide lined with the

fixed saw ; or it may be a plane surface.

Vertical edgers are mounted on a specially

built metal husk frame in such a way that the

perimeter of each horizontally mounted saw

exactly reaches the log side of the headsaw cutting plane at a line about 2 feet ahead of the

headsaw. Thus, as the carriage is gigged back

to the deck, the cant set out for the next headsaw cut, and the carriage advanced, the edger

saws edge to the thickness set. The bottom saw

may be fixed to the vertical shaft, or all saws

may be movable up and down the shaft by

means of levers or hydraulic pistons manipulated by the tail sawyer to edge or rip to required sizes.

Saws are of the inserted-point type, usually

about 26 inches in diameter and with collars

9 inches in diameter. They are movable up or

down along two keys fixed to opposite faces of

the shaft, and rotate in a direction opposite to

that of carriage feed. Vertical edgers, rarely

used outside the Douglas-fir region, are found

on mills with double circular headsaws operating on logs of large diameters (fig. 43).

M-B2128-F

FIGURE 43.—Vertical type of edger installed in front of

headsaw.

TRIM AND CUT-OFF SAWS

Four types of trim saws used on small mills

are: (1) The single cut-off, (2) the "Canadian"

trim saw, (3) the two- or three-saw cut-off, and

(4) the battery trimmer.

The single cut-off saw (fig. 44) consists of a

swinging frame pivoted to bring the saw across

the flow line of the material. The frame normally rests so that the saw is within a guard clear

of the flow line. Trimming is done by pulling

the saw across the material. The pivot can be

above or below the flow line. If its function is

mainly to make boiler-room fuel, it may be located opposite the tail sawyer-edgerman, who

pulls slabs across the edger feed table and

segments them with or without assistance. If

its function is mainly to cut up slabs for fuel

wood or to trim ties and timber, it is usually

located near the back end of the edger in the

rolls from the headsaw. If the main function is

to trim boards, it is usually near the back end
SMALL SAWMILL OPERATOR'S MANUAL 27

of the edger across from these rolls. The larger

sizes take a saw up to 42 inches in diameter, but

saw diameters normally are 24 to 30 inches.

The Canadian trimmer is used where mills

and concentration yards are equipped with conveyor chains that carry the material past two

fixed saws spaced about 13 feet apart along the

conveyor chain and 16 feet, 1 inch, or other

standard lengths, across the chain. The first

saw on the line squares up one end, or the board

is so placed as to trim a defective end. An operator at the opposite side of the conveyor table

then places the board for accurate trim to

=B=a

Ci

..I

ah&

EHIW

^-ito

l|>Hj^HnH=HiHri}ei

=^

FIGURE 44.—Single cut-off trim saw.

M-a2215-F

FIGURE 45.—"Canadian" trim saw.

length by the second saw, being guided by

markers on the table (fig. 45).

The standard two-saw trimmer (fig. 46) consists of two (or, rarely, three) saws on a single

mandrel. The saws are movable along the mandrel, their spacing being controlled with a crank

or wheel to permit trimming a variety of

lengths. In hand-feed trimmers the material is

placed in front of a movable straight-edge guide

and pushed through the trim saws. In the

power-feed type, moving chains with lugs carry

the boards through the trim saws. In some

models the saw-spacing crank or wheel is attached to a movable transfer block ; in others it

is fixed to the frame. The thickness of the stock

trimmed depends upon the saw diameter; 16-

inch saws take 3 inches, 20-inch saws 5 inches.

Saws run at a rim speed of 9,400 feet per minute, and the feed rate is gaged at 30 or 50 feet

per minute.
28 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

FIGURE 46.—Two-saw trim saw.

M-S2t93-F

FIGURE 47.—Battery trimmer.
^MALL SAWMILL OPERATOR'S MANUAL 29

The battery trimmer (fig. 47) is the smallmill adaptation of the multiple-saw trimmer

used on larger mills. Four or more saws, each

on a separate mandrel and each in a pivoted

frame comparable to that of the single cut-off

saw, are placed in line across the line of flow of

the material. The operator, through lever action, can extend a selected saw to cut a given

length, the remaining saws being retracted

either above or below the line of flow of the

material.

Automatic slab cut-oflf saws (fig. 48) are in

use. Provision is sometimes made to advance

the slab when the saw is clear of the trough,

and to stop its advance when the saw is passing

across the trough, but equipment is often used

without such controls. Usually the cut pieces

drop onto a conveyor and are carried to a hopper or heap outside the mill.

A half-pinion g (fig. 48) fixed to the drive

shaft engages the pinion, activating the slab

belt for half a revolution. The pulley n, which

E DETA/L

ALTERNATE TO HALF PINION DRIVE

, mm

FIGURE 48.—Automatic slab cut-off saw. Saw a, is propelled as cam h strikes pitman rod c, striking slab held under

idler rollers d. As saw completes cut, half-pinion gear g engages conveyor mechanism to advance slab for next

cut through pulley n. Plunger e, actuated by cam /, is used to realine teeth of half-pinion g if they fail to mesh

properly with conveyor gear mechanism. Plate h supports short slabs and backstrip i controls length of cut piece.

Guide rolls j hold shaft c in line. End roll k rotates as cam 6 strikes it. Cam I serves as counterweight to cam 6.

Shaft m coordinates conveyor belt with cams by belt. The alternate drive shown functions off shaft m through

a rod that rotates conveyor pulley w. , . ,

471449°—58 3 . \ '
30 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

activates the slab belt, should have a circumference of twice the desired length of the cut

piece. In order to insure that the half-pinion g

meshes with the companion pinion wheel, the

cam-plunger mechanism shown in the detail is

used. The point of the plunger is conical, and

the plunger entering the space between two

cogs should be appreciably smaller than the

opening. One-half of cam / is thicker than the

other one-half of the circumference, the increased thickness being equal to the thrust required to bring the plunger between the cogs,

and need not exceed one-half inch. This cam is

attached to the drive shaft so that its raised

face rotates under the plunger pin when the

half-pinion is disengaged from its companion

pinion, being adjusted to lock the pinion as the

half-pinion clears. A strong spring is required

on the plunger.

An alternate method for driving the slab belt

is shown in figure 48. Sprockets and chain drive

from shaft m transmit power through beveled

gears to turn the wheel to which the plunger

bar is eccentrically attached so that it turns

the cogged wheel attached to the drive pulley of

the slab belt. The length of slab cut can be

varied by varying the distance from the center

at which the plunger is attached to the wheel.

The idlers d are segmented. Plate h provides

support for the slab near the saw, and the backstrip i fosters uniformity in cut lengths.

The cam b activating the pitman rod c has its

greatest length along a radius equal to about

two-thirds the thrust required to bring the saw

across the trough ; a 15-inch distance along the

radius pushes the saw approximately 20 inches

when the hook-up is proportional to that shown

in figure 48. A paper outline of this cam can be

made by drawing a circle with a 4-inch radius.

Using the 4-inch original radius plus the required interval for saw thrust as a new radius,

circumscribe a concentric circle around the one

with the 4-inch radius. Divide one-half the circumference of this large circle into about eight

equal parts and draw radii from the center to

each point. The 4-inch radius, plus its projection for saw thrust, gives the starting point in

drawing the outline of curvature of the cam.

The other points are 7/8, 6/8, 5/8, 4/8, 3/8,

2/8, and 1/8 of this projection as measured

from the circumference of the smaller circle

outward along the radii drawn to the circumference of the larger circle, starting with that

radius nearest to the starting point. Using the

paper outline as a pattern, the cam can be sawed

from 2-inch plank. It is advisable to make two,

using one to counterbalance the other as indicated by the dotted outline (fig. 48).

The pitman rod has a roller, k, attached to

the part contacting the cam, and moves in

guide ;. The pitman rod has a length such that,

when fully retracted as in figure 48, the saw is

held slightly beyond dead center, the thrust of

the saw frame serving to hold the pitman rod

against the cam. The saw frame should be

partially counterbalanced to lessen the shock as

the pitman rod drops along the straight face of

the cam.

LOG TURNERS

Small mills operating in small timber find log

turners of little practical value. An experienced

deckman with a short-handled cant hook can

turn logs under 20 inches in diameter as quickly

as can power turners, and with less shock to

the carriage. They are rarely used in really

portable mills, but are practical in semi-permanent sets cutting large logs. The slip-block

mechanism is useful in medium and large logs

because it lessens the shocks to equipment and

the physical work of placing the log. It turns

the log toward the deck. The overhead type is

practical where large logs must be handled, being durable and faster than cant hooks. The

friction and rocker-arm types must be kept in

accurate adjustment and be backed up by heavy

carriages and trackways ; they require a pit or

elevated mill and a sturdy carriage.

Types of log turners used on small mills include (1) the slip-block or the hinged-block ;

(2) the overhead; (3) the friction; and (4) the

rocker-arm type. FIGURE 49.—Slip-block log turner.
SMALL SAWMILL OPERATOR'S MANUAL 31

The slip-block type consists of a shaft having

a metal or wood arc approximating a half circle

fixed to each end. The shaft is seated in two

deck skids in such a way that the flat face of

the turner is slightly below the skid top when

not in use, and the perimeter of the arc reaches

within an inch or so of the skid end when used.

It is operated by means of a foot lever directly

attached to the arc nearest the sawyer (fig.

49), the arcs being elevated and the log turned

down against them. As the arcs turn back to

their original position, the log slides back toward the knees. The hinged-block type consists

of a single or double roll housed in a hinged

frame that is bolted to the side of the skid to

allow the rolls to be above the skid when in

use and below the top of the skid at other times

(fig. 50).

FIGURE 50.—Hinged-block log turner.

M-82216-F

FIGURE 52.—Double-bar friction log turner.

SHIFT DIRECTION

FIGURE 51.—Overhead log turner.

FIGURE 53.—Single-bar friction log turner. L-shaped

bar is raised at lower pulley by chain that winds on

drum shaft when friction wheel is brought against

drum wheel by lever. Guides (not shown) hold bar

upright as it is raised through log deck. Chain is

anchored at top end to deck beam.
32 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

In the overhead type of turner, two conetype friction wheels are lever-actuated to slide

along the key of a belt-driven shaft. At opposite

positions one is brought in contact with a bevelfaced, driven friction wheel fixed to a shaft,

thus winding or unwinding a chain having one

end fixed to the shaft and a hook on the other

end (fig. 51) for attachment to the perimeter of

the log. A double-geared variant designed to

give slower and more powerful turning has a

wheel fixed to the second shaft and geared to a

wheel fixed to a third, the latter carrying the

chain and hook. These turners are mounted so

that the winding shaft is parallel with the

trackway and over the carriage at the deck.

In the friction type of log turner, two spiked

lever arms fulcrum on cams so shaped as to impart an upward thrust and a backward withdrawal to the arms with each revolution ; these

cams are so adjusted that the upward thrust of

one synchronizes with the withdrawal of the

other (fig. 52). They are brought from the inoperative position below the deck skids to the

operative (upright) position by friction of the

wooden kicker-bar extension frame clamped to

the cam shaft ; by reversing the shaft they are

rotated to the inoperative position. Forward or

reverse drive of the cam shaft is accomplished

by the friction-wheel mechanism used with the

overhead type (fig. 51).

Another design of friction turner (fig. 53)

has a single bar that is pulled upward between

guides by a chain that winds around the drum

shaft when the power-driven, lever-actuated

friction wheel is brought in contact with the

drum wheel. Upon release of this contact, the

bar drops down. Hinged teeth on the bar engage the log as the bar is forced upward and

drop back as the bar drops.

On a variant of the single-bar design, the base

of the bar pivots on a bolt attached to a lever

arm, one end of which pivots in turn on a bolt

anchored to the foundations. The bar is moved

up and down by a cable that is attached to the

bar and passes under a pulley on the lever arm,

as shown in figure 54. The other end of the

cable is attached to the core of a shaft implemented by drum and friction wheels.

In the rocker-arm type of turner (fig. 55), a

shaft with two or more arms under the deck

skids pushes logs onto the carriage, and a

similar shaft on the carriage throws the logs

back on deck with a turn-down effect. The

deck and carriage rocker arms are turned with

a hydraulic piston attached to a lever arm from

the shaft (fig. 55).

CABLE TO DRUM OPERATED THROUGH

FRICTION WHEELS

DOGS PIVOTED TO SWING

BACK INTO POST ON

DOWNTHRUST

ROLLER GUIDE

' ->'.

wv/w

FIGURE 54.—Variant of single-bar friction log turner.
SMALL SAWMILL OPERATOR'S MANUAL 33

FIGURE 55.—Rocker-arm log turner.

METAL DETECTORS

Military mine detectors (fig. 56) developed

by the Army have been successfully used by

mill operators to locate metal concealed in logs.

The most sensitive type released as surplus by

the Army, series SCR-625, requires about the

same operating skills and precautions against

rough usage as does a portable radio. The instrument is sensitive to metals normally embedded in logs, and the time required to examine a log is comparable to that needed to scan

it with a spotlight field a foot in diameter. Usually, only logs suspected of harboring metal

are examined. Nonportable instruments are

available in which the log is passed through a

ring, but such equipment is not ordinarily used

by small mills.

M-B33

FIGURE 56.—Mine detector used for locating

metal in logs.
34 HANDBOOK 27, U. S. DEPARTMENT OF AGRIGULTURE

CONVEYOR SYSTEMS

Conveyor systems find use at small sawmills

both to carry lumber from the headsaw and to

remove sawdust, chips, and slabs. Practically

all small mills have chains or a blower to carrj^

the sawdust from the saw pit. Those with a

capacity of up to 1,000 board feet per hour

usually have a line of dead rolls from the saw

to the back of the mill, and perhaps a car, to

remove slabs or lumber. With greater production and in semipermanent sets, live-roll, belt,

and chain conveyors are used.

Sawdust Chains

To operate sawdust chains, power is taken

from the mandrel through a pulley-belt or

sprocket-chain device that drives a shaft and

set of gears. These may turn the sprocket that

drives the sawdust chain, or may turn an intermediate sprocket connected to the one on the

chain. The outer end of the chain passes over

an idler sprocket or pulley anchored at the apex

of the pile. The chain (fig. 57) usually has lugs

and commonly has a working strain rating of

about 300 pounds, but chains up to 1,000 pounds

in capacity are available. The return chain goes

B

FIGURE 57.—A, Links and B, lug of sawdust chain.

directly to the sprocket under the saw when

driven from under the husk; when driven over

the mandrel, it is kept high enough to clear the

carriage.

Faulty functioning of sawdust chains is a

common cause of delay in small-mill operations.

The chain commonly used (a cast-iron, detachable type) is low in strain resistance. To lessen

the chance of breakage under normal loads, the

following limits of conveyor distances are suggested for various standard link sizes : Size No.

45, 40 feet; No. 55, 60 feet; No. 57, 80 feet; No.

67, 150 feet; No..75, 200 feet.

Chains driven by a chain-and-sprocket transmission from the mandrel are more subject to

breakage under abnormal loads than those

driven by a belt transmission, but belts in the

saw pit may be flooded in unsheltered mills. For

such mills a short belt drive from the mandrel

to a pulley anchored at the base of or above the

husk, and a chain drive from this pulley shaft

to the sprocket and gears in the saw pit can be

used, both outward and return lines of the sawdust chain being under the trackway. In a variant the sprocket driving the chain is anchored

about 8 feet above the husk and a pulley is anchored in the pit, the outgoing chain thus being

under the trackway and the return chain overhead to clear the carriage. A belt from the mandrel through reducing transmission drives the

sprocket.

Sawdust Blowers

Sawdust blowers are generally belt-driven

from the mandrel and may be located at any

convenient position near the saw (fig. 58). A

left-hand blower is used on a right-hand mill,

and vice versa. Fans have a diameter of about

24 inches, and to move the sawdust eifectively

they are run at speeds up to 3,500 revolutions

per minute. The intake may be installed between the saw and the blower, so that the sawdust passes through the fan; but with the intake in the discharge pipe beyond the blower,

damage to fan blades is avoided. A coarse

screen or grate is usually placed over the hopper intake to screen out the larger chips.

Lower initial costs, together with greater

convenience in moving, make sawdust chains

the choice in most portable mills cutting up to

100,000 board feet at a set. Blowers are suitable

in mills cutting several hundred thousand feet

at a set, as the sawdust can be propelled 100

feet or more and deflected over a considerable

arc. Blowers can be set up to service both the

headsaw and edger.
SMALL SAWMILL OPERATOR'S MANUAL 35

FIGURE 58.—Sawdust blower.

Dead Rolls

In mills without edgers, a single dead roll

(fig. 59) on a stand bringing the top of the roll

to the level of the carriage bolsters is sometimes used behind the saw to hold material off

the ground. The roll is made of wood or iron,

is about 6 inches in diameter by 15 inches long,

and has a shaft turning on bearings in the

stand. Most small mills, however, have a series

of dead rolls extending from the saw to the rear

FIGURE 59.—Single dead roll used to support material

. when mill has no edger. . ' . . •

M-B221B-F

FIGURE 60.—Series of dead rolls, used by mills with or

without edgers.

of the edger or rear of the mill (fig. 60). Some

are inclined, so that gravity aids the man pushing slabs, timbers, and other material over

them. The size most commonly used by board

mills comes in 10-foot sections, each having

seven rolls spaced about 18 inches on centers;

each roll is 2 inches in diameter and 15 inches

long, and is supported on an angle-iron frame

by ball bearings. Heavier rolls are available for

tie or timber mills.

Live Rolls

Live (powered) rolls (fig. 61) manufactured

for small-mill use are from 6 to 12 inches in diameter and 18 to 30 inches in length; they are

made of cast-iron or steel. They are spaced

about 4 feet apart in a frame that brings the

top of each roll about 30 inches above the floor,

and are rotated at about 300 lineal feet per

minute by either beveled friction or cut gears

on a shaft usually placed on the edger side of

the rolls. This shaft is geared to give forward

or reverse drive.

Home-made live rolls can be improvised from

dead rolls by connecting them with a narrow

belt, usually driven from the saw arbor. Speed

reduction from mandrel to rolls is secured by

connecting the arbor to a pulley approximately

a foot in diameter with a 2-inch belt which is

given a half twist, and connecting the shaft of

this driven pulley, anchored about 3 feet behind

the husk and below the rolls, to the first roll

with a sprocket-and-chain drive. This chain

drive is usually at the edger side of the roll.

Rolls approximate 9 inches in diameter and 2

feet in length, being spaced about 44 inches.

Midway between adjoining rolls a belt tightener

of about 4-inch diameter is placed below the

level of the top of the roll. A 2-inch belt is then

threaded over each roller, usually at the end

farthest from the edger, and under the tightener, thus providing a set of powered rolls.

Routing requirements vary with the particular mill set-up. All material up to 2 inches in
36 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

FIGURE 61.—Live (powered) rolls.

thickness may be routed through the edger;

the slabs and timbers pass down Hve rolls to

dead rolls at the rear of the mill. A cut-off saw

is often installed in the dead-roll line to trim

timbers and cut up slabs and edgings. Sometimes the live rolls extend to a refuse conveyor

that takes slabs and edgings to the burner;

timbers are shunted to dead rolls leading to the

dock. Boards generally pass through the edger

and a single trimmer saw, or drop onto conveyor

chains and pass through a Canadian or gang

trimmer to the sorting line.

Belt Conveyors

Belt conveyors are used on some small board

mills to carry slabs and boards from behind the

headsaw. Idler rolls spaced at 6-foot intervals

support the belt (usually of fabric and about

15 inches wide) which runs over a driven pulley

at the rear of the mill and an idler pulley behind

the headsaw. Slabs continue to the refuse chain

and burner. Boards are pulled off by the edgerman and fed through the edger. Edgings go

back onto the belt and to the burner.
SMALL SAWMILL OPERATOR'S MANUAL 37

Chain Conveyors

Some semipermanent small mills elevated off

the ground and producing 2,000 board feet or

more per hour are equipped with a conveyorchain refuse system. The routing varies among

mills. A simple routing takes sawdust from the

headsaw and edger via chutes under the saws

feeding onto the conveyor-chain trough below

the floor. The tail edger throws the edgings into

the trough through an opening in the floor between the line of rolls and the edger. About 20

feet of live rolls bring slabs onto dead rolls,

where they are shunted through the hole or

sawed for fuel with a swing saw in the line of

rolls. The refuse from the trimmer is ordinarily

shoveled into the hole at odd intervals. The

chain carries the refuse to a burner.

Conveyor chains are used for lumber where

production is 2,000 board feet or more per hour,

mainly of boards and involving considerable

sorting ; or to expedite dipping. The chains provide a continuous line beyond the trim saws for

the distance required by dip tanks, grading,

and separations; for example, 14 feet for dipping, 10 feet for grading, and 6 feet per separation, which for a set-up with 10 separate units

makes an over-all length of 84 feet. The table

is about 30 inches above floor level. The usual

arrangement for material up to 16 feet in

length is one chain in the center and one located 5 feet 8 inches to either side of the center-line. The detachable-link chains (fig. 57)

without lugs travel at a rate of about 25 feet

per minute in guides. If a dip tank is in the line,

the sprocket drive is on the entering side, and

the section of chain for the tanks is separate

from the sorter-table section. The drive for the

latter preferably should be at the end farthest

from the edger, but can be at the mill end. Ten

horsepower will drive the loaded chain.

Trash-Disposal Systems and Methods

Mills cutting less than 150,000 board feet at

a set often make no provision for trash disposal

other than the chain or blower for sawdust

and one or two men who carry slabs and edgings to a pile just clear of the mill or to a nearby fire. Seventy feet is about the limit ; carrying

slabs farther is a man-killing job. Burning close

to the mill, on the other hand, is hazardous,

and adds to the discomfort when smoke blows

to the mill.

On some mills of this type the drudgery is

lightened by the use of cars on which the slabs

and edgings are loaded as they are cut. The

loaded car is pushed to a dump or fire pit. If

slabs can be sold, this type of mill may have a

swing cut-off saw in the line of rolls beyond the

rear of the edger. The operator cuts the slabs

and edgings to the required lengths, and ricks

them on a wagon with a platform bed or on a

buggy. Usually the lumber is piled on other

wagons or buggies just behind the mill and

hauled to yard piles.

In more permanent types of mills, the belt

conveyor emptying into a chain conveyor

trough, or the under-floor chain trough system

already described, effects waste disposal. Where

slabs have a sale value, an automatic cut-off

saw is installed and the cut stock is transported

to the load-out station on a conveyor chain.

Burners for slabs and edgings ordinarily do

not require forced draft, but it is necessary if

sawdust is burned. A simple type of burner

(fig. 62, A) suited to portable mills, called a pit

burner, can be built by setting eight poles about

8 inches in diameter and 16 feet long firmly in

the ground at equidistant points in a circle. The

diameter of this circle is as little as 24 feet in

some installations, but 36 feet is suggested.

The ends of two 36-foot lines at right angles to

each other, and intersecting at the center of

the proposed "pit," give the location of four of

the poles. Two 14-foot boards, if one end of

each is centered on adjacent poles, will meet at

points where the intervening four poles are required. For each of the eight sides, six 1- by

6-inch by 14-foot boards are nailed horizontally

to adjacent poles, beginning at the ground line

and spaced 2 feet apart, on the pit side of the

poles. Strips of corrugated metal roofing are

then nailed to the pit side of these boards to

enclose the pit.

The refuse conveyor enters the burner at

about the 10-foot level. If a blower is installed,

the pipe enters the burner just below ground

level, with the outlet directly below the end of

the spillway. Old grates, bars, or even rough

boulders can be put in the outlet to keep it open

and diffuse the draft. The burner should be at

least 75 feet from the mill, and located so that

prevailing winds do not blow the smoke into the

mill. A 1 i/2-horsepower motor will run the fan.

A barrel of water and a bucket are usually kept

conveniently at hand in case the burner catches

fire.

The two types of refuse burners shown in

figure 62, B and C, have received the approval

of the California State Division of Forestry because their design and construction minimize

the fire hazard. More costly than the simple pit

type of burner, they are perhaps best suited for

use at permanent sets where their higher cost

can be amortized over a long period.

The refuse burner shown in figure 62, B, requires the following materials: Eight pieces of

80-pound rail, each 40 feet long ; eight pieces of

20-pound rail, each 12 feet long; one,circular
38 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

FIGURE 62.—Three types of refuse burners. A, Pit type for portable mills; B, enclosed refuse burner; C, enclosed

sawdust burner. Types B and C approved by California State Division of Forestry on basis of safety.
SMALL SAWMILL OPERATOR'S MANUAL 39

iron top piece; 800 feet of li^-inch pipe for

bands ; 4,000 square feet of 18-gage flat metal ;

1,200 square feet of No. 3 mesh steel screen;

three steam grates; a li/2-horsepower motor

with blower and pipe. The construction is such

that each rail strut consists of a 20-pound rail

welded to the top of the 80-pound rail. The circular iron top piece, together with the pipe

rings, conñnes the rail struts.

The sawdust burner shown in figure 62, C,

consists of the following materials: 2,000 fire

brick; 4 bags of fire-clay mortar; 600 square

feet of 3/8-inch iron boiler plate; a stack with

wire-mesh vents (5 wires to the inch) and a

metal cap; a li/2-horsepower motor with blower

and 20 feet of galvanized 4-inch drain pipe. The

burner stands on a concrete base 73 square

feet in area. It has one clean-out door 2 feet

square and three side doors each 14 by 16

inches in size. The pipe conveying sawdust has

a swinging door fitted in it.

Burning of existing sawdust piles, especially

wet ones, may be speeded up through the use

of a small blower powered by any convenient

unit of 5 horsepower or more. A pipe at least

25 feet long should be attached to the blower

to get it away from any source of fire. A steady,

diffused flow of air is effective, whereas a direct

and intense draft at the zone of burning is not ;

hence, outlet pipes should be 8 inches in diameter or larger, the fan should be run at slow

speeds, and the air stream should be directed

to the ground at the base of the pile on the

windward side. The blower must be moved as

wind direction changes and as the sawdust pile

is consumed at the point of attack. Anchoring

the blower to skids provides a firm base, yet

gives ready mobility.

POWER AND TRANSMISSION EQUIPMENT

Small mills expend from 50 to 95 percent of

their available power on the headsaw. The

amount of additional power used varies with

the equipment of the individual mills, such as

edgers, trimmers, cut-off saws, powered mechanical deck and carriage accessories, and

transfer and conveyor systems, requiring a

fairly constant amount of power regardless of

operating rates. The power used at the headsaw and carriage, on the other hand, varies

greatly between full loads and lesser ones.

The headsaw load is influenced chiefly by

width of cutting face, thickness of chip (feed

rate), and wood density. Even where power is

not limited, it is possible to build up loads beyond the capacity of the saw to cut properly

by combining a wide cutting face with a fast

feed in a dense wood. It is also possible to overload the saw gullets in nondense woods by using

excessive feed rates. Hence, the sawyer with

unlimited power at his command must exercise

skill to avoid overloading his saw. This is done

by coordinating the rate of feed with cutting

depths and densities so as to hold the load

within the capacity of the saw or prime mover

to function efficiently. Such coordination is

gained only by testing the capacities of saw or

power in an installation.

Horsepower Requirements

The horsepower required for equipment other

than the headsaw is given in table 2. For headsaw requirements, small-mill manufacturers

usually recommend about 8 horsepower per 100

board feet of hourly production, but this figure

TABLE 2.—Power requirements for equipment

other than the headsaw of a small mill

Equipment item Type

Horsepower

required

Log haul Car and inclined trackway,

friction drive.

Gear drive

6

15

Log conveyor chains

Chain lift from sluice opposite deck.

10

5

on deck.

Log turners Double-bar friction kickers.

Overhead shaft and chain,

friction drive.

Single-bar type, friction

drive.

Rocker-arm shaft type

Heavy type

Light or medium-weight

type.

3

Carriage drive

Carriage setworks.

6

6

15

10

5

3

Carriage dogs. 1

Carriage log unloader 5

Sawdust chain 1

Sawdust blower^ 5

Refuse chain _. _ Heavv tvpe 20

Live rolls _. 5

Transfer and conveyor 15

chains.

Sorter chains _ 5

Edger

Two-saw trimmer

Single-saw, manual type

2- to 3-8aw, 27-inch

2- to 3-saw, 33-inch

4-saw, heavy-duty

5

15

20

100

15

Cut-off saw . 8

Slab cut-off saw 5

is too generalized to fit the variability in transmission and in logs. Tables 3, 4, and 5, based

on Forest Products Laboratory tests, give the
40 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

horsepower used to force a 48-inch circular saw

equipped with nine-thirty-seconds-inch inserted

teeth through the log.

In using these tables as a guide in choosing

power requirements, reference should be made

to the discussion of gullet capacity in this

manual, since gullet capacity can put a ceiling

on the maximum bite per tooth which can be

taken, and consequently the horsepower which

TABLE 3.—Horsepower required for various

depths of cut of a W-tooth, small-mill headsaw operated at 300 revolutions per minute,

exclusive of machine-loss horsepower^

Depth Power needed for

of

bite Carriage

feed

rate

Specific

gravity

of

wood ^

depth of cut of—

per

tooth 10 12 14 16 18

(inches) inches inches inches inches inches

Ft. -per min. Hp. Hv. Hp. Hp. Hp.

0.03 30 0.3 1.4 4.1 6.8 9.5 12.3

.04 40 .3 2.0 4.8 7.7 10.5 13.4

.06 60 .3 3.1 6.1 9.2 12.2 15.3

.08 80 .3 4.1 7.3 10.5 13.8 17.0

.10 100 .3 5.1 8.5 11.9 15.3 18.7

.12 120 .3 6.1 9.7 13.3 16.9 20.4

.13 130 .3 6.6 10.2 13.9 17.5 21.2

.03 30 .4 3.6 6.7 9.9 13.0 16.2

.04 40 .4 5.1 8.5 12.0 15.4 18.9

.06 60 .4 8.0 12.0 16.1 20.1 24.2

.08 80 .4 10.5 15.0 19.6 24.1 28.7

.10 100 .4 13.0 18.0 23.1 28.1 33.2

.12 120 .4 15.5 21.0 26.6 32.1 37.7

.13 130 .4 16.8 22.6 28.4 34.2 40.0

.03 30 .5 5.8 9.4 13.0 16.6 20.2

.04 40 .5 8.1 11.9 15.7 19.5 23.3

.06 60 .5 12.8 17.8 22.8 27.8 32.8

.08 80 .5 16.9 22.7 28.5 34.3 40.1

.10 100 .5 20.9 27.5 34.1 40.7 47.4

.12 120 .5 25.0 32.4 39.9 47.3 54.8

.13 130 .5 27.1 34.9 42.8 50.6 58.5

.03 30 .6 8.0 12.0 16.1 20.1 24.2

.04 40 .6 11.2 15.9 20.6 25.3 29.9

.06 60 .6 17.6 23.5 29.5 35.4 41.4

.08 80 .6 23.2 30.3 37.4 44.5 51.5

.10 100 .6 28.8 37.0 45.2 53.4 61.6

.12 120 .6 34.4 43.7 53.1 62.4 71.8

.13 130 .6 37.3 47.2 57.1 67.0 76.9

.03 30 .65 9.1 13.3 17.6 21.8 26.1

.04 40 .65 12.8 17.8 22.8 27.8 32.8

.06 60 .65 20.0 29.3 38.6 47.9 57.3

.08 80 .65 26.4 33.2 46.0 55.8 65.5

.10 100 .65 32.8 43.0 53.2 63.4 73.7

.12 120 .65 39.2 49.9 60.6 71.3 81.9

.13 130 .65 42.4 53.3 64.2 75.1 86.1

1 Additional horsepower used to run transmission and

feed equipment. Add 4.43 horsepower for transmission,

2 horsepower for feed equipment.

2 Use specific gravity of individual species, as given

for oven-dry material based on volume at time of test

in U. S. Dept. of Agr. Tech. Bui. No. 479, "Strength

and Related Properties of Woods Grown in the United

States."

can be utilized. The rates of carriage feed at

listed bites per tooth are given. Estimates of

actual production per hour based on these feed

rates are not justified. Production should, however, bear a close relation to feed rates and a

power source permitting twice the feed rate of

another should result in slightly less than twice

the production per hour. The additional power

used to run the transmission and feed equipTABLE 4.—Horsepower required for various

depths of cut of a AO-tooth, small-mill headsaw operated at í50 revolutions per minute,

exclusive of m,achine-loss horsepower^

Depth Power needed for

of

bite Carriage

feed

rate

Specific

gravity

of

wood '

depth of cut of—

per

tooth 10 12 14 16 18

(inches) inches inches inches inches inches

Ft. per min Hp. Hp. Hp. Hp. Hp.

0.03 45 0.3 1.8 5.5 9.3 13.0 16.8

.04 60 .3 2.6 6.5 10.4 14.3 18.3

.06 90 .3 4.4 8.7 13.0 17.2 21.5

.08 120 .3 5.8 10.3 14.9 19.4 24.0

.10. 150 .3 7.2 12.0 16.8 21.6 26.5

.12 180 .3 8.6 13.7 18.8 23.9 29.0

.13 195 .3 9.3 14.5 19.8 25.0 30.3

.03 45 .4 4.6 8.9 13.2 17.5 21.9

.04 60 .4 6.7 11.4 16.2 20.9 25.7

.06 90 .4 11.1 16.7 22.3 27.9 33.6

.08 120 .4 14.6 20.9 27.3 33.6 40.0

.10 150 .4 18.1 25.2 32.3 39.3 46.4

.12 180 .4 21.6 29.4 37.2 45.0 52.8

.13 195 .4 23.5 31.6 39.7 47.8 55.9

.03 45 .5 7.3 12.1 17.0 21.8 26.7

.04 60 .5 10.7 16.2 21.8 27.3 32.9

.06 90 .5 17.8 34.7 31.7 38.6 45.6

.08 120 .5 23.5 31.6 39.7 47.8 55.9

.10 150 .5 29.2 38.4 47.7 56.9 66.2

.12 180 .5 34.9 45.3 55.7 66.1 76.5

.13 195 .5 37.8 48.7 59.7 70.6 81.6

.03 45 .6 10.1 15.5 20.9 26.3 31.8

.04 60 .6 14.7 21.0 27.4 33.7 40.1

.06 90 .6 24.6 32.9 41.2 49.5 57.9

.08 120 .6 32.5 42.4 52.3 62.2 72.1

.10 150 .6 40.4 51.8 63.3 74.7 86.2

.12 180 .6 48.2 61.2 74.2 87.2 100.3

.13 195 .6 52.1 65.9 79.7 93.5 107.4

.03 45 .65 11.5 17.2 22.9 28.6 34.3

.04 60 .65 16.8 23.5 30.3 37.0 43.8

.06 90 .65 28.0 37.0 46.0 55.0 64.0

.08 120 .65 36.9 47.7 58.5 69.3 80.1

.10 150 .65 45.8 58.4 71.0 83.6 96.1

.12 180 .65 54.7 69.0 83.4 97.7 112.1

.13 195 .65 59.2 74.4 89.7 104.9 120.2

1 Additional horsepower used to run the transmission

and feed equipment. Add 6.64 horsepower for transmission, 3 horsepower for feed equipment.

2 Use specific gravity of individual species, as given

for oven-dry material based on volume at time of test

in U. S. Dept. of Agr. Tech. Bui. No. 479, "Strength

and Related Properties of Woods Grown in the United

States."
SMALL SAWMILL OPERATOR'S MANUAL 41

TABLE 5.—Horsepower required for various

depths of cut of a íO-tooth, small-mill headsaw operated at 600 revolutions per minute,

exclusive of machine-loss horsepower^

Depth Power needed for

of

bite Carriage

feed

rate

Specific

gravity

depth of cut of—

per

tooth

of

wood ^ 10 12 14 16 18

(inches) inches inches inches inches inches

Ft. -per min. Hp. Hp. Hp. Hp. Hp.

0.03 60 0.3 1.9 6.5 11.1 15.7 20.2

.04 80 .3 3.0 7.8 12.6 17.4 22.2

.06 120 .3 5.4 10.7 16.0 21.3 26.5

.08 160 .3 7.1 12.7 18.3 23.9 29.6

.10 200 .3 8.8 14.8 20.8 26.7 32.7

.12 240 .3 10.5 16.8 23.1 29.4 35.8

.13 260 .3 11.4 17.9 24.4 30.9 37.3

.03 60 .4 4.9 10.1 15.3 20.5 25.6

.04 80 .4 7.7 13.4 19.2 24.9 30.7

.06 120 .4 13.7 20.6 27.6 34.5 41.5

.08 160 .4 18.1 25.9 33.7 41.5 49.3

.10 200 .4 22.5 31.1 39.8 48.4 57.1

.12 240 .4 26.9 36.4 45.9 55.4 65.0

.13 260 .4 29.0 39.0 49.0 59.0 69.0

.03 60 .5 7.8- 13.5 19.3 25.0 30.8

.04 80 .5 12.3 18.9 25.6 32.2 38.9

.06 120 .5 22.0 30.6 39.2 47.8 56.4

.08 160 .5 29.0 39.0 49.0 59.0 69.0

.10 200 .5 36.0 47.4 58.8 70.2 81.6

.12 240 .5 43.0 55.8 68.6 81.4 94.3

.13 260 .5 46.6 60.1 73.6 87.1 100.7

.03 60 .6 10.8 17.1 23.5 29.8 36.2

.04 80 .6 17.0 24.6 32.2 39.8 47.4

.06 120 .6 30.4 40.7 51.0 .61.3 71.5

.08 160 .6 40.1 52.3 64.5 76.7 88.9

.10 200 .6 49.8 63.9 78.0 92.1 106.3

.12 240 .6 59.5 75.5 91.6 107.6 123.7

.13 260 .6 64.3 81.3 98.4 115.4 132.5

.03 60 .65 12.3 18.9 25.6 32.2 38.9

.04 80 .65 19.4 27.5 35.6 43.7 51.7

.06 120 .65 34.5 45.6 56.7 67.8 78.9

.08 160 .65 45.5 58.8 72.1 85.4 98.7

.10 200 .65 56.5 72.0 87.5 103.0 118.6

.12 240 .65 67.5 85.2 102.9 120.6 138.4

.13 260 .65 73.1 91.9 110.7 129.5 148.4

^ Additional horsepower used to run the transmission

and feed equipment. Add 8.85 horsepower for transmission, 4 horsepower as maximum for feed equipment.

2 Use specific gravity of individual species, as given

for oven-dry material based on volume at time of test

in U. S. Dept. of Agr. Tech. Bui. No. 479, "Strength

and Related Properties of Woods Grown in the United

States."

ment of the test mill is given in footnote 1 of

tables 3, 4, and 5.

Classification of Prime Movers by Types

The three types of power used in sawmills

are internal combustion, steam, and electric.

Each can give effective service if not overloaded, and all can be stalled by overloads.

Internal-combustion (gasoline and Diesel) engines and electric motors lose speed rapidly;

steam engines lose speed more slowly. If the

load is not reduced to balance the reduced

horsepower delivery, the motor or engine stalls.

The damage caused by stalling of steam or

internal-combustion units is limited to excessive belt wear and lost production. Stalling can

damage electric motors by burning the insulation off the windings; for this reason, electric

installations should be equipped with a circuit

breaker to shut off current before the ultimate

capacity is reached.

Basis of Horsepower Ratings

A motor, whether internal-combustion or

electric, is given a horsepower rating by the

manufacturer. For internal-combustion engines,

this rating is usually the brake horsepower delivered under ideal conditions and for the

engine speed at which horsepower delivery is

at maximum. This rated capacity should be

reduced by 20 percent when considering power

capacity for sawmill operation. The rated capacity of automobile engines used as power

sources on small mills should be discounted at

least 50 percent, since the rating is for an engine speed greatly in excess of that at which

a mill power unit is run. The manufacturer's

rating of an electric motor is usually from onehalf to three-fourths the maximum horsepower

the unit can deliver. This rating provides a

factor of safety against overheating and damage.

Steam engines and boilers may also be given

a horsepower rating. The engine and boiler ratings are based upon a standard formula. The

manufacturer normally rates the engine at 75

percent of its maximum output as given by the

formula :

Hp. =

PLAN

33,000

Where P

L

A

N

mean effective pressure in pounds

per square inch.

length of piston stroke in feet.

area of piston head accessible to

steam in square inches.

number of strokes per minute.

The boiler horsepower is 100 percent of the

output given by the formula:

TT Total B.t.u. delivered to the water

^P- = 33:479

To drive the type of engine normally used, a

high-speed (175 to 300 revolutions per minute),

single-valve, noncondensing, simple engine, the

rated boiler horsepower capacity should exceed

the engine horsepower rating by approximately

50 to 75 percent.
42 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

Comparison of Types of Prime Movers

A generalized comparison of certain characteristics of the three major types of prime

movers is given in the following tabulation. A

rating of A is the best and C the poorest for a

given characteristic. The indicated relationships do not, of course, universally apply.

Internalcombustion Steam. Electric

engine engine motor

Initial cost B C A

C9st of fuel and

maintenance C B A

Length of service CAB

Ease of moving A C B

Range of adaptability ABC

Field checks indicate that approximately 65

percent of small mills are powered by internalcombustion engines, 33 percent by steam engines, and 2 percent by electric motors, but

that 90 percent of the mills of highest capacity

are steam-powered. The dominance of internalcombustion units in the over-all grouping is

due to the preponderance of portable mills,

which require the ease of moving and range of

adaptability afforded by them. The high-production units are permanent mills where these

two characteristics are immaterial. Electric

units are preferred where high-power current

is available at low rates and steam is not required for kiln drying.

Variants of Each Type of Prime Mover

Diversity exists in internal-combustion units,

electric motors, and steam engines. Internalcombustion units are either spark-ignited and

fueled with gasoline or compression-ignited and

fueled with Diesel oil. For comparable horsepower capacities, gasoline-fueled units usually

have lower initial costs and higher fuel costs

than pressure-ignition Diesels. Repairs are related to running speeds in that the engine producing a given horsepower at comparatively

low speed through relatively large piston displacement normally requires fewer repairs

and has a longer life than one getting the

same horsepower from lesser displacement and

greater speed.

Electric motors are classified as constantspeed, multispeed, adjustable-speed, and variable-speed, but the class usually used at mills

is constant-speed. For sawmill machines, these

constant-speed motors are "squirrel-cage"

wound. Servicing of a properly installed motor

is simple ; it consists of insuring that lubricants

are available for bearings and that bearings are

wholly enclosed.

The classification of steam engines is based

on the number of cylinders through which

steam is successively passed, but steam engines

used on sawmills are usually the single-cylinder,

direct-acting type, have either a simple or a

balanced slide valve, and are controlled by

means of a throttling or an automatic cut-off

governor.

Dutch-Oven Furnaces for Burning Sawdust

Where sawdust is used for boiler-furnace

fuel, an unusually long combustion chamber of

the Dutch-oven type is needed. The installation

is usually too costly unless the mill is operated

full time at one site for at least 2 years.

A grate area of one-third to one-half square

foot per required horsepower is necessary and

provides a basis on which to estimate the furnace dimensions. The grate should be approximately square in order that sawdust fed to the

center of itwill funnel downward and cover all

exposed grates. The firebox over the grates is

arched (fig. 63), and the distance from the

top of the grate to the center of the arch is

slightly greater than the length of the grate.

The distance from the bottom of the grate to

the ash-pit fioor should be at least 18 inches.

The ash-pit floor has a slight upward slope

from_ front to back, and the opening through

the lining at the doors for furnace, ash pit, and

rear increases in area from the doors inward

to facilitate cleaning.

The feed tube, 6 or 8 inches in diameter, is

directly over the center of the grates, and can

be a piece of cast-iron pipe. It extends downward from the deck fioor slightly into the

chamber, and is tightly sealed with the furnace

walls. A cast-iron lid is placed over the top of

the feed hole when the sawdust is not being fed

or when the fire is banked.

The sawdust-burning grates have openings

about one-half as large as those for coal. Sizes

vary, length ranging from 3 to 7 feet and

width from 8 to 11 inches per bar. The grates

are supported at the ends on angle-iron members, and a space of one-half inch is left at each

end of the grate for expansion (fig. 63, ^).

A recommended door arrangement for ash

pit, firebox, and rear consists of a double door

hung to the steel front plate, ash-pit and firebox doors fitted with wood-burning air vents,

and a rear clean-out door in metal framing.

Beyond the grate area, the combustion chamber is fioored to form a ridge and vertically

walled at the sides. The rear is constricted inwardly back of the boiler, as indicated in figure

63, A. The junction of boiler and furnace walls

must be tightly sealed. The furnace walls are

strapped or reinforced with iron members (fig.
SMALL SAWMILL OPERATOR'S MANUAL 43

/¿^.•••• f.v.*--;: :j.i.£±i^^

I I I U I I I I III i I

I

x^.

ál

^:^fMä

' *i'.\'\? •l-r!';A'.f-:il L-*.'i""!>'!'A-'^«ïï*^

CO^C^C^C^^

I M I 111 U,IJ

>v«*N^AV/-^

Ï

LEGEND

^^ £>i/?r// /^/¿íí- ^/p/ff/f

g^?^ CONCRETE ^ggga INSULATION

FIGURE 63.—Dutch oven. A, Side elevation. B, Section through x—y. C, Side elevation showing placement of steel

strapping over insulation.
44 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

63, C). The reinforced-concrete deck floor over

the firebox is about 4 inches in thickness and

mainly supported by steel bars (fig. 63, A).

The inner wall of the combustion chamber

consists of a double (9-inch) thickness of fire

brick laid with dipped and rubbed joints

(mortar not trowelled in place) using fire-clay

mortar. The insulation should be at least 4

inches in thickness.

Usually green sawdust is brought by a trough

conveyor to discharge at a point several feet

above and to one side of the feed hole into a

metal trough leading to the feed pipe in the

furnace. This metal trough is in two unconnected sections, the one ending at the feed pipe

being suspended slightly below the section from

the sawdust conveyor trough to minimize fire

hazard.

BELTS AND PULLEYS

Flat Belts

Flat belts used by mills are made of leather,

canvas, balata, or rubber. All have adequate

strength, but other service requirements may

dictate the choice of material. Canvas or

leather, unless waterproofed, does not stand up

under moist conditions. Balata belting, a mixture of canvas and balata gum, is waterproof

and, although not injured by animal oils, can

be damaged by mineral oil or heat above 100°F.

Rubber belting, a mixture of canvas and rubber

gum, is waterproof but can be injured by

oils. Neither canvas nor balata belts should be

laced. The ends should be joined together with

either metal fasteners or a cemented step joint.

The selection and hookup of flat belts for

efficient power transmission combined with a

reasonable service life are complicated by the

following factors: Belt speed, material, thickness, width, distance between pulleys, tension,

angle of contact, whether horizontal or otherwise, uniformity of loads, whether tight side is

above or below, method of joining ends of belt,

whether belt is kept clean or not, size, material,

and alinement of pulleys.

A flat belt lasts longer if it is kept no tighter

than necessary to prevent slipping. On horizontal drives and with small pulleys carrying

narrow belts, pulleys should be spaced about

15 feet apart and the belt should sag not more

than 2 inches; for larger belts and pulleys, a

25-foot spacing and a 3-inch sag are recommended. When the distance between pulleys is

short or one js placed over the other, belts must

be kept tight. This is done by increasing the

distance between pulleys, shortening the belt,

or using a rider.

Measuring Belt Size .,-

To determine the length needed for a new

belt, measure with a steel tape the course of

the belt around the pulleys. The tape should

be drawn tightly. Cut the belt one-eighth inch

per foot of length short of this measured

length to offset initial stretch, and splice the

endless belt or lace the jointed one. New belts

stretch appreciably, particularly during the

first 3 days of service. If the pulley spacing

can be increased or a rider used, the belt can

be readily tightened. If the belt must be shortened, usually several adjustments are necessary. Catalogs of belt manufacturers give

instructions for belt splicing and lacing.

Splicing and Lacing

To splice a belt, measure the course around

the pulleys with the steel tape and add the

overlap. For new belts, deduct one-eighth inch

per foot ; for used belts take the full measurement. With a knife, separate the plies at both

ends and trim so as to make steps, as shown in

figure 64, of the following proportions:

Width of belt Size of step

' :. (Inches) (Inches)

' > 8 4 \,v,

8 to 12 5

. 14 to 18 6

Over 18 7

Precision is essential, because the steps of

one end must exactly complement those of the

other; a carpenter's square should be used to

mark them off, so that the ends can be cut at

right angles to the belt length. The cut surfaces

must be clean for gluing. The overlapping surfaces of each end are coated with adhesive

(rubber cement for rubber, animal glue for

leather or canvas). Rubber cement is allowed

to dry until tacky; two coats are applied thus.

The stepped ends are then placed together to

FIGURE 64.—Step-trimmed ends of composition belt

ready for splicing. Dots show where rivets will be

located.
SMALL SAWMILL OPERATOR'S MANUAL 45

form a joint. In rubber belts the cemented joint

is clinched tight with 7-gage copper burr rivets.

On leather or canvas belts, hot glue is applied

and the joint is held under heavy weights until

the glue has set before being riveted. Rivet

holes are made with an awl, not with a punch.

To lace a belt with rawhide, mark oflf two

lines parallel to each end at the distances given

in table 6. - • ,;

TABLE 6.—Specifications for lacing flat belts

Distance of holes from

Width of

belt

belt end Size of

lacing (inches)

First row Second row

Inches Inches Inch

2- 4 Yi 1 H

6- 8 ^H %

10-12 M 1» %

14-16 XH ;. K

18-20 - I,- It - : VB

22-24 IK --^ m - - ^

With a belt punch, lacing holes are cut that

are about three-fourths the width of the lacing

used, and are alined as shown in figure 65. Lacing is threaded so that it is parallel to the belt

length on the inner or pulley side of the belt

and crosses on the outer side. The belt ends are

held closely together while the rawhide is

threaded from the outer side of the belt

through the center hole. A, of the series (fig.

65) for about one-half the lacing length, then

straight across through hole B. This brings the

lacing end out at the nonpulley side of the belt.

The lacing end is then brought across through

hole C, and straight across on the inner side

through D. This pattern is continued to the

edge. At holes /-/ the rawhide is threaded

straight across on the inner side twice and

once on the outer side, then continued back to

hole D, the lacing end thus being on the outside

of the belt.

OUTSIDE ^ - PULLEY SIDE

FIGURE 65.—Method of lacing a belt.

471449°—58 4

Next, the other end of the lacing is brought

from hole A through hole E and straight across

to hole F. The same procedure is then followed

as for the other end, arriving finally at ^, on

the outside of the belt. Small holes X and Y are

then punched three-fourths inch from holes D

and A respectively; one end of the rawhide is

laced twice through holes D and X and the other

end twice through holes A and Y. Lacing should

be pulled taut and be free from twists. The ends

are trimmed close to the belt on its outer face.

Metal lacings of the hinged type are serviceable for small-mill belting. The alligator type

can be put on by hammering the barbs into the

belt; the clipper type is installed with a lacing

machine. . ,_ .,,.-...,.

"^:^'' V-Belts . V-belt drives are increasingly used in small

mills. They require short spacing between the

pulleys and a means of adjusting spacing to

assure tightness. The recommended range of

center-to-center pulley distances is not less than

the diameter of the larger nor more than the

sum of the diameters of the two pulleys. Necessary adjustments are made by providing a

means of moving either the drive or the driven

member. Takeups should be provided for at

least 5 percent of the belt length, in addition

to an allowance for putting on the belt.

To install a V-belt, the pulleys should be

seated so that the sheaves are exactly alined.

Either the drive or the driven machine is then

moved toward the other until the belt can be

put on by hand (forcing the belt on with a

screw driver or lever may damage it). The

movable machine is then backed until the belt

is so tight that considerable effort is required

to twist it a half turn when it is grasped about

half way between pulleys. The mobile machine

is then fixed in place.

New belts will stretch—chiefly within the

first 3 days of service—and need tightening.

It is not good practice to put new and used belts

in the same drive. If a belt breaks, and a used

one is not available, all in the set should be

replaced with new ones, saving the unbroken

used ones for replacement of other used belts.

Transmission Capacity of Belts

The capacity of a belt to transmit power

from one pulley to another is limited by its

size and that of the pulleys. Overloads result in

inefficiency through excessive belt slippage, or

in rapid wear of the belts. Tables 7 and 8 present manufacturers' horsepower ratings for

belts of various sizes; capacity of V-belts, as

shown in table 7, is rated according to the
46 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

sheave diameter of the pulley as well as the

belt size. V-belt sizes have been standardized

among manufacturers according to cross-sectional area and identified by letters, such as A,

B, C, D, andE (table 8).

The values given in tables 7 and 8 are for

transmission between pulleys of equal size. If

one pulley is smaller than the other, as often

happens in order to step up or reduce speeds,

the ratings must be multiplied by a reduction

factor that, in turn, depends on the arc of contact between the belt and the smaller pulley.

This arc will be less than 180° ; it represents a

convenient way of expressing the reduced area

of surface contact between belt and pulley.

Since this arc is smaller with smaller pulleys,

less power will be transmitted to or from the

smaller pulley.

The arc of contact of the smaller pulley can

be calculated by a simple formula :

Arc of contact =

180°—

(D—d) 57

Distance between pulley centers (inches)

Where D is the diameter of the larger pulley in

inches, and d is that of the smaller pulley.

When the arc of contact of the smaller pulley

for a given hook-up is found by this formula,

TABLE 7.—Manufacturers' approximate horsepower rating, per inch of width, for standard

flat sawmill belts subject to medium shock

loads, when distance between pulleys is 15

feet or more ^

Belt speed

(ft. per

minute)

Leather belts

Rubber belts.

Single-ply Double-ply

per ply

1,000

Horsepower

1.35

2.01

2.62

3.30

3.90

4.05

4.27

4.42

4.65

4.80

5.03

5.17

5.32

5.40

5.55

Horsepower

2.33

3.45

4.50

5.55

6.54

6.90

7.26

7.59

7.86

8.16

8.49

8.76

9.00

9.23

9.38

Hwsepmver

0.313

1,500,-- .474

2,000 .625

2,.500 .772

3,000 .907

3,200 .945

3,400- --- - . .990

3,600 1.032

3,800 1.070

4,000- 1.110

4,200

4,400

4,600-

1.140

1.170

1.195

4,800 1.220

5,000 1.237

1 Derived from data in catalogs of Chicago Belting

Co. and Manhattan Rubber Co.

TABLE 8.—Manufacturer's horsepower rating, per belt, of five types of standard sawmill V-belts

under mild shock load, when arc of contact is 180°^

V-belt type A V-belt type B V-belt type C V-belt type D V-belt type E

(.V2 by '}k inch) (=;4 by % inch) (J^ by % inch) (11^ by M inch) (IJ^ by 1 inch)

Belt

speed

Sheave pitch Sheave pitch Sheave pitch Sheave pitch Sheave pitch

diameter diameter diameter diameter diameter

(ft. per

min.) Change Change Change Change Change

3

inches

per inch

diameter of

pulley

5

inches

5

inches

per inch

diameter of

pulley

7

inches

9

inches

per inch

diameter of

pulley

12

inches

13

inches

per inch

diameter of

pulley

17

inches

22

inches

per inch

diameter of

pulley

28

inches

Hp. Hp. Hp. Hp. Hp. Hp. Hp. Hp. Hp. Hp. Hp. Hp. Hp. Hp. Hp.

1,000.-- 0.52 0.125 0.77 1.0 0.15 1.3 2.2 0.20 2.8 3.9 0.32 5.2 6.9 0.27 8.5

1,500-.- .75 .205 1.16 1.4 .25 1.9 3.2 .30 4.1 5.8 .50 7.8 10.2 .42 12.7

2,000..- 1.00 .27 1.54 1.8 .35 2.5 4.2 .40 5.4 7.5 .55 10.2 13.2 .57 16.6

2,500... 1.16 .345 1.85 2.2 .40 3.0 5.1 .47 6.5 8.9 .85 12.3 16.0 .70 20.2

3,000..- 1.3 .40 2.1 2.5 .50 3.5 5.8 .57 7.5 10.2 1.02 14.3 18.5 .83 23.5

3,200.-- 1.3 .45 2.2 2.5 .55 3.6 6.1 .60 7.9 10.7 1.07 15.0 19.3 .88 24.6

3,400... 1.4 .45 2.3 2.6 .60 3.8 6.4 .67 8.5 11.1 1.12 15.6 20.1 .95 25.8

3,600... 1.4 .50 2.4 2.6 .60 3.8 6.5 .70 8.6 11.4 1.20 16.2 20.8 1.00 26.8

3,800.-- 1.4 .55 2.5 2.7 .65 4.0 6.8 .70 8.9 11.7 1.27 16.8 21.4 1.07 27.8

4,000... 1.4 .65 2.5 2.7 .70 4.1 6.9 .77 9.2 11.9 1.35 17.3 21.9 1.12 28.6

4,200.-- 1.4 .55 2.5 2.7 .75 4.2 7.1 .80 9.5 12.1 1.40 17.7 22.4 1.17 29.4

4,400-.- 1.4 .60 2.6 2.7 .75 4.2 7.2 .83 9.7 12.2 1.47 18.1 22.7 1.23 30.1

4,600--- 1.3 .65 2.6 2.6 .80 4.2 7.2 .90 9.9 12.2 1.55 18.4 23.0 1.28 30.7

4,800.-- 1.3 .65 2.6 2.6 .80 4.2 7.3 .97 10.2 12.2 1.60 18.6 23.1 1.35 31.2

5,000.-- 1.2 .70 2.6 2.5 .85 4.2 7.3 .93 10.1 12.0 1.70 18.8 23.2 1.38 31.5

1 Derived from data in catalog of L. H. Gilmer Co., Tacony, Philadelphia, Pa.
SMALL SAWMILL OPERATOR'S MANUAL 47

the reduction factor used with values in table

8 for flat belts will be :

Arc of Reduction

contact factor

170° 0.95

160° .90

150° .85

140° .80

Similarly, the reduction factors used with

values in table 8 for V-belts on pulleys of dissimilar sizes are :

Arc of Reduction

contact factor

170° 0.98

160° .95

150° .92

140° .89

130° .86

120° .82

110° .77

100° .72

The values for V-belts in table 8 must also

be corrected when this type of belt is run over

a flat pulley—as, for example, when transmitting power from an electric motor with a Vpulley to a flat pulley. If the V-pulley is smaller

than the flat pulley, its arc of contact will be

less than 180°. Reduction factors are necessary,

therefore, to determine the transmission capacity of the V-pulley. For various arcs of contact,

these are:

Arc of Reduction

contact factor

170° 0.64

160° .67

150° .69

140° .71

130° .73

120° .75

110° .77

100° .72

Although V-belts can be and are used in hookups of sheaved pulleys and flat ones, such

hook-ups normally are not so efficient as those

with all pulleys sheaved. In a hook-up of a Vto a flat pulley, the speed of the grooved pulley

must be at least three times that of the flat one.

The flat pulley should not be crowned, nor

should the center distance between pulleys be

more than the diameter of the flat pulley.

Pulleys

Pulleys are made of iron, steel, wood, or fiber.

The transmitting capacity of a wood pulley is

about 10 percent, and that of a fiber one 20

' < percent, more than that of metal pulleys at

maximum limits, because they slip less. Wood

and fiber pulleys do not, however, hold up as

well at high speeds. Cast-iron pulleys can be

used at rim speeds up to 5,000 feet per minute,

which is the maximum recommended for small

sawmifls. • The face of a flat pulley should be wide

enough to allow about 1 inch of clearance on

each side of the belt. Crowning the face so as

to raise the center by about Vs inch per foot

of face width helps to keep the belt centered.

The vital point about installing pulleys is to fix

them in perfect alinement. The diameter must

be that necessary to maintain the speed relationship required, but very small pulleys subject belts to excessive wear. Diameters less than

6 inches should not be used with thick belts

(five-ply composition or two-ply leather) running at 4,000 feet per minute or more.

The rule used to determine pulley size or

speed relationships is that the revolutions per

rninute of the drive pulley, multiplied by its

diameter, equals the revolutions per minute of

the driven pulley multiphed by its diameter.

Given values for any three, the value of the

fourth can be calculated. To determine the

diameter of a driven pulley when the diameter

and speed of the drive pulley and the speed

required for the driven pulley are known, the

formula is:

Diam. of driven pulley =

diam. of drive pulley x its r.p.m.

r.p.m. of driven pulley

When the unknown value is the revolutions

per minute of the driven pulley, the formula is :

R.p.m. of driven pulley =

diam. of drive pulley x its r.p.m.

diam. of driven pulley

When the unknown value is the diameter of

the drive pulley, the formula is:

Diam. of drive =

diam. of driven pulley x its r.p.m.

r.p.m. of drive

When the unknown value is the revolutions

per minute of the drive pulley, the formula is :

R.p.m. of drive =

diam. of driven pulley x its r.p.m.

diam. of drive pulley

Power ratings are given in table 8 for two

sizes of pulleys for each class of V-belt. To get

ratings for pulleys of intermediate size, allow

for each inch of pulley diameter the amount

shown in columns between those giving ratings. When the diameter of the smaller pulley

exceeds the larger diameter given for a belt

type, use the rating given for the larger diameter.

The following are the smallest pulley diameters (in inches) that should be used with each

type of V-belt listed in table 8: A, 3.0; B, 5.4;

C, 9.0; D, 13.0; E, 21.6. All values given for

diameters of V-belt pulleys are expressed as
48 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

pitch or diameter outside the belt minus the

belt thickness.

Pulleys for V-belt drives are relatively heavy

and therefore act as flywheels, hence must be

expertly balanced.

Shafts and Bearings

Shafting for small mills is usually of coldrolled steel. Table 9 gives essential data related

to shaft size, distance between bearings, and

maximum load limits. ; . x*; ^; ;

TABLE 9.—Maximum recom,m,ended distances

between hearings for various sizes of coldrolled steel shafting, and maximum power

transmitted '

Diameter

of shaft

(inches)

Maximum distances

between bearings ^

Maximum power

transmitted at—

No

pulleys

With

pulleys

100

r.p.m.

300

r.p.m.

600

r.p.m.

VA

IK

1%

1%

2%

214

2%

Z%

Z%

Feet

11.3

11.7

12.7

13.9

15.1

16.3

18.3

20.3

22.3

Feel

6.6

6.8

7.3

8.0

8.8

9.4

10.6

11.8

13.0

Hp.

4.1

4.8

6.9

10.4

15.0

20.0

36.0

58.0

86.0

Hp.

12.3

14.4

20.7

31.0

45.0

61.0

108.0

174.0

258.0

Hp.

24.6

29.0

40.5

62.0

90.0

122.0

217.0

348.0

516.0

1 Data derived, by permission, from Machinery's

Handbook, Fifth edition. New York, N. Y. 1,400 pp.

Illus. 1920. ,„

2 For shaft speeds not exceeding 3,000 r.p.m.

Bearings are usually babbitt metal, but saw

mandrels, carriage wheels, and edgers may have

roller bearings and the trimmer ball bearings.

Making Babbitt Bearings

Bearings are either solid or split. To make a

solid babbitt bearing, cut or melt out the old

babbitt metal cleanly, being careful to free the

retaining grooves or holes of the old babbitt.

The shaft must not only be clean but freed

from cuts or scratches by dressing it with

emery cloth or in a lathe if necessary. Block it

in the position it is to run, centering the box.

Cut pasteboard collars and place them tight

against the shaft at each end of the box, puttying any small opening. Place the shell, and, if

necessary, build a clay crater around the oil

hole to aid in pouring the babbitt. Melt the

babbitt until it flows freely and chars a pine

stick; heating beyond this point may damage

the babbitt.

To avoid excessive tightness, smoke the shaft

until a layer of carbon smudge covers it. Heat

the shaft and box with a blowtorch or otherwise, but avoid burning out the pasteboard

collars. Stir the melted babbitt to get a uniform

mix, and pour it through the oil hole until the

box is full. When the babbitt has set, work the

box off the shaft, drill out the oil hole, and cut

two oil grooves that cross each other under the

oil hole of the box and extend diagonally to

within one-fourth inch of either end of the

bearing. Try out the bearing. If it heats, remove the box and scrape the bearing until trial

indicates the proper fit.

To babbitt a split bearing, clean the shaft

and box as for a solid bearing and fix the bottom half of the box in position on the shaft.

Put shims across the junction of the bottom

and top halves of the box. These shims extend

to the shaft the full length of the box, and

each has two or three notches next to the shaft

to permit filling the bottom half with melted

babbitt. Bolt the top half of the box in position

and enclose the ends. Heat the box and shaft

and pour the metal through the oil hole. When

the metal has set, unbolt the upper half of the

box and separate the two halves by driving a

chisel between them to break the babbitt in the

shim notches. Scrape off uneven spots in the

bearing, put in the oil grooves, and bevel the

edges of the babbitt slightly where the top and

bottom halves of the box meet. In fitting the

box, bolt it in place, using shims to separate

the halves enough to give a cool box.

CARE AND MAINTENANCE OF SAWS

The common types of saws found in the sawmill are the headsaw, the edger, the trimmer,

the cut-off, and the slasher saw. At small mills,

these types are used according to the size of

the mill and the permanence of the set-up. The

headsaw, of course, is indispensable. Edger

saws are quite commonly used at all but the

smallest portable mills, which frequently use

the headsaw for this purpose. At all but the

smallest mills, likewise, trimmer and cut-off

saws are quite generally used. Slasher saws are

in use at fairly permanent mills which must

have a means of cutting up waste for boiler

fuel or for salable firewood.

In the care and maintenance of saws, an

understanding of the types of sawteeth, how

they perform in the cutting operation, and how

they are kept in proper condition for sawing,

is essential. These aspects of saw use and care

are described in the following sections. While

headsaws are considered primarily, the statements are generally applicable to the other

types of saws as well.
SMALL SAWMILL OPERATOR'S MANUAL 49

Sawteeth

In order that a saw may function effectively,

the sawteeth must be spread so as to make a

channel that is wider than the thickness, or

gage, of the saw plate. Two types of teeth are

in common use to meet this requirement. In

the spring-set type, the teeth are bent outward,

alternate teeth in the same direction and adjacent ones in opposite directions. In the swageset type, the plate is spread at the cutting zone

of each tooth.

Spring-set saws are normally used for cross

cutting and swage-set saws for ripping. Springset teeth tend to cut fine sawdust, while swageset teeth, if properly fitted, cut out small chips

rather than sawdust.

In all three classes of headsaw (gang, band,

and circular) the rip tooth is given hook; that

is, the front outline of the tooth, from its point

to the throat of the gullet, lies behind a perpendicular extending from the point to the saw

back in band and gang saws, or behind the

radius to the tooth point in circular saws.

C^oss-cut bands with a spring-set, rip type of

tooth are rarely used for cross cutting logs on

deck. In circular cross-cut saws, the outline has

no hook or a negative one; that is, the radius

from the point coincides with or is behind the

cutting edge of the tooth.

Swage-set teeth may be "solid"—that is, cut

from the plate—or "inserted," fixed to the plate

with special holders. Normally such teeth approximate the degree of hardness of the plate,

but harder teeth or cutting parts are available.

Inserted points of high-speed steel normally

cut several times as much between sharpenings

as do standard teeth. Still harder alloys, usually

shaped to form cutting parts welded or brazed

to solid or inserted teeth, are coming into use.

These normally function for several days or

weeks between sharpenings, but are brittle and

subject to damage from metal or rock, and special equipment is required for sharpening them.

Complete uniformity is lacking for a given

style of inserted point and holder as made by

different manufacturers. In table 10 are listed

the style symbols used by specified manufacturers for a given style. All symbols vertically

in a given column identify interchangeable

products. The difference in styles includes not

only the shape of the gullet, as shown in figure

66, but differences in the holder and tooth, as

shown in the three major variants (fig. 67).

Resistance to cutting increases with chip

thickness and saw speed, with a change from

species of low to those of high density, with

knotty material, with progressive dulling of the

teeth, and with increasing depth of the sawed

face. The effect of these conditions has been

tested (tables 3, 4, and 5, pp. 40, 41). Given adequate power and gullet capacity, sufficient resistance can be built up to cause the saw to

deflect under extremes in any of these condiTABLE 10.—Extent to which inserted-point sawteeth and tooth holders produced by various manufacturers of sawmill saws can he interchanged. Tooth and holder numbers in the same column

vertically are interchangeable. Based on data furnished by manufacturers listed

ManufacturerSaw

part Manufacturer's part number

Atkins Teeth...

Holders.

Teeth...

2

2

2H

2^

2^

2K

2}^

'¿Vi

'¿V2

2^

2J^

2^

2V2

'¿V2

2J^

2H

2J^

"¿Vi

2)^

2y2

3

3

a

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3^

3>^

4

4

4^

4>á

5

5

B

B.D.F.

'C

•C

3D

133

133

Corley 133 22

Holders B.F.

B.D.F.

Disston Teeth...

Holders.

Teeth...

Holders.

Teeth...

Holders.

Teeth..

4>^D

4HD

2

2

2

2

33^

3H

3^

3^

8

8

4

4

m

4^

4}^

4J^

9

9

5

5

13D

'3D

'6

'6

'33

'33

'33

133

ABC

A

ABC

B

ABC

C

I^

50 55

I^

66

44

44

44

44

Hoe '>U

?ñ

Lippert

Ohlen- 1

1

2P

2P

22

Bishop.- Holders 22

Simonds . Teeth...

Holders.

Teeth...

Holders.

Teeth...

2

2

2

2

3J^

3>^

'33^

W2

4

4

4

4

4K

4}^

5

5

B.D.F.2

B.D.F.2

B.F.

B.D.F.

B

B.D.F.

I 3D

13D

'33

'33

1

1

2P

2P

... 44

44

Spear and 4M

ÍV2

—

Jackson Holders.

1 Atkins No. C and Disston No. 3D saws will take No. 33 teeth and holders, but neither Atkins No. C nor

Disston No. 3D teeth can be used with No. 33 holders.

2 B, D, or F teeth will fit either B, D, or F holders, but a saw milled for a given holder by the manufacturer

must be fitted with that holder (holders not interchangeable).

3 Disston "Single Ball Invincible" tooth.

. / ' ' ■■.,;.'
50 HANDBOOK 27, U. S. DEPARTMENT OP AGRICULTURE

NO.B NO 4

FIGURE 66.- -Outline of gullet for common styles of

inserted teeth.

tions. Lacking a knowledge of the force required to deflect a saw under given conditions,

however, guidance on what the saw will take

can be gained only by using the saw.

Factors Affecting Selection and

Operation of Saws

Many factors affect the selection and use of

saws. Among these are saw diameter, which

largely determines the size of log a mill can

handle; saw gage, which varies with diameter

but also to some extent with the density of the

timber being handled; tooth pattern, including

shape of gullets as well as points; and saw

speed. For particular purposes, the buyer should

consult some competent authority on suitable

saw characteristics for his job.

Diameter

The diameter of the saw should be the least

needed to break down the larger logs sawed.

The relationship between saw diameter and the

diameter of the log that can be sawed by the

standard method of "sawing around" the log is

as follows:

Saw diameter Log diameter

(Inches) (Inches)

48 28

52 30

66 38

60 36

Gage , - ,

The extreme range in gage of circular headsaws used under normal conditions lies between

7 and 10, a difference of about one twentysecond inch. Circular saws are usually beveled

from near the collar to the rim, so that the rim

is 1 or more gages thinner than the center

section. For solid-tooth saws, an 8-9 gage (8-

gage center, 9-gage rim) is recommended for

average conditions, with the alternative of a

9-10 gage for saws 48 inches or less in diameter

or for saws 50 to 60 inches in diameter when

run at high rim speed (10,000 or more feet per

minute). A 7-8 gage is generally used for 50- to

60-inch saws subjected to heavy loads, as with

heavy hardwoods, or for feeds exceeding 1/12

inch per tooth. For inserted-point saws, the 8-9

gage can be used on all diameters up to 60

inches, with the alternative of the 9-10 for

saws 48 inches or less in diameter and the 7-8

for saws 50 to 60 inches in diameter.

Teeth and Gullets

Ripping is most efficiently done by a chisel

action and crosscutting by a knife action. Chisel

action is easiest if the tooth tapers gradually

from the cutting edge to the shank. In designing the headsaw tooth, the top face is carried

back from the cutting edge so as to give a

clearance angle of about 12° (fig. 68). The tapered, or cutting, face is carried back from the

cutting edge to make as sharp an angle with

the top face as possible and yet give enough

body to the tooth to prevent noticeable vibraFlGURE 67.—Major variants of style in holders and inserted teeth.
SMALL SAWMILL OPERATOR'S MANUAL 51

tion when cutting. In solid-tooth saws this cuting face normally makes an angle of 30° to the

radius from the tooth point, although where

heavy loads require a stronger tooth this hook

angle may be as little as 15°. Inserted points

are given more hook, approximately 41°. The

rest of the tooth is shaped to provide the maximum gullet space consistent with an adequately

supported point.

,BACK CLEARANCE ANGLE

FIGURE 68.—Design of tooth and gullet, showing proper

clearance and hook angles.

The tooth should be only wide enough to

assure clearance for the blade. Wider teeth put

unnecessary strain on the saw, increase the

chance that sawdust will work out of the gullet,

take more power, and waste more material. In

saws of 7- to 10-gage, at least 3/32 inch in addition to the blade thickness should be allowed;

4/32 inch is commonly used on the solid-tooth

type for softwoods. For hardwoods or frozen

timber, 1/64 inch less than the above-stated

allowances is recommended.

Inserted points, which are narrowed back

from the cutting edge, are not commonly

swaged beyond what is given them by the manufacturer. Repeated sharpening shortens the

inserted tooth, thus continually narrowing the

cutting edge. The new tooth, therefore, has

excessive clearance (5/32 inch) in order to

lengthen its service life. Cutting takes place

not only along the cutting edge but back

along the edges of the lower face for a distance

usually between 3/32 inch and 6/32 inch, depending upon the size of chip taken. Hence

these edges must be carefully machined and

dressed for the job. , -/: -.-., ;V:>v^ :; <;':;

Spacing of Teeth

The gullets of sawteeth must have a curved

outline (angles or corners in the gullet foster

cracks) with an area ample to carry the sawdust, yet with a strong backing to the tooth

proper. The gullet space required to carry the

sawdust limits the number of teeth that can be

put in the saw.

As has been pointed out in this manual, the

capacity of the gullet to carry sawdust may be

a limiting factor in determining power requirements for a saw. A feed rate in excess of

gullet capacity results in miscut lumber and a

jammed saw. Calculations of gullet capacity

are based on the relationship of the cross-sectional area of wood as a solid and that as sawdust when packed up to a condition where

additional sawdust adds undue load to the saw.

It is assumed the gullet area must be twice

that of the wood removed. This is an approximation which does not allow for the variation

in packing quality of sawdust as related to its

density. The cross-sectional area of the gullet

can be measured by outlining the gullet profile

(fig. 66) included under a straight line from

point to point of consecutive teeth on a paper

having lines making one-fourth-inch squares.

Each square thus equals one-sixteenth square

inch. The cross section of the amount of wood

is the bite per tooth multiplied by the cutting

depth.

The bite per tooth for a stated cutting depth

which fills the gullet under the 2 to 1 assumption is found by the formula

2 bites x cutting depth = gullet area

Thus, for a cutting depth of 20 inches and a

gullet area of 2.5 square inches, the bite is

0.0625 inch, which equals 16 teeth per inch of

feed.

The feed rate up to overloading, in terms of

feet per minute, is:

Number of teeth in saw x saw r.p.m.

Number of teeth per inch of feed x 12

For a bite taking 16 teeth per inch on a saw

with 48 teeth running at 550 revolutions per

minute, the feed rate thus is:

^^ ^ ^^^ = 1371/2 feet per minute 16 X 12

For normal work, inserted-point saws have

approximately one tooth for each 3i/t inches of

rim, solid-tooth saws one for each 2^/2 inches.

With fast feeds, gullet requirements raise the

limit for solid-tooth saws to about 3 inches.

Saw Speed and Chip Thickness

The usual instructions that saw speed should
52 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

be no greater out of the cut than can be maintained in the cut are inadequate without consideration of feed rate. Output hinges on feed

rate—the thickness of the chip taken per

tooth—and on saw speed. In small mills, the

feed rate ranges between 1/24 and Vs inch per

tooth. A relatively thick chip is obviously desirable; it gives greater production with less

wear on the cutting edge and corners of the

tooth, and makes coarse sawdust that is less

prone to crowd out of the gullet. At most mill

set-ups, a thick chip also results in more efficient use of horsepower, as indicated by Forest

Products Laboratory test results shown in table

11.

TABLE 11.—Horsepoiver required to cut a 10-

inch depth at similar carriage feed rates but

different saw speeds i and chip thicknesses

Chip thickness at— Total horsepower at—

Carriage

feed

(ft. permin.) 300 600 300 600

r.p.m. r.p.m. r.p.m. r.p.m.

Inch Inch Hp. Hp.

60 0.06 0.03 19.1 20.6

80 .08 .04 23.4 25.1

120 .12 .06 31.9 34.0

1 Saw diameter 50 inches.

A thicker chip results when the number of

teeth in the saw is reduced, when the carriage

feed rate is increased, or when the saw speed

is reduced. In underpowered mills, the carriage

feed rate usually cannot be increased; for

such conditions, a saw with fewer teeth or one

run at a reduced speed should prove more efficient. Given plenty of power, the carriage feed

rate can be increased to the capacity of the

gullets to carry sawdust; for additional increased production, both the carriage feed rate

and saw speed can be increased. The increased

loads resulting from higher saw speeds and

feed rates, however, require heavier small-mill

equipment in carriage and saw mechanism.

Tensioning the Saw

Forces acting to stretch the rim of a circular

saw are (1) centrifugal force, or the outward

pull of the revolving plate; (2) resistance to

cutting; and (3) heating of the saw when gumming it. These are enough to expand the rim

so that the saw will fail to hold to a true line,

dodging or otherwise deviating, unless it is

properly treated. By stretching the midradial

area uniformly—that is, "tensioning" it—the

rim is steadied, so that the saw holds a true

line.

The amount of tension given this midradial

zone is governed by certain considerations. A

large saw requires more tension than a small

one; a thin saw more than a thicker one; a

high-speed saw more than a low-speed one ; and

a heavily loaded saw more than one under light

load. The measure of tension is the extent to

which the midradial zone sags below a straightedge held on the radius when the saw is supported as shown in figure 69. This sag may be

as little as 1/75 inch on small, slow-speed headsaws, or as much as 1/12 inch on large, highspeed ones.

FIGURE 69.—Method of measuring tension in a circular

saw.

Tension is commonly put into circular saws

by hammering' the midradial area with a special type of hammer. As tension is gradually

dissipated or the rim stretch gets out of balance, the saw must be retensioned.

A competent man can acquire the skills of

leveling and tensioning saws. Where and how

much to hammer must always be a matter of

judgment for each tensioning. This can only be

acquired by experience.

1 Tension can also be given by heating localized areas

of each tooth.
SMALL SAWMILL OPERATOR'S MANUAL 53

The tools suggested are a trial mandrel (fig.

70), a hammer bench with running board or

back rest, a 150-pound anvil with crowned face,

a 4- or 5-pound square-faced hammer, a 4- or 5-

pound round-faced hammer, straightedges 10

and 60 inches in length, and a tension gage

(fig. 71). The tension gage is a straightedge

altered to conform to the arc of curvature when

the properly tensioned saw is tested for "drop."

A headsaw gage can be made by dressing the

edge of a thin strip of steel to fit exactly the

arc of curvature of the correctly tensioned saw

when the saw is given the tension test, one end

of the gage being placed about 4 inches from

the bottom of a gullet and the other end about

4 inches from the eye (center hole) of the saw.

Mark one end of the gage so that the same end

can be placed at the rim in all tests. Do not

allow either the gage or the straightedge to

lean from the upright position; press it gently

against the plate.

To put a saw in condition (1) check for

twists, lumps, and other high spots; (2) level

these; and (3) put in the correct tension. The

gage will indicate where to hammer for tension

and when to quit. To get background experience on the degree of uniformity sought in a

properly leveled saw, put a correctly leveled

and tensioned one on the trial mandrel, fix the

M-B3354-F

M-83353-F

FIGURE 70.—Trial mandrel. Pointer indicates whether

saw is properly tensioned when saw is rotated.

Pointer can be raised or lowered with set screw.

FIGURE 71.—Equipment for tensioning a saw. Bench,

anvil, square-faced hammer, round-faced hammer,

straightedge, and tension gage.

pointer so that it barely clears the plate about

1 inch below the base of the gullet, and then

slowly turn the saw, noting the degree of variation in the gap between the plate and the

pointer. Uniformity should be checked at 2-inch

intervals along a radius from the rim to the

collar line.

The trial mandrel must be flawlessly straight

and held true in the bearings ; saw collars must

be perfectly fitted and planed. The rod to which

the pointer is attached should be parallel to the

planed faces of the collars.

To learn how hard to strike a saw for tensioning purposes, spread a film of oil over an

area of a discarded saw and place the saw on

the anvil. Practice striking it until the face

mark left by the round-faced hammer is maintained at a 7/16-inch diameter. This diameter

should never be greatly exceeded; one of %

inch indicates excessively heavy blows. In leveling, blows are ordinarily less severe than in

tensioning.

Put the saw requiring fitting on the trial

mandrel. Turn the saw slowly and, where the

gap between pointer and plate diminishes beyond the standards set up previously, draw a

short chalk line on the plate. Repeat for each

of the concentric circles 2 inches apart. The

result should be a series of marks indicating

areas of high spots. In some cases, high spots

are indicated by particularly bright metal; in

extreme instances the metal may be blued by

heat generated in sawing.
54 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

These marked areas result from lumps and

twists in the saw and must be hammered out.

Before the saw is taken from the trial mandrel, the extent and direction of these high

spots should be confirmed by placing a 6-inch

straightedge against the plate in such a way

that it is centered on a marked high area. By

sliding the straightedge in different directions

over it, the size and shape of the high area can

be correctly delineated and marked.

Put a double sheet of wrapping paper over

the anvil, place the eye of the saw in the

socket with the marked side of the saw up, and

center one of the spots on the anvil. In all

hammering, whether for leveling or tensioning,

move the saw as needed to bring the anvil

squarely under the blow. Circular high spots

can be taken down with either the round- or

the square-faced hammer ; linear areas (twists)

can be properly leveled only with the squarefaced hammer. To level a circular area with the

round-faced hammer, strike blows beginning

at the center of the area and following a line

to the margin. Space the blows about an inch

apart, and taper off on the force of the blows

in progressing to the margin. Place succeeding

series of blows on lines from center to margin,

as in the first case. Exercise care that the blows

are no harder than needed—too heavy pounding

drives the high spot beyond the level condition

and complicates later tensioning. Do not expect

to level the lump completely the first time over

the saw. In using the square-faced hammer, a

second blow is always struck directly óvei: and

at right angles to the first.

For linear areas (twists), center the area

over the anvil and hammer it so that the long

axis of the square-faced hammer is along,

rather than across, the twist. Blows are spaced

about an inch apart. The first line hammered

should conform to the axis of the twist. Follow

up by hammering a series of lines on each side

if the width of the raised area indicates the

need. Do not hammer the area inside the collar

line or the 4-inch zone next to the base of the

gullets at this stage, but level completely the

midzone area.

Having gone over the areas indicated to be

in need of hammering, put the saw on the trial

mandrel with the other face to the pointer, and

mark the high spots as before. Those requiring

leveling are hammered out. Chalk marks are

cleaned from the saw, and the process of remarking and hammering is repeated until the

saw is properly leveled.

The saw is now ready to be checked for tension. With the saw on the trial mandrel, place

the long straightedge firmly across the plate

as close to the diameter as permitted by the

collar. This diameter-wise application of the

straightedge is repeated on six diameters

equally spaced to divide the circumference into

twelfths. The saw is evenly tensioned when the

straightedge contacts it over its entire length

at all checks. The initial checks will usually

disclose high and low areas.

Low areas indicate relatively great tension,

and they should be outlined and skipped when

hammering. The rest of the plate may contact

the straightedge throughout the diameter, or

unleveled lumps or twists may show as localized high spots. Mark and level these twists.

Eventually the straightedge will be completely

in contact except at the low areas.

Inscribe a series of concentric circles centered at the eye, the outer one about 4 inches

from the base of the gullets and the others at

3-inch intervals until within about 2 inches of

the collar line. For saws run at less than 700

revolutions per minute, draw radii to alternate

tooth points; for saws run at hig'her speed,

draw them to each tooth point. The intersections of the radii and the circles are the spots to

hammer.

Place the saw on the anvil as for leveling,

but without the paper cushion. With the roundfaced hammer, strike a single blow at each

intersection, starting near the collar line and

progressing along the radius toward the rim.

Then follow the next marked radius from the

rim _ toward the center. Continue this until

all intersections to be hammered have been

treated.

Uniformity of blows is attained by detailing

to the tensioner the single job of hammering

the plate. A helper at the bench side pulls or

slides the saw between blows, so as to bring

consecutive marked intersections over the

center of the anvil. The saw is moved at a uniform rate in order not to interrupt the steady,

even tempo required for uniformity in hammering. The tensioner stands across from the

bench in the position best suited to the individual for accurate hammering over the center

of the anvil.

The saw is next marked on the opposite face

with the identical pattern of radii and circles,

so that hammering is done directly over targets

on the reverse side. A single blow of like magnitude is given at each marked intersection. The

saw is then placed on the bench and checked

with the gage for uniform tension; areas in

need of further hammering are marked. This

gage check is done by supporting one edge of

the saw on the bench and, with the right hip

and left hand, raising the opposite edge so that

the saw is supported only by the hip and bench

(fig. 69) and steadied by the left hand. With

the right hand, the gage is placed on a radius

exactly halfway between the bench and hand
SMALL SAWMILL OPERATOR'S MANUAL 55

supports, and the degree of conformity between

the gage edge and the saw plate under it is

noted. If the gage touches at the midzone but

not toward the ends, further tension is required

for that area. If the end zones touch but light

shows under the midzone, this area should not

be hammered. Blows are struck at the intersections of radii and circles as before, but only in

those areas showing need of additional tension.

These blows usually are lighter. It is good practice to stagger the second series of blows from

the original ones by placing circles and radii

midway between those marked for the first

treatment.

When the plate fits the gage on all radii, put

the saw on the trial mandrel and again check

the plate for uniformity of flatness by placing

the long straightedge as close to a diameter as

the mandrel nut allows. The plate should touch

the straightedge throughout. If high or low

spots show up, they are usually due to lumps. If

in the rim or collar zone, these can be located

by using a 6-inch straightedge while the saw

rests flat on the anvil. Hammering inside the

collar line or at the rim zone must be done very

carefully and only after thorough checks indicate that other zones are properly leveled and

tensioned.

Alinement of Saw and Teeth

A saw that is properly alined and tensioned

cuts faces without visible scorings. Scoring

wastes both material and power. Tests at the

Forest Products Laboratory indicate that approximately 10 percent more power is used in

cutting scored faces than clean ones. Scoring

results either from a flutter in the rim of the

revolving saw or because holders or teeth are

out of line. The rim flutter may be due to faulty

tension or to faulty alinement of the mandrel or

collars. If the source of flutter is in the saw, a

properly fitted one shows none; if it is in the

mandrel or collar, all saws will flutter. If the

flutter persists, even though the mandrel is

held in place by its bearings, check the fixedcollar alinement. The plane of the shoulder that

bears on the saw plate should maintain, when

the mandrel is turned, a uniform spacing with

reference to a pointer that almost touches the

collar (fig. 72). If necessary, the collar should

be ground.

The alinement of holders and teeth can be

roughly checked by inspection, or more precisely with a side gage (fig. 73). Misalinement

due to inaccurate placement of tooth or holder

can usually be corrected by careful replacement

after the contacts of tooth, holder, and saw are

cleaned with an oiled rag; in more stubborn

cases, they can sometimes he brought into line

(1 ) W

m

MANDREW

FIGURE 72.—Fixed pointer for checking alinement of

mandrel collar.

FIGURE 73.—Tools for alining a saw, including, a, side

gage; 6, side dresser; and c, jointer.

by tapping them lightly on the bulge side while

holding a block against the opposite side. Misalinement due to sprung parts can be determined by inserting a tooth and holder that is in

line with its own setting. If it is out of line, the

tooth can be brought in line by putting a saw

set on the plate just back of the heel of the

tooth and pulling the tooth.

A loose holder can be stretched by placing it

on an anvil and striking a series of blows with

the round-faced hammer at points indicated in

figure 74, repeating this procedure on the opposite face.
56 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

FIGURE 74.- -Small circles indicate where to hammer

tooth holder to stretch it.

Filing Circular Ripsaws

Filing, as an operation, includes sharpening,

swaging, side-dressing, jointing, and gumming.

The method of filing circular ripsaws is determined by the hardness of the teeth. The teeth

of standard solid-tooth saws can be shaped and

swaged with standard saw-fitting equipment,

and cutting edges can be maintained with a file

or emery wheel. Likewise, standard inserted

points differ but slightly in hardness from the

plate and can be maintained by similar equipment. The high-speed-steel inserted points are

not subject to swaging; nor can they be sharpened with a file, but require an emery wheel.

Still harder alloys are shaped for the cutting

parts and welded or brazed to inserted and solid

types of teeth. These require special sharpening

wheels and cannot be swaged.

The teeth of solid-tooth saws can be fitted by

swaging, side dressing, jointing, gumming, and

filing to restore their shape; inserted teeth are

chiefly filed or ground. It is usually unnecessary

to swage inserted points, as the design assures

adequate clearance for the useful life of the

tooth.2

Solid teeth are swaged and usually filed two

or three times, after which their shape is restored by swaging, side dressing, jointing, and

gumming. For swaging, either a lever type of

swage or an upset type is used. The lever type

(fig. 75) draws the front of the tooth out and

2 If swaging of inserted points is attempted with the

upset swage, the teeth should be held in a discarded

plate or section in order to avoid damaging the milled

i'uncture of the plate with the tooth and holder. If the

ever type of swage is used, the anvil must be carefully adjusted to avoid gripping the tooth too far back,

as the hard points crumble or crack under excessive

spreading.

FIGURE 75.—Lever type of swage.

ñattens it between an anvil and die. The anvil is

adjusted to bear squarely on the top of the

tooth, and the die contacts the under face back

of the cutting edge. The die is slightly eccentric, so that, when turned with the hand lever,

it flattens the metal at the end of the tooth.

This swage is usually fixed to a bench for shop

service or, with a slightly different frame, can

be used when the saw is on the mandrel. The

upset swage (fig. 76), battens the point. If the

upset is used, the central tongue should be

above the point and the point inserted in the

slot having convex faces, with the back of the

swage held on a line with the back of the tooth.

A single blow is struck lightly with a 1-pound

hammer. Then, reversing the swage so that the

central tongue is still above the point, the tooth

is inserted in the slot with straight faces and

hammered as before.

After the tooth has been swaged, its sides

may be given uniformity by side dressing them

with a file mounted on a block (fig. 73). Bluntend screws that can be adjusted pass through

this block to keep the file the required distance

from the saw plate; or uniformity can be obtained by using a shaper (fig. 77) to pattern the

sides of the swaged area by compressing the

sides of the tooth between dies.

FIGURE 76.—Upset type of swage.
SMALL SAWMILL OPERATOR'S MANUAL 57

V ^-- ; FIGURE 77.—Tooth shaper. . j ""'^

Jointing, which usually follows swaging, is

done only to bring all teeth to a true peripheral

circle. Before inserted points are jointed, holders and teeth must be tight and in the true

plane of the saw. Jointing is done by bringing

an emery stone or file against the cutting edge

of the revolving saw. The stone, or file, is fixed

to a block or base (fig. 73) and is supported by

the saw-guide bracket. At first it should engage

only the highest teeth ; then it is advanced very

slowly, until all teeth finally engage.

Gumming is done with a power-driven emery

wheel. Usually, provision is made for automatically grinding the desired tooth and gullet

shapes progressively around the saw. Instructions as to proper operation and emery-wheel

patterns are provided by manufacturers.

In using such an emery wheel, burning of the

saw metal must be avoided; that is, the wheel

must not be forced against the metal so hard

that the metal shows a blue tint. This is avoided

by adjusting the emery wheel to grind the gullet lightly at first and not at all directly under

the cutting edge; each gullet should be ground

this way before proceeding. Then the emery

wheel is readjusted to deepen the gullet, and

each gullet is ground until the wheel grinds the

cutting edge of the tooth and completely around

the gullet. Cutting parts of teeth that have

been distorted by filing, wear, and swaging

should be touched up with a properly adjusted

wheel only after the throat and bottom of the

gullet have been ground. ;;^. ííX.; ;^s<r ^x

Gumming with a round file is not usually

practical on headsaws because of the labor involved and the difficulty of maintaining uniformity of tooth shape and spacing.

Inserted points are usually sharpened with a

file or emery wheel without removing the saw

from the mandrel. Three machines are available

for sharpening the saw on the mandrel. One

consists of a frame supporting a standard file

in a position as in hand filing, uniform surface

contact being assured by means of frame supports as the file is pushed across- the under face

of the tooth (fig. 78). The second consists- of a

frame that supports a hand-cranked wheel

faced with file segments, which can be adjusted

to surface the face of the tooth (fig. 79). The

third consists of a frame supporting an adjustable emery wheel to surface the face of the

teeth. Power is supplied through a fiexible

shaft, either by hand-cranked gears or a motor

(fig. 80). All three machines, when properly adjusted, permit facing the tooth squarely; the

emery wheel can be set to grind to a definite

tooth spacing.

FIGURE 78.—File in frame for sharpening teeth.

In filing by hand, individual skill instead of

mechanical guides must be relied on to surface

squarely across the underface on the plane, in

order to give the desired hook uniformly to

each tooth. A round-edge, mill type of file 8 or

10 inches long is recommended. The filer can

work at the top of the saw or somewhat back of

the top. When filing at the top, he stands on the

track side, facing the saw with his shoulders at

about 45 degrees to the saw plane. The file is

pushed full length straight from the shoulder

without dropping the elbows, being held firmly

against the face of the tooth by gripping the

handle with one hand and the point with the

other.

In gaining experience it is a good plan first to

place the file against the face of a tooth so that

the lower edge is free of the throat, noting the

zone of the file face that can be used without

touching the throat. Then take about three
58 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

FIGURE 79.—Tooth-sharpening machine using handcranked wheel faced with file segments.

M-B2121-F

FIGURE 80.—Tooth-sharpening machine with powered

emery wheel.

strokes and note results. Figure 81, A indicates

that the stroke was straight lengthwise of the

file but it was not in the same plane as the tooth

face. This results in a slanting cutting edge

FIGURE 81.—Examples of correct and faulty filing.

A, Faulty filing; stroke straight lengthwise, but not

in plane of saw tooth. B, Faulty filing; stroke not

parallel with plane of tooth face. C, Faulty filing;

stroke made with a rolling motion. D, Correct filing;

file bears equally on all parts of tooth face.

(high corner). Figure 81, B indicates that the

plane across the file was not parallel with that

of the tooth face, which results in decreased

hook. Figure 81, C indicates that a rolling motion accompanied the trust of the file, aggravating the dullness of a beveled face. Filing should

be practiced until consistency is acquired in

stroking the full face, as in figure 81, D.

In actual sharpening, about five strokes are

taken per tooth, but the number is varied according to the requirements of the individual

tooth. Only enough metal is removed to restore

sharp cutting edges. After the face has been

filed, a slight stroke is sometimes made across

the back and the cutting edge is tapped with

the softwood handle of the file to remove the

burr.

When filing the back of the saw, the filer

usually sits back of the saw and facing the

deck, the saw being between the knees. The

work is done at about shirt-pocket height. The

stroke is parallel with the shoulders and more

diflicult to hold true than the straight thrust

used in filing at the top of the saw.

' ". .' .. ^

Filing Circular Crosscut Saws

Trimmer, straight-line cut-off, and slasher

saws function by cutting across the grain.

Teeth are spring-set except that, in hollowground saws occasionally installed for smooth

end trimming, no set is used.

Tooth Patterns and Spacing

To maintain teeth of uniform length, spacing

(point-to-point distance), and shape, the saw

should be jointed, the teeth spring-set and

sharpened, and the gullets gummed. Figure 82

illustrates the tooth forms used when cutting is

done below or above the mandrel. Tooth spacing

is 114. to 1% inches. Tooth form a shown in

figure 82 is developed by dividing the rim into

intervals equal to the desired tooth spacing and

using each interval as the apex of a triangle

having all sides equal. The base of the gullet is

rounded out so that the tooth depth is twothirds the point-to-point distance, and a bevel is

given as shown in figure 82.
SMALL SAWMILL OPERATOR'S MANUAL 59

more than 0.2 inch below the point. Uniformity

in this point of departure and in amount of set

is usually provided for by the mechanism employed.

To sharpen the saw, first file the bevel, preferably with a round-edge file, taking equal

amounts from the front and back in order to

maintain the correct shape, and height, as well

as uniform spacing, of the teeth. The knife edge

extends down from the point one-fourth to onethird inch. For slab and straight-line cut-off

saws, a bevel of 15° on the front and 10° on the

back of the tooth is suggested; for trimmer

saws it should be 25° to 30° on the front and

10° to 15° on the back. The guesswork can be

eliminated by using a gage cut from heavy tin

plate, as shown in figure 83. Between the knife

edge and the base of the gullet, the tooth is filed

straight across sufficiently to maintain the correct outline, and the base of the gullet is deepened and rounded with a round file. Guidance

for uniformity of gullet depth is gained by

drawing a circle centered on the eye, with a

radius not quite to the base of the gullets.

FIGURE 82.—Tooth forms of crosscut saws. Form a is

used if cutting is done below the mandrel. Form & is

used if cutting is done above the mandrel.

Crosscut saws are often sharpened, set, and

gummed with a power-driven automatic sharpener to insure that the correct shape and spacing of teeth are maintained. Many small mills

lack such equipment, however, using files to

sharpen and gum teeth. In filing, the guiding

considerations are to keep the teeth of uniform

length, shape, and spacing. The base of the gullet must be rounded and the face and back of

the tooth beveled.

Several varieties of setting equipment are on

the market that combine either a hammer-andanvil or a vise-and-lever action. For straightline cut-off and trimmer saws, a set of 0.02 or

0.025 inch, and for slab saws 0.03 inch on each

side, is suggested. The set should be started not

FIGURE 83.—Gage for checking front and back bevel on

trimmer saws.

LABOR REQUIREMENTS FOR SMALL SAWMILLS

For any given tree species, the number of

man-hours required per thousand board feet of

lumber produced generally increases with mill

capacity. Table 12, based on detailed Forest

Products Laboratory studies of several operations involving small mills of varying size,

shows the variation in the man-hours per

thousand board feet and in working force from

pond or log yard through the back of the mill.

The relatively low number of man-hours per

thousand board feet given in table 12 for western species is largely due to the larger log sizes

and greater mill power which are prevalent in

the West, that for the eastern white pine to

less complete manufacture (round-edged lumber).

The usual positions for members of crews of

various sizes for circular-headsaw mills is
60 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

TABLE 12.—Mill labor required to produce

1,000 board feet of lumber

Species

Labor per thousand

board feet Number

of mill

Range Average

employees '

Ponderosa pine, redwood, Douglas-fir. _

Eastern white pine

Eastern hardwoods_„-

Southern pine

Man-hours

2.4 to 5.2

3.5 to 5.5

3.3 to 11.7

5.2 to 10.3

Man-hours

3.9

4.5

6.8

7.5

6 to 26

2 to 8

4 to 10

6 to 10

1 Includes pond men and stackers.

shown in table 13. The fireman of a steam mill

is not included. Variations from this general

scheme of manpower placement are common.

Where logs are delivered directly to the deck,

the manpower for log yard or pond is not needed. Mills using the horizontal edger dispense

with the edgerman and tail edger but use a tail

sawyer. Mills with deck and carriage controls

handled by the sawyer dispense with dogger

and setter. If band headsaws are used, a saw

filer becomes essential for any size of crew.

Work Distribution by Crew Size -•

On the two-man crew units, the sawyer and

tail sawyer fill the deck with logs, then saw

them. If edging is done on the headsaw, the tail

sawyer lays aside boards to be edged and piles

edged ones and slabs on racks or dollies. Unedged stock can be collected back of the saw on

about 30 feet of dead rolls, and accumulations

can be loaded onto the carriage and brought

back to the deck for edging. By a second

method, the tail sawyer pushes the unedged

boards toward the deck, making a pile supported by a fence over the husk. By a third method,

the stock is not sawed completely free from the

log but is returned to the deck in reversing the

carriage and then pulled from the log. This is

poor practice, because the shearing usually

leaves a faulty surface for reworking.

To edge on the headsaw, the tail sawyer

helps the sawyer place the accumulated unedged boards on the headblocks, placing the

wider ones on the bottom and setting successive

boards out from the knees, so that the saw line

will take off the required edging. After one side

is edged, the bundle of boards is flopped over

onto the deck skids and replied, the wider ones

again being placed on the bottom. This second

saw line determines the width of the board, and

for softwoods a ruler is useful to insure that the

board is so placed as to result in a product of

standard width as well as square edges.

If the mill has an edger, unedged stock is set

aside until the deck of logs is sawed. For such

an operation the edger should be spaced approximately 6 feet from the rolls to permit such

storage. The sawyer helps the tail sawyer, one

man feeding the edger and the other piling out.

On three-man crew units, the third man divides his time between yarding logs to the deck

and taking lumber and slabs from the back of

the mill to the yard. Edging is usually done on

the headsaw. In operations delivering logs directly to the deck, however, an edger can be

used to advantage, the third man acting as a

tail edgerman and piling lumber and slabs onto

racks or trams.

On four-man crew units, the log yarder can

usually also transport lumber and slabs to the

yard.

With a five-man crew, the fifth man helps the

tail edgerman pile out lumber and slabs. He

may also operate a cut-oif saw on either lumber

or slabs.

With a six-man crew, the sixth man is the

decker, rolling and turning logs and dogging all

but the front dog, this being done by the

sawyer. ,

TABLE 13.—General assignment of positions for crews of various sizes at a circular-headsaw mill

Number

of

workmen

Log

yard or

pond

Decker Setter Sawyer Tail

sawyer

Edgerman

Tail

edgerman

Cutoff

sawyer

Trimmer

Pileout

men

Saw

filer

Night

watch

Millwright

2 1

3 1

2

2

2

2

4

5

2

2

3

6

7

8

-_

9

10

11 1

16 1 1 1
SMALL SAWMILL OPERATOR'S MANUAL 61

With a seven-man crew, the seventh man is

usually placed as setter on the carriage. He may

also operate one or more dogs. The sawyer does

not operate the dogs, but the decker may help

the setter.

With an eight-man crew, the eighth man

operates the trimmer, usually a two-saw

machine.

With crews larger than eight men, the additional members are needed to provide logs to

the deck or pile out lumber at the rear of the

mill. Special service men—filers, millwrights,

night watchmen—are added about as indicated

in table 13, and in the larger small-mill units

the edgerman is relieved of taking boards behind the headsaw by a tail sawyer, and a cut-off

saw operator is used together with the trim-saw

operator.

MILL LAYOUT

Efficient mill layout has much to do with successful sawmill operation. It has a direct bearing on such time-consuming jobs as the handling and piling of logs and lumber and the disposal of refuse. Basic to a well-laid-out mill is

the choice of mill site. This, in turn, is governed

largely by the size and type of mill.

When small portable mills are moved to the

timber, the mill site is preferably located where

the logs can be brought to it most cheaply.

Usually this will be where the log haul is shortest and uphill hauling is at a minimum. A further requirement is that the lumber outhaul be

feasible. Within this frame the site is chosen

with an eye toward minimizing the work of

leveling up the mill and providing a suitable log

and lumber yard. Beyond avoidance of rocky,

stumpy, wet, hummocky, or very steep sites,

local conditions may be advantageously utilized

to varying degrees. Steam-powered mills must

tap water supplies. Those using hand-pushed

trams to the lumber yard should be so located

as to permit a level or slightly down-grade tram

line ; a slightly down-grade slope from log dump

to track is also favored. A steep down slope on

the track side of the mill aids in slab and sawdust disposal.

Permanent and semipermanent small mills

are usually located at points where favorable

living conditions for labor are combined with

good shipping facilities or local outlets for the

products, including so-called wastes. Local considerations may be the relative cost of the site,

taxes, convenience to labor supply, access to a

railroad siding, public roads, or water transportation, and ample space for log and lumber

yards.

Log Yards and Ponds

Small mills try to balance log deliveries in

such a way that the highest possible proportion

will be unloaded directly on deck, in order to

save pick-up costs. The deck skids extend back

from the carriage tracks about 20 feet to a gap

for the delivery road, then continue for another

20 feet. .., . .,, >

If logs must be yarded, the simplest way is to

unload them directly on the ground, rarely piling them higher than the bunk of the transporting vehicle. Logs are seldom segregated by

species or other characteristic. A space approximately 3 feet is allowed between the ends of the

longer logs of adjoining piles, and the unloading faces of a series of piles are kept abreast,

so as to be accessible for subsequent loads. Poles

supporting the logs hinder the movement of

vehicles bringing logs to the dumping point or

subsequently transporting them to the mill

deck, and are not normally used.

Equipment of the types shown in figures 84

and 85 is often used to pick logs off the ground.

Mill operators and loggers have developed various other machines for this general purpose.^

Where the truck derrick (fig. 86) is used, poles

expedite the loading of logs, the vehicle backing

between the poles. They are placed about 7 feet

apart and are sunk into the ground to elevate

the bottom logs about 6 inches off the ground.

About 300,000 board feet per acre can be

stored in piles averaging 5 feet in height.

At permanent mills these and other methods

are used. A system of skids that spills logs onto

a tram car can be installed (fig. 87), a derrick

can be erected for bunching the logs in high

piles (fig. 88), or the logs can be stored in

water.

Streams, lakes, and ponds can be used for

logs that float, and large quantities may thu^l

held for a year or more without serious degrade.

About 150,000 board feet can be floated per

acre.

Relatively small ponds holding but a few

hours' supply are used for species that sink as

well as for floaters. The purposes of-this ponding are to wash grit and abrasives from the

logs, thaw frozen logs, and provide a practical

means of separating and feeding logs to the

ä Results of a continuing survey of woods and mill

handling equipment by the Forest Products Laboratory

are available to mill operators as published in the

Laboratory's Equipment Survey Notes, which are

issued from time to time.

471449° -58-
62 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

FIGURE 84.—Tractor with rack for yarding logs.

M-68249-F

mill. Such ponds are either blocked oíF from

larger water bodies or are constructed at the

mill site. The conditions sought, in addition to

stable water levels, are a pond width permitting

all logs to be reached from the margin with long

pike poles, a depth limited to adequate log floatage, and a length to contain the required log

volume. For logs not more than 16 feet in

length, a 20-foot width, a 5-foot depth, and a

length of between 50 and 150 feet are suggested. The sides are vertical and are stabilized bycribbing, planking, or concrete. A spillway that

safely carries oiï excess water can be built of

timbers or concrete, and gates or outlet pipes

are provided for draining when cleaning is required. In the northern States, ponds are maintained above freezing temperatures by diverting exhaust steam into them; or cold water is

pumped from the pond over pipes or tanks heated by the refuse burner, and then returned to

the pond.

The dump ramp extends along one side of the

pond, and a dry-storage ramp can be built at

the opposite side. The storage ramp is a duplicate of that shown for use with a track and

tram car (fig. 87). Capacity is increased if the

road along the outer edge of the ramp is

elevated.

Logs are conveyed from pond to deck by

means of trams, conveyor chains, or sling

chains. Cable-pulled trams operate on inclined

tracks that are extended under the surface of

the pond, so that logs can be floated onto the

car bunks. Conveyor chains transporting the

log lengthwise consist of heavy links 8 inches

long, made of iron 1 inch thick, to which are attached log dogs at intervals of 4 feet. The chain

runs in a trough and extends from slightly below the surface of the pond to the back end of

the deck. A less expensive device suited to

small-mill production rates employs a jackladder to hoist logs sidewise (fig. 89).

Another device employs sling chains about 8

feet apart having links about 4 inches long. The

pond slip is extended opposite and parallel to

the deck. One end of each chain is anchored to

the deck and the other is fastened to a shaft

above deck level. Chains of ample length are

used to provide a sling reaching below water

level. The shaft is powered by a friction wheel

(fig. 90). A log is floated endwise over the

slings and hoisted to the deck when the shaft

is rotated. When the friction wheel is disengaged, the sling drops back to receive another
SMALL SAWMILL OPERATOR'S MANUAL 63

FIGURE 85.—Truck with lift arms for yarding logs.

Lumber Yard Layout

Green lumber, unless treated with chemical

fungicides and insecticides, cannot be kept long

without seriously deteriorating, principally in

the sapwood. The speed and extent of deterioration depend largely on temperature, because

fungi and insects are active during warm

weather, less active during cool weather, and

dormant in extreme cold. When wood falls below 20 percent in moisture content, fungi cannot develop, and it is less attractive to most insects. Consequently one way to avoid fungus

and insect attack is to dry the lumber quickly,

particularly the surfaces, to a moisture content

below 20 percent.

The product of small sawmills is seldom kiln

dried ; seasoning is done, if at all, in an air-drying yard. The yard should be easily accessible

from the mill, on ground suitable for hauling

and pile foundations, and open to air currents

for lumber drying. Good air circulation and soil

drainage, a soil that drains quickly, and a level

or slightly rolling surface are essential to meet

these needs. Uneven or steeply sloping surfaces

require excessive cribbing for pile foundations

and grading for roads.

The ground should be kept free from debris

and vegetation. Debris harbors fungi and insects and interferes with air movement. Vegetation restricts air movement over the ground

surface and from beneath the lumber piles.

When the vegetation becomes dry it creates a

fire hazard. Vegetation can be kept in check by

cutting, or can be killed with chemical weed

killers.

A road or an 8-foot fire line around the margin of the yard is kept cleared of vegetation as

a check against encroaching fires. Where organized fire protection is not available, water

barrels and buckets should be placed according

to a planned pattern; for example, at the beginning and end of every fourth row. Adding

3 2/5 pounds of calcium chloride per gallon
64 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

FIGURE 86.—Truck derrick for yarding logs.

will prevent freezing of water at temperatures

down to -20°F.

In general, yard layout should provide for

wide alleys and ample space between piles to

insure good air circulation and adequate room

for handling and hauling lumber. Main alleys

should be 16 feet wide for motor truck or dolly

hauling and hand stacking, or 30 feet wide for

fork-lift truck hauling and piling. The spacing

between main alleys for hand-stacked piles is

twice the length of a pile plus a rear alley of 6

feet or so, making a total of about 38 feet. With

unit-package piles, stacked by fork-lift truck,

the space between main alleys is optional, depending on the number and width of the piles in

the rows and the space between them. Cross alleys should be 16 feet wide for motor truck or

dolly hauling, or 30 feet wide for fork-lift truck

hauling, and spaced about 100 feet apart to give

ready access to main alleys leading to all points

in the yard.

For hand stacking, it is suggested that the

piles be 6 feet wide and about 10 feet high, with

a space of about 21/2 feet between the piles. Unit

packages for yard drying are generally about 4

feet wide, and are stacked three to five units

high. A space of about 2 feet should be left between the piles of unit packages in a row, and

3 to 4 feet between rows.

Piling and Sorting Lumber for Air Drying

The degree to which it is practical to improve

air-drying practice varies from mill to mill. In

general, the larger the mill, the more exacting

its practices, such as piling of stock according

to species, grade, thickness, length, and width.

Permanent mills can also do more in the way of

improving drainage, grading, and pile foundations.''

The total number of piles necessary for a

given operation depends, of course, on production rates and seasoning time allowed, as well

as on sales. The total number of piles open, or

in the process of building, at one time depends

mainly on how closely the lumber is segregated

* Mathewson, J. S. The Air Seasoning of Wood. U. S.

Dept. Agr. Tech. Bui. No. 174, 56 pp., illus. 1930.
SMALL SAWMILL OPERATOR'S MANUAL 65

FIGURE 87.—Skids and trackway for yarding logs.

according to species, size, and grade. Inventory

and shipping are benefited by putting in a

separate pile each item that has a different

market rating, but piling costs and exposure

degrade are thereby increased.

Each operator must determine the degree of

segregation he can afford to follow. Different

thicknesses are, in general, separately piled.

Different species are separately piled if sold on

a species basis. Hardwoods of different lengths

and widths are usually placed in the same pile

and may be separated according to grade. A

common practice at small hardwood mills is to

pile No. 1 Common and better separately from

No. 2 Com.mon and poorer.

Small mills cutting softwoods often separate

stock by width, except that the 3-, 4-, and 5-

inch stock is piled together; and at least partially according to length and thickness. Rarely

is softwood lumber piled according to grade.

One practical method for softwoods is to place

the 8-, 14-, and 16-foot lengths in one pile, and

the 10- and 12-foot lengths in another, thus

making so-called "sorted-length" piles. Grade

separation can be practiced to some extent for

softwood yarding at small mills by box piling

the high-grade items, putting all lengths and

widths of a given upper grade group in one pile,

and piling the lower-grade material separately

according to width and length.

Labeling of piles as to contents helps in identification and inventories. It can be done by surfacing a sticker edge with a knife and writing

with a soft crayon the pile number, species,

item (width, thickness, and grade), piling data,

and footage, thus : No. 65 ash - 4/4 No. 2 Common - 3/5/50 - 3,240. The footage is an estimate made either when the pile is completed or

at the first inventory afterward.

Pile Foundations

The foundations should be mechanically

strong, and sufficient to raise the first course of

lumber at least 18, inches from the ground.

Piers, posts, or blocks make a more satisfactory

foundation support than cribbing, because the

foundation is more open for air movement beneath the pile. For permanent yards, piers of

concrete, masonry, or posts that are of a decayresistant species or pressure-treated with a
66 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

FIGURE 88.—Derrick or jammer for high-piling logs.

preservative, make excellent supports. Piers or

posts set into the ground should extend below

the frost line. Posts or blocks may rest on sleepers or mud sills placed on the ground surface.

At portable operations a reasonably sound log

of low value can be cut into sections to provide

posts or blocks. The tops of each pair of supports should be surfaced or cut so that they are

on a level, and are on a slope of 1 inch to the

foot or on a level in a lengthwise direction.

The rest of the foundation consists of stringers and cross beams, or of cross beams only

(fig. 91). Stringers, generally 6 by 8 inches in

dimension laid on edge, are placed on the tops

of the piers, posts, or blocks (See fig. 93, A).

The stringers run lengthwise of the pile and

follow the slope. Cross beams, generally 4 by 4

or 4 by 6 inches in dimension, are laid on the

stringers, or on the top of the piers, posts, or

blocks, where stringers are absent. Where

stringers are used the number of piers, posts,

or blocks can be reduced. Stringers also permit

more flexibility in the positioning of the cross

beams, so that with piles of different lengths,

FIGURE 89.—Jackladder for hoisting logs sidewise from

pond to deck. , _ ,. , "

the cross beams can be placed to support the

vertical tiers of stickers.

Foundations for unit-package piles are usually level in both directions. Stringers cannot be

used except where the rows of piles consist of

two piles only. A satisfactory foundation for

unit-package piles consists of cross beams, 4

feet apart, supported by piers, posts, or blocks ;

a central 8-foot space is left clear for the entrance and exit of the fork-lift truck by omitting the central cross beam. A removable and

replaceable device carrying a cross beam or its

equivalent should be used to support the center

of the pile (fig. 92). This support is put in place

when the particular pile is made, but is removed to allow the fork-lift truck to approach

piles nearer the center of the row. Such a support may be a sawhorse or a cross beam with

legs.

Pile Construction

For air drying, it is almost universal practice

to pile stock flat, so that most of the weight

bears on the wide faces, not on the edges or

ends. A flat pile may be level both crosswise

and lengthwise, or level crosswise and sloped

lengthwise. With this method of piling the drying rate is relatively slow, but the weight of

the pile tends to keep the stock from warping.

It is therefore suited to species that are likely

to check or warp, and less suited to species that

are likely to suffer from sap stain. Flat piles

may be hand stacked, in a continuous pile, from

bottom to top, or may be made up of several

unit packages separated by bolsters. Hand-
SMALL SAWMILL OPERATOR'S MANUAL 67

FIGURE 90.—Sling-chain log hoist from pond to deck.

stacked piles may be square at both ends, such

as a box or sorted-length pile, or the board ends

may project or overhang at the rear or at both

ends. To prevent excessive warp, it is desirable

either to sort for length or to box pile so as to

eliminate overhanging ends.

For lumber that is susceptible to sap stain,

special piling methods that promote rapid partial drying are sometimes used. These are

known as end piling, end racking, and crib

piling. Each of the methods is described in a

later section of this manual.

To obtain rapid drying with end piling, wide

spaces should be left between boards. End piling, though easily done by one man, causes nonuniform drying from top to bottom, and severe

end checking and surface checking in the upper

parts of the boards, particularly in thick stock.

End racking causes rapid drying, with excessive checking and warping if the drying is allowed to progress very far, but is suitable for

fast partial drying for such purposes as getting

M-9&08B-F

FIGURE 91.—Box pile of random-length hardwoods, supported on sections of logs and cross beams.

the stock dry enough to prevent blue stain;

thereafter the stock should be flat piled to minimize checking and warping. End-racked boards,

however, are likely to blue stain where they

cross. Crib piling also induces fast drying, and

is therefore useful for partial drying but may

result in excessive stain where the boards cross,

as well as warping.

Sorted-Length Piling

Sorted-length piling, which closely resembles

box piling, is suggested for softwoods. To make

such a pile, lay a sticker over each cross beam

and place the first course of boards so that the

front end of each board is flush with the front

edge of this sticker. Space the boards in this

course 2 to 3 inches apart; if two or more

lengths are included in the same pile, place the

longest ones in the outside tiers, and interspace

other long ones regularly in the course to give a

well-supported pile. Succeeding courses duplicate the first, or base course.

The front of the pile should pitch toward the

main alley, 1 inch to the foot of height. Each

tier of stickers should be alined parallel to the

front one. Stickers within a tier should be directly above one another except for the slight

progressive oflfset required to follow the pitch

of the pile. The front of the pile should be free

of projecting ends that would catch water and

cause it to flow into the pile. If the boards are
68 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

M-e3684-F

FIGURE 92.—Unit-package pile foundation, consisting of a central support and two benches across which are laid

cross beams.

of uniform lengths and the piling has been well

done, the rear of the pile will also be free of

projecting ends.

Box Piling t"-' ^-- ' ;":"::•

Box piling is suggested for hardwoods. To

make a box pile, lay a sticker over each foundation cross beam and place a full-length board in

each of the outside tiers. If enough stock is

available for more than two full-length boards

to the course, intersperse long boards regularly

in the course. Place shorter boards in the inside

tiers, with their ends alternately flush with the

front and back of the pile. Each tier is approximately 12 inches in width ; thus it can contain

an 8- and a 4-inch board, or two 6-inch boards.

One end of each board can rest on the sticker at

either end of the pile (fig. 93). Tiers should be

truly vertical, 4 to 6 inches apart. The front of

the pile should be given a pitch of 1 inch per

foot of height. This method of piling results in

vertical flues that allow a free downward air

flow from the top to the bottom of the pile. Both

ends of the pile should be square, with no projecting board ends.

Unit-Package Piling

Unit-package piles are composed of 3 to 5

unit packages, placed by fork-lift truck. The

unit packages are made up at the rear of the

mill, using methods similar to those recommended for flat piling. They are hauled to the

yard by fork-lift truck and built into piles (fig.

94). Good sticker alinement and uniform spacing are essential in unit packages of lumber, in

order that good alinement of cross beams, bolsters, and tiers of stickers can be attained in

the yard pile of unit packages. Piles of unit

packages do not ordinarily have either slope or

pitch.

Stickers

Stickers are used to separate the courses of

lumber in piles. "Stock" stickers are narrow

boards of the same lumber as the pile. Such

piles are commonly called "self-stickered." Self

stickering may be justified with low-value lumber, where degrade suffered through staining

and checking is not important. "Special" stickers for lumber up to 8/4 in thickness are gen-
SMALL SAWMILL OPERATOR'S MANUAL 69

FIGURE 93.—Method of placing boards in box piling.

A, Method of laying up on foundation; B, top view

showing board placement according to length.

FIGURE 94.- -Building a unit-package pile with a

lift truck.

forkerally made of nominal 1-inch stock, rough or

dressed. Stickers for thicker lumber may be

about IV2 inches thick. Special stickers for

hardwoods are generally about 1 inch thick by

11/0 to 2 inches wide, and for softwoods 1 by 2

or more inches. Special stickers should preferably be of air-dry heartwood. At small portable

mills, edgings that have been air dried provide

relatively cheap and satisfactory stickers.

Stickering of unit packages of lumber follows

the same rules as stickering of hand-stacked

piles, except that the narrow width of the packages rules out the use of stock for stickers.

Pile Roofs • -

If yard piles are not roofed the upper

courses of lumber are likely to deteriorate

enough to cause a drop in grade and hence

value. The roof should protect the pile from

sunshine and precipitation and should be reasonably tight. A common type of pile roof is

one composed of a double layer of low-grade

boards. The roof should be pitched so that most

of the water will run to the rear end and drip

off. If the lumber pile slopes 1 inch per foot

from front to rear, the pitch of the roof can

follow the slope of the pile. If the pile is not

sloped, the roof should be supported so as to obtain the required pitch.

For a sloped pile the front roof support can

be made by placing three 2 by 4's laid flatwise,

with the center and rear supports made up of

two 2 by 4's. A double layer of boards is laid on

the center and rear supports, with the boards

of the upper layer overlapping those in the lower layer. This procedure is repeated for the

front part, allowing this part of the roof to

overlap the rear portion. The roof should project beyond the pile, about 1 foot at the front

and 21,4 feet at the rear. In windy regions, tie

pieces wired to the pile should be placed at the

front, center, and rear, to keep the roof boards

from blowing off.

End Piling

Lumber piled on end is equivalent to an upended flat pile. Boards for end piling should be

grouped according to length. With randomwidth stock, like widths should be placed in the

same row, or up-ended tier. In its simplest

form, end piling requires a floor, a central rack,

and strips or some other device to support the

stickers (fig. 95, A).

The stickers must be placed and held until

the two outer boards of a course are placed.

Strips for supporting stickers can be dispensed

with if the piler is provided with a sticker hold-
70 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

er, consisting of a handle adequate to reach the

height desired for placing the sticker, and one

or more cross arms each approximately 3 feet

long. The sticker resting on the cross arm as

easily boosted into place. Then, while the handle

end of the tool is supported on the base, the

piler places the outside boards of the next

course against the sticker, thus permitting removal of the holder.

The floors should be of latticed construction

and should support the lumber at least a foot

above the ground. The central rack should be

sturdy. Piles are generally built up in two directions from the rack, but occasionally in one direction only. The piles are usually about 10 feet

wide, 75 to 100 feet long, with an 8-inch space

between the rows of boards.

End Racking

In end racking, two rows of boards placed on

end are crossed like an X, or preferably form

an inverted V (fig. 95, B). The boards are supported by a ridge pole, and the lower ends

should be supported about a foot above the

ground. If the boards are to be crossed at their

top ends, different racks will be needed for different length stock.

The stock dries rapidly, and 3 to 15 days of

drying, depending on the weather, should be

sufficient to prevent staining. After this period

the lumber should be ñat-piled or shipped, to

prevent excessive checking and warping in the

end-racked pile.

Crib Piling

Crib piling, used by some small mills cutting

southern pine, eliminates foundations, stickers,

and pile roofs, but requires excessive yard

space. Separate piles are made for each length

by cribbing three tiers in the form of a triangle

(fig. 96). The first plank rests on supports at

each end; one end of the second plank crosses

the first above a support and the other end rests

upon the third support of the triangle ; and the

third plank closes the triangle. In succeeding

//

FIGURE 96.—Supports for A, end piling and B, end racking.

M-19870-F
SMALL SAWMILL OPERATOR'S MANUAL 71

courses this crib rack is carried to a height convenient for one-man stacking. The drying rate

is like that of end-racked lumber, and if excessive checking and warping are to be avoided

the cribbed lumber should be taken down and

flat-piled after 3 to 15 days.

Occurring in lower part of pile only:

Provide short chimneys 1/3 or 1/2 height

of pile.'

Use thicker stickers in lower part of pile

only.

1 Does not apply to piles less than 6 feet wide.

FIGURE 96.—Crib piling.

Refinements in Flat-Piling Practice

In flat piles the drying rate and consequent

degrade by blue stain, decay, checking, and

warping are likely to vary with the location of

the pile, the species of wood, and the season.

Therefore, where there is need to reduce checking, warping, blue stain, or decay, the following

refinements in piling practice may profitably be

considered.

To reduce checking—

Lower the foundations ; decrease the spacing

between boards and between piles.

Use thinner, narrow stickers. Place end stickers so that they project beyond ends of

pile.

Use end coatings.

Use sun and wind shield.

To reduce warping—

Use a sufficient number of stickers, of uniform thickness, properly alined and supported.

To reduce blue stain and decay—

Occurring throughout the pile :

Raise the foundations; increase the spacing between boards and between piles.

Provide one central flared chimney or a

series of narrow chimneys.'

Narrow the piles.'

- ^' Dipping Tanks

Treatment of green lumber against blue, or

sap, stain sometimes includes passing the material through a spray of the chemical solution,

but the usual method is to dip the stock in the

solution. Figures 97 and 98 show details of two

kinds of dipping tanks.

The gravity dip tank shown in figure 97 is

placed alongside the rolls and immediately beyond the swing-trim saw. Boards to be dipped

are started down the inclined skids by the trimsaw operator. The slope and length of the skids

are such that the boards being tipped off the

rolls push the boards farther along through the

liquid and up the discharging side. Excess hquid

drains off the board and into the tank as the

board emerges and before it drops to the skids

at the discharging side.

The conveyor-chain type (fig. 98) is usually

so placed that the lumber is conveyed through

the tank and to the sorter chain. Power for

driving the conveyor lugged chains, when applied to the sprockets on the shaft at the entering side of the tank, insures, together with the

rider wheels, that the chain and conveyed material will be submerged.

Strap iron 3 inches wide is fastened to the

tank under the chains to prevent excessive

wear. The tank is floored with a double layer of

1 by 6 tongued-and-grooved material staggered

so that the tongue and groove of one layer centers the board of the other layer. The rider

wheels (iron pulleys) are on a hinged frame

supported above the tank (fig. 98).

Least waste of liquid results when the speed

of the chain is the minimum required to move

the stock; 30 feet per minute is suggested for

mills with a capacity up to 2,000 board feet per

hour. Approximately 130 gallons of liquid will

suffice to keep the dip to the level shown, and

the tank should have outlets permitting draining and cleaning. A mixing tank of at least 50-

gallon capacity and a shelter complete the

equipment.

End Coatings

Since wood dries faster from the end grain

than from the side grain, some kinds of wood,

especially in thick sizes, may check and split at

the ends during air seasoning. For this reason
72 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

Tt 9 9 9 ¡i- =^

TANK^

,ROLLS^ ROLLÍ

ij» . ■■» % » g> i», » <g>i, »=l SOLUTION 4

BELOW TOP

2 4'

SIDE VIEW

ofTTAm^ ^,^.

n

^a

14'

TOP VIEW

Y I j PIPE

If II

II ll

FIGURE 97.—Gravity dip tank.

it is often advisable to coat the ends with a

moisture-resistant end coating when wood is

being seasoned.

Some coatings are liquid at ordinary air temperatures and can be applied cold. Others are

solid at ordinary temperatures and must be

heated before being applied. Either hot or cold

coatings are effective for drying temperatures

up to 140°F., but for temperatures between

140° and 170°F. hot coatings should be used.

Two good cold coatings are hardened gloss oil

thickened with barium sulfate and magnesium

silicate (very cheap), and high-grade spar varnish and barium sulfate (expensive).

The gloss oil should be of a thick grade, made

up (by a paint manufacturer) of about 8 parts

by weight of quick lime, 100 parts of rosin, and

57.5 parts of mineral spirits. To 100 parts of

the gloss oil, 25 parts barium sulfate and 25

parts of magnesium silicate are added. One or

two parts of lampblack can be added if a black

coating is desired. Any paint manufacturer can

make this coating, or the user can mix it as

needed, if the proper grade of gloss oil is at

hand. Some gloss oils have little moisture resistance, and it is therefore necessary that the

coating be made up according to the formula

given above.

FIGURE 98.—Conveyor-chain dip tank.

Paraffin, at 150°F., is a satisfactory hot coating for use on material that is to be air seasoned, but its melting point is too low for use on

stock to be kiln-dried. Other hot coatings are:
SMALL SAWMILL OPERATOR'S MANUAL 73

60 parts by weight of 213°F. coal-tar pitch

mixed with 25 parts of 155°F. coal-tar pitch and

15 parts of 225°-235°F, asphalt; or 7 parts of

lampblack mixed with 100 parts of rosin. Hot

coatings can be applied by dipping the ends of

the stock 1/^ inch into the hot material or by

holding the ends against a power-driven roller

party submerged in the coating.

SAMPLE PLANS OF MILL LAYOUTS

In the following sections sample mill layouts

are presented for circular headsaw mills of unsheltered, temporarily sheltered, semi-permanent types. The smaller band mills may be

housed in a one-story structure based at ground

level by using a pit, but preferred practice calls

for a rigidly supported structure well above

ground level.

Wheel-mounted mills require so little site

preparation that they usually can be economically operated for as little as 5,000 board feet at

a set. The problem is less one of mill setting

than of slab, sawdust, and lumber disposal.

Some types of such mills are stabilized in working position by means of jacks; others require

no supports other than for the truck wheels.

Detailed instructions on fixing parts together

for efficient operation are outlined in the discussion of plan 1 that follows, and can be followed in using the layouts described for plans 2

through 5. Obviously, modification of such instructions or of plan details will be required to

meet special needs or conditions.

Setting Up an Unsheltered Ground Mill

According to Plan 1

Operators cutting up to 200,000 board feet at

a set customarily put the mill directly on the

ground and provide little or no shelter. This

type of mill is shown in plan 1 (fig. 99).

The three essentials in setting up a ground

mill are:

1. The mandrel must be level.

2. Log-carriage track must be at right angles

to the mandrel, leveled so that the tops of carriage bunks are horizontal, and so bedded that

carriage headblocks clear the saw by y^ to %

inch at a line approximately 1 inch above the

saw collar,

3. Track and husk must be well bedded and

bolted in order to remain truly alined under the

shocks and stresses of sawing.

The procedure of setting up a ground mill begins by marking on the ground the outline of

sills and saw pit. Sills are bedded firmly in the

ground to about one-half their depth. The sills

must be solidly supported their entire length,

with the ends under the outside track, each

resting on a post bedded solidly in the ground.

Earth is tamped firmly against the sides. A saw

pit is dug that will be ample to provide for the

type of dust removal and feed works employed.

The husk is placed at the desired location

with a sill under each end, to which it is accurately bolted. Sills should extend parallel

from beyond the outside track to the pulley end

of the mandrel. Sills should be at least 10 by 10

inches in size and made of well-dried heartwood

of durable species. Mills differ as to methods of

locking the husk to the sills. In some, metal

plates or angle irons are used; in others, the

husk is bolted directly to the sills. Husk and

sills should remain rigidly fixed under the

heavy stresses of operation ; mortising of plates

into sills and dressing the sill face where it contacts the husk contribute to stability.

After the husk is firmly bolted to the sills,

the mandrel and feed works are set in place.

Portable mills are usually provided with light

metal carriage tracks fastened to light wood

stringers, and correct track width is maintained

by cross pieces between the stringers. These

stringers rest on ties, which in turn may rest

on sills bedded in the earth. The gap in the silltie foundation at the saw pit should be reinforced with 6- by 8-inch cross pieces saddled

between the husk sills directly under each

track. Good foundations for the track beyond

the saw pit are assured by bedding under each

rail a 4- by 6-inch sill leveled with the top of

the husk sills.

The mill manufacturer patterns the drum

shaft and track stringers to insure that the

headblocks clear the saw by i/^ to % inch at a

line about 1 inch above the saw collar. In some

mills this 1/2- to %-inch clearance is fixed by

metal plates between husk and track. Lacking

these, two blocks are fitted between the husk

and rail stringer, one being bolted to each sill.

The track stringers are bolted tightly to the

husk sills and ties, and the track is checked to

make certain that it is at absolutely right

angles to the mandrel and level both ways

throughout its length. Other track sections are

then laid and leveled.

Next, the carriage is placed on the track and

run its full length, and the accuracy of leveling

is checked with a level lengthwise and across

the bolster tops. If inaccuracies occur, they are

corrected by raising or lowering the sills under

the ties.
74 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

o-ac3

73

3

o

M

.a-M

o

0)

â

f

l
SMALL SAWMILL OPERATOR'S MANUAL 75

One end of the cable is fastened to the cable

eye on the front of the carriage, and the cable

is run through the deck-end pulley and back

over the drum. Usually the first strand is car-

;;; ried over the top of the drum and wrapped

}; three to five times around it, leaving the drum

;v at the top. These wrappings should occupy the

mid-portion of the drum. Then the cable is

, threaded through the other pulley and fastened

to the eye at the rear of the carriage. The cable

should be tight when fastened.

Mills worn by long service may give poor performance even when carefully set up. For this

reason, mandrel bearings, carriage wheels, set-

' works, and headblocks should be checked. The

mandrel should run level and without end play,

which calls for good bearings. The same is true

of carriage wheels on the guide rail. Provision

.:' is usually made for taking up play developing

J in the carriage wheels. They should be kept adjusted just short of binding or sticking. Worn

setworks parts prevent accurate cutting, as do

worn bolsters on headblocks.

With the guide blocks fastened to the husk

the next step is to hang the saw. It must fit the

' mandrel perfectly, neither so tightly that it

must be forced on nor so loosely that there is

perceptible play. Place the loose collar and

tighten the nut hard against the collar. Check

with a plumb line to make sure that the saw is

vertical and not seriously dished. Minor dishing

• can be corrected by inserting paper shims. This

is done by cutting two paper rings, one with a

rim one-half inch wide and of the full diameter

of the collar, the other with a rim one-half inch

wide and of a diameter to fit inside the hole in

the first; ordinary kraft wrapping paper is

suitable. Both paper rings are oiled, and the

larger one is put on the fast collar and the

smaller on the loose collar if the saw dishes

away from the log ; if it dishes toward the log,

the two rings are reversed. Additional rings

may be used if required. The operator should be

on guard against reversing the dish.

The next step is to put the lead in the saw.

. This is done by slewing the mandrel slightly in

a horizontal plane by means of set screws controlling this adjustment, so as to bring the

front edge of the saw slightly into the log. Be

sure the mandrel does not bind in the bearings

after adjustment. Try a l/g-inch lead in 20 feet.

If the saw heats at the rim reduce this; if it

heats at the center, increase the lead. A simple

means of getting a 1/8-inch lead in 20 feet is

to bring the carriage up so that the rear bolster

' is opposite the saw center; then fasten a strip

. along the top of the bolster to project within

Vs inch of the saw. Run the carriage 20 feet

. away from the saw center toward the deck, and

stretch a line from the end of the strip across

the face of the saw. Adjust the mandrel until

the string, drawn taut, touches both edges of

the saw along the log-side face. Set the boardside guide pin to the saw in the new position

and, when the saw is running, set the log-side

pin close enough to steady but not bind the saw.

Attach the spreader wheel behind the saw to

clear the teeth about 1/2 inch and in the same

plane as the saw, but not so that it rubs the log.

The guide blocks should be adjusted so that

the guide pins clear the bit holders and touch

the saw about l^ inch outside them and 2

inches below the level of the carriage bolsters

on the front edge of the saw. After placing the

correct lead in the saw, the board-side pin

should be set to leave a gap about 1/50 inch to

the saw plate. The log-side pin is set to provide

a like gap after the saw is brought up to operating speed.

There remains the installation of log deck,

power unit, and possibly lumber rolls, edger,

cut-off saw, dust conveyor, dip tanks, shelter,

and yards. A simple log deck can consist of

skids to facilitate easy approach of log to the

carriage and spaced as in figure 99. A gentle

downslope to the carriage is helpful but not

essential.

The power unit, if hooked up by means of a

flat-belt drive, should be so placed that the

driver wheel and driven wheel are about 25 feet

apart, their mandrels truly parallel and the

pulleys in line, the belt centering on the pulleys.

Guides are not used to keep the belt centered.

Units are spaced so that the belt has about a

3-inch sag on the slack, or top, side. Place the

belt rider on top of the slack belt. For an edger

that is driven from the headsaw mandrel, the

lower belt is slack, the rider being on the under

side of the lower belt and close to the small

driven pulley on the edger.

Building Plan and Machine Location for

Sheltered Portable Mill

According to Plan 2

With a cut of 200,000 to 1,000,000 board feet

at one site, the operator often will erect a simple shelter. The equipment is usually on the

ground or on a floor at ground level. Housing a

mill of this size in a simple shelter according

to plan 2 (fig. 100) will insure more sawing

days, fewer delays, greater comfort to workmen, and longer life of equipment. The plan applies to either tractor-driven or steam-powered

mills.

Plan 2 differs from plan 1 chiefly in that a

shelter is provided for the machinery. This

shed (fig. 100) requires about 4,000 board feet

of lumber, exclusive of trestle, and 1,650 square

feet of corrugated roofing. If wood is substi-
76 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

I

1

V-.o-M

H

I^

T

-

1

-1

\\

p=

-O-t .

1

1

B

M& 1

—< h

1

-

1

C fSh

O II

¿7' 1

2 -^1 °T4'{H>"

—( <S 1

o ,-- (Ü)

•Ci [" *o

( ) r ' '^

__ § ( )

SJ

—( y ïl _.

« "

Q n !q!

-T- •*,-<>.

. Lr

•o

'

-; <t

v> I-!- S ~ ( )

k

Í

( )

tl=

e ! i

_ s

>î i^^ *^ ^

/¡J â

5:

o

P<

S

.r

H
SMALL SAWMILL OPERATOR'S MANUAL 77

tuted for corrugated roofing, a higher pitch and

some 2,000 board feet more lumber will be

needed.

In this layout, slabs passing over dead rolls

are loaded on a small car, together with edgings, are run out about 75 feet from the mill

and dumped so as to slide 20 feet down five inclined rails to the fire. Lumber loaded on another car is run out to piles over a separate

track. The columns supporting the trestles are

placed in pairs at 8-foot intervals and are joined

with 2- by 6-inch caps.

Where rolls are installed, the top of the roll

should be level with the bed of the edger. The

simplest means is to lower the ñoor supporting

the edger; otherwise, the husk and track must

be elevated so that the tops of the carriage bolsters are level with the edger table.

In the event that a relatively small portion of

the material goes through the edger, the rolls

are omitted and the lumber car brought within

6 feet of the headsaw, in line, so that sawed

boards and slabs fall to the car, the slabs being

carried across the carriage tracks and loaded on

a slab car outside the mill. The floor of the slab

car is supported by a single beam lengthwise

along the middle. The beam has beveled ends

resting in notches, so that it pivots as the load

is dumped. One end of a chain is permanently

fastened to the car floor and the other temporarily to the truck body to prevent accidental

pivoting. A comparable slab car is shown in

figure 101.

In plan 2, the 4- by 6-inch joists supporting

the mill floor are spaced about 3 feet apart, but

care should be taken to have a joist directly

under the breaks in the carriage track. It is

advisable to provide for a roomy sawdust pit

under the headsaw (at least 3 Va feet from the

saw rim to the bottom of the pit) and one under

the edger large enough (6 feet deep by 4 feet

wide) to permit a wheelbarrow to catch sawdust directly. For steam-powered mills, the engine would be mounted in the space labeled

"tractor" and the boiler set up so that it is conveniently near the slabs at the rear of the mill.

Building Plan and Machine Location for

Semipermanent Tie Mill

According to Plan 3

With a prospective cut of more than 1,000,-

000 board feet, a reasonably permanent building and other facilities are justified. Such mills

are equipped to produce between 1,000 and

2,000 board feet per hour with a minimum of

labor. For capacities in this range, the layout of

a tie mill is shown in plan 3 (fig. 102), and that

of a lumber mill in plan 4 (fig. 103).

A plan for a building with sides and ends

boarded up but unfloored is presented in plan

3 for a semipermanent tie mill. It requires approximately 10,000 board feet of lumber. A

rather large crew is needed, consisting of two

deckers, one setter, one sawyer, one tail sawyer,

one tail edger-slab oif-bearer, one trim-saw

M-80926-F

FIGURE 101.—Slab car. Bed pivots on two hinges attached to longitudinal beam near middle of car.

471449°—58 6
78 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

—.8 -1

00

,8''„t''„t'

\
SMALL SAWMILL OPERATOR'S MANUAL 79

operator, one pile-out man, one bark-peelerclincher, one truck-mounted derrick operator,

and two lumber-tie stackers. Production for a

9-hour shift is 450 ties and 3,600 board feet of

side lumber. The headsaw motor has a rating of

100 horsepower, that for the edger 25 horsepower, and that for the cut-off saw 8 horsepower.

Logs can be delivered directly to the deck or

dumped in the log yard as reserves.

Slabs and edgings are pushed down the inclined rails and drop outside the mill onto two

skids. A truck equipped with a derrick slings

a bundle of this refuse on a chain and hauls it

to a nearby pile for conversion to fuel wood ; or

slabs may be thus disposed of and edgings

bundled and tied by the trim-saw operator. Ties

and boards go out the rear of the mill, the ties

to the tie dock and the boards onto skids to be

picked up by the derrick-truck and hauled to

the pile.

The convenient device shown in the plan

(fig. 102, D) for measuring standard tie lengths

at the cut-off saw consists of infeed rolls 2

inches in diameter, spaced 4 inches center to

center, a central dead spot 3 feet long with the

spiked device for holding the tie while it is

being cross cut, then a section of rolls. Rolls

are equipped with ball bearings. The marker

operates just before the tie reaches the cut-off

saw. It is free to rotate, forcing the stop down

as the incoming material reaches it, but the

counterweight brings the plate up between the

rolls when the tie has cleared. The trim-saw

operator pushes the tie back until the end engages the plate. To operate the marker beyond

the cut-off saw, the operator steps on the pedal,

thus raising the plate across the line of travel.

With the same motion, the spikes in the member under the saw table are raised and, as the

pedal is pushed completely down, the spikes are

raised above the table top to engage the tie.

They are located about 8 inches from the guide

rail, which is across the rolls from the operator

(fig. 102). .: ^ :;,, : r v.,

Building Plan and Machine Location for

Semipermanent Lumber Mill

According to Plan 4 ^

The semipermanent mill shown in figure 103

is supported at least 4 feet off the ground by a

series of piers. These are spaced 6 feet apart

along the length of the mill and 8 feet apart

across the mill, except that those in the five

series at the front of the mill up to the saw are

spaced 4 feet apart. The plank ñoor is continuous, except that the power-unit base rests on

the ground and the space over the unit and

drive belt and extending to the log haul-up

mechanism is unfloored and may serve as a

saw-filing space. The track and husk are raised

so that the tops of the carriage bunks are level

with the edger bed. Approximately 11,000

board feet of sawed material are required, together with 2,500 board feet of piers and 2,400

square feet of roofing.

A blower delivers sawdust from the headsaw

and edger. A conveyor belt delivers slabs and

edgings, to the refuse chain at the rear of the

mill and thence to the burner, placed at least

75 feet from the mill. The lumber, after passing

through the gravity dip tank, is piled for transportation to the yard or elsewhere.

The crew consists of at least seven men : One

man to haul up logs, a deck man, a sawyer, a

tail sawyer, a tail edgerman, a trim-saw operator, and a pile-out man. The equivalent of a 100-

horsepower Diesel engine should be used for

power.

Figure 103 is drawn to scale. Pulley sizes are

based on the assumption that the drive pulley

to the headsaw has a diameter of 17V2 inches

and that to the intermediate shaft 20 inches,

each turning at 1,000 revolutions a minute. The

suggested speeds for various pieces of equipment are: Headsaw, 650 revolutions a minute;

log haul, 100 lineal feet a minute; edger saws,

2,000 revolutions a minute; blower, 2,800

revolutions a minute; trim saws, 1,720 revolutions a minute; and slab-conveyor belt and refuse chain, 200 lineal feet a minute.

The drive shaft on the power unit is 314

inches in diameter, the intermediate shaft is 3

inches, the blower shaft 1-7/8 inches, and the

trim saw shaft and conveyors are 2 inches in

diameter.

Widths of the various drive belts should be as

follows: To the headsaw, at least 12 inches

wide; to the intermediate shaft, 10 inches;

from the intermediate shaft to the trim-saw

shaft, 8 inches ; from the trim-saw shaft to the

drive pulley, 6 inches; from the intermediate

shaft to the second intermediate and all belts

beyond for conveyor transmission, 6 inches;

from the intermediate shaft to the edger, 8

inches ; and from the intermediate shaft to the

blower, 5 inches. The belt conveying slabs is 15

inches wide. The lugs in the trash-conveyor

chain are spaced 8 feet apart.

Building Plan and Machine Location for

Permanent Heavy Mill

According to Plan 5

A plan-for a heavy type of small but permanent Douglas-fir mill is given in figure 104.

This mill, producing from 3,000 to 5,000 board
80 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

feet per hour from logs with a diameter inside

bark of between 20 and 40 inches, is a "small"

mill only on the west coast. Production is predominantly of stock at least 2 inches thick and

includes timbers sold green from the mill. The

mill building requires about 55,000 board feet

of timbers and lumber and 1,400 lineal feet of

piling.

Substituting a band headsaw would require

no change in layout if timbers and ties are not

to be cut. If timbers and ties are cut, substitution of a band headsaw would require a swing

cut-off and docks.

The list of materials needed for building and

equipping this permanent heavy mill includes:

1 gas drag saw for the pond.

1 10-horsepower electric motor, with gears, shaft,

and chain, for the log slip.

1 10-horsepower electric motor, with winch and

chain, for the overhead log turner.

FIGURE 103.—Plan for
SMALL SAWMILL OPERATOR'S MANUAL 81

1 lO-horsepower electric motor for the carriage setworks.

1 200-horsepower electric motor for the headsaws.

1 7%-horsepower electric motor for the live rolls.

1 100-horsepower electric motor for the edger.

1 20-horsepower electric motor for the refuse chain

to the burner.

1 15-horsepower electric motor for the lumber conveyor chain.

1 15-horsepower electric motor for the trim saws.

1 5-horsepower electric motor for the burner blower.

1 carriage, 7 by 20 feet, to include three headblocks;

two knees; a screw shaft; drop dogs on a perforated movable-arc post; motor-driven friction wheels

to activate the setworks; and a feed friction-bullwheel, cable driven.

1 husk, carpenter built, supporting a 7-gage, 60-inch

headsaw and a 7-gage, 60-inch topsaw, with 42

insert-type. No. 4 style teeth per saw.

1 set of 20-inch live rolls.

1 72-inch, four-saw edger.

1 set of transfer chains with live rolls to the edger

bed.

IT

4^=1^ 4M"

DIP TñNK

TRIMMER

yZSOOR.PM. 3

'¡rizoo R.P.M-

,_.:^ZZ7 R.P.M.

'"'=p 60 RPM.-)

6S0R.P.M'

BELT-ZOOLF.PM.

,~,..........^

semipermanent lumber mill-
82 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

1 refuse chain from the headsaw to the rear of the

mill.

1 refuse chain from the rear of the mill- to the

burner 100 feet distant.

1 set of lumber conveyor chain (70-foot table).

1 set of trim saws (four). ,.

1 blower for the burner. f '

1 burner.

1 pond 200 by 250 feet in area by 5 feet deep.

The crew consists of two pond men, one

operating the drag saw and the other feeding

logs to the slip ; one decker operating the pullup, rolling logs and helping turn them; one

setter-dogger; one sawyer; one tail sawyer;

two edgermen; one trim-saw operator; four

sorters ; one boss ; one night watchman ; and one

filer-mechanic, making a total of 16 men. This

excludes the load-out force in mills loading directly from dock to railroad car.

FIGURE 104.—Plan for permanent lumber mill, heavy type.
SMALL SAWMILL OPERATOR'S MANUAL 83

LOAD-OUT EQUIPMENT

Several methods permit orderly handing of

lumber at the rear of the small sawmill. Depending upon production volume, one or another

of these methods appears well suited to various

types of small mills.

Car and Trackway

One means of handling of lumber at the rear

of the mill is to load it on a car and transport

it over a trackway to piles along each side (fig.

105). Trackways are level or with a down slope

toward the yard of up to 1 foot in a run of 50.

By making the car frame detachable from the

axles, several cars can be used on one track, the

empty car being brought from the yard and set

off the track to give right-of-way to the one being loaded.

PROP in PLACE

4-0 -

1

^\^¿\í,'

K. 1 . . \ \

K

-|--_tr -|-

xNwVé'

E 3

lr^¿ ll4 \^S^ ;

;W7' 1

swt view OP PROP BND VIEW OF PROP

2'x4--~

i'xiCxa'-o'

!'x 2" MILFIGURE 105.—Car and trackway for transporting

lumber from mill to pile.

Lumber Props

Mills built directly on the ground can use the

lumber-prop method (fig. 106), which permits

grouping of items by species, thickness, width,

length, or grade at the mill instead of at the

pile. A series of rolls carries the lumber out the

FIGURE 106.—Lumber-prop load-out device.

rear of the mill, and one man piles it, by required items, on special props. Spacing between

props should be adequate to permit backing the

wagon, truck, or bummer under the load; the

prop is just high enough so that the vehicle's

bunk contacts the load about an inch ahead of

the prop, the prop itself being placed about onethird the length of the load from the front end.

About 500 board feet makes a load.

The bummer or other two-wheeled vehicle is

backed under the load so as to engage it just

ahead of the prop. The load is chained to the

bunk and, with the driver standing on the front

end to minimize drag, the bummer is started,

causing the prop to fall forward. The back of

the load drags on the ground. One man driving

a single horse can usually move production

from mill to pile where the yard is within a

quarter mile of the mill. .;

Rolls

For mills built off the ground, a simple yet effective method of handling loads of up to 1,000

board feet utilizes an inclined platform and

rollers (fig. 107). The platform's inchne from

mill to truck is IV2 inches in 10 feet, with the

rear about 2 inches above the truck bed. Three

wood rollers, each 6 inches in diameter and 7

feet long, are blocked on the skids 5 feet apart.

If separations are required, the platform is

made wider so as to carry several loads at a

time, each provided with a set of rollers.
84 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

FIGURE 107- -Inclined platform and rolls for loading

out lumber.

To transfer the load to the truck, the vehicle

is placed opposite the load so that the longest

boards will clear the platform when the lumber

has been shifted to the truck. A 4- by 6-inch by

7-foot timber is placed with 6-inch face downward on the truck bed about a foot from its

rear. A 6-inch roller is placed just ahead on the

truck bed, the blocks are taken from under the

rollers supporting the load, and gravity moves

the load onto the truck. As it engages the roller

on the truck, and before the rear of the load

drops off the platform, the 4- by 6-inch timber

is turned with a 4-inch face against the truck

bed to minimize the shock of the drop.

Loading Scaffolds

Variations of devices to support loads clear

of the ground, so that a vehicle can be backed

under and the load picked up as a unit (figs.

108 and 109) are suitable for mills built off the

ground.

The type shown in figure 108 is used for loads

of about 1,000 board feet moved by a truck or

wagon relatively short distances to the yard.

No grouping is usually made at the mill, other

than some sorting of like items within the load.

Usually two men transport and pile the production directly from the vehicle. Supports a are

hinged. The ground line of the roadbed is so inclined that, in backing between supports a, the

rear end of the truck bed—or, if bunks are

used, the rear bunk—engages the load of lumber just ahead of support b. As the truck continues to back, the load is lifted clear of support

¿), and supports a fall back, pivoting on the

hinges. If a truck bed is used, cross members

must be placed so as to support the load more

than 6 inches oif the bed, to allow support c to

be taken from under the load. The distance between supports a and b will depend upon the

truck bed length or distance between bunks.

The length to which the lumber extends beyond

support c is regulated to clear the cab. The

width of the pile is that readily taken on the

truck.

The type shown in figure 109 is used for

truck-trailer loads of 4,000 board feet and relatively long hauls. The load is supported just

high enough to clear the bolsters as the trailer

and trucks are backed under it. The driveway is

planked under the load, and with enough incline so that the trailer bunk engages the load

at the moment the bunk of the truck is behind

support a. The jack is placed on support b and

one end of support a is lifted, the blocks removed, and the end of the support lowered until

it rests on the post. The jack is taken to the

other end of support a, and the process repeated

until the support can be removed. The load is

chained to the vehicle and is then ready to

move. The specifications in figure 109 are for

bunks 8 feet wide on dual-drive, dual-wheel

trailers.

Sliding Skids

The specifications for sliding skids shown in

figure 110, A are for truck-trailer loads of 4,000

board feet and relatively long hauls. The lumber is piled across skids a to a load width suited

FIG. 3

LOADING SCAFFOLD FOR IM BD. FT.

FIGURE 108.—Hinged-post loading scaffold. Truck is backed between hinged supports a, lifting load off support h.

Supports a fold back and support c is removed.
SMALL SAWMILL OPERATOR'S MANUAL 85

FIGURE 109.—Jack-lowered lumber scaflfold. Support a is raised by jack on support h, one end at a time, blocks

under support a are removed, and it is lowered to posts so that load rests on truck bunk backed underneath.

to the bunks of the carrier, as indicated by

angle-iron guides b. Loading and unloading are

facilitated if truck and trailer bunks are provided with 4-inch channel-iron bolsters with

rollers inset to clear the bolster by about 1/2

inch (fig. 110,5).

To move the load, a cable from a hand winch

anchored bunk-high across the truck road is

connected to chains c (fig. 110, A) and, when

operated, pulls the loaded skids over the rolls.

The truck is placed so that the skids will be

ahead of the bolsters rather than opposite them

and the skids are removed when the load is

placed on the bolsters. If a truck with a solid

bed is used, the skids are pulled directly onto

the truck bed and remain under the load. The

truök driver or helper operates the hand winch.

If the skidway is lengthened, several loads

-CHANNCL IRON BÛLSTBUS

B

FIGURE 110.—Loading devices using sliding skids. A, Platform showing skids a, angle-iron guides 6, and chains c.

B, Truck, showing channel-iron bolsters and rollers.
86 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

can be stored against irregularities of truck

schedules.

At the delivery point, unloading consists in

placing a heavy chain around the load and pulling it laterally on the skids with a power device,

or lifting it with an overhead crane.

Trucks and Rails

A method of loading out suited to heavy loads

requires two firmly fixed sections of railroad

rails, each of a length equal to the over-all load

width (7 feet) across the truck frame (fig. Ill,

A). One rail is about 30 inches behind the rear

axle of the truck and the other about 7 feet

ahead of this rail. Kiln trucks with a welded extension (fig. Ill, ß and C) can be placed on rails

at the back of the mill, spaced exactly as the

rails on the truck (fig. Ill, A). The truck is

spotted so that its rails are an extension of

those from the mill, with not over a 3-inch gap.

A jack is used under the end of each rail nearest

the mill to bring to and hold the truck rails at

the same level as those of the mill. A winch and

cable are used to pull the load onto the truck.

At the unloading point, rails are provided with

the proper spacing to permit running the kiln

trucks with the lumber off the hauling truck,

using jacks and winch as outlined.

Several variants of this method are used

normally for loads of 4,000 or 5,000 board feet

of stock, mainly 16 feet in length. Jacks housed

in portable standards can be used either to ease

the load onto the truck or to take it off (fig.

112). A set of two jacks supports a small log or

metal beam at a height adequate for bunk clearance as the truck is backed under it. The roadbed is inclined downward at the front of the

load so that, in backing between the supporting jacks, the rear bunk engages the load and

WCLDBD CONSTRUCTION

7'

FIGURE 111.—Kiln-car method of loading lumber. A, Truck with rails on bunks; B, kiln car on rails of load-out

^,; platform; C, details of skid. .
SMALL SAWMILL OPERATOR'S MANUAL 87

positions it properly with relation to the cab

and bunks. The truck is stopped at this point,

the front support is jacked down, and the load

is settled on the truck without shock. Where

this equipment is used to remove a load from

the truck, four jacks are used, two elevating

the front support and two the rear one.

In a lever-arm support, the end of the log

cross piece is supported by the end of a plank

which can be used as a lever to raise or lower

the cross piece slightly (fig. 113). To load, the

truck is positioned as with portable jacks, the

key bolt at a (fig. 113) is removed, and restraining force is apphed to the plank to steady

the descent of the front corner as the plank

pivots under the weight of the load. The stop at

b is about 5 feet above pin a. The let-down of

the front corner resulting from the plank end

traveling from a to 6 is not enough to bring the

load down onto the bunks, but after the other

front corner is lowered in a similar manner, the

supporting log can be easily turned down with

a cant hook toward the front end of the load

until the load rests on the bunks.

In another variant, a rectangular frame (fig.

114) adequate to support one end of the load

at the required height is placed about 10 feet

from the mill platform. It may be tilted with

the top slightly toward the mill, and propped

with a plank, or it may be supported by a notched 2 by 4 (fig. 114, A) with the other end of the

2 by 4 nailed to the load-out platform ; or it may

be tilted with the top slightly ahead of center

and supported by a small chain (fig. 114, ß). It

may be set up directly on the roadbed (fig. 114,

A) or be anchored and turned on a pipe (fig.

114, B) or hinge. If it is anchored, a portion of

the planked roadbed is cut out so that the frame

is countersunk when flat, to provide a roadbed

for the truck wheels at the same level as the

adjoining roadbed. The height of the gate

should be adequate to keep the front end of the

pile above the end on the load-out platform, so

that the truck roller engages the load about a

foot back from the front of the load and lifts

the load off the support as the truck continues

to back under the load. The mill platform has

a step to provide a backstop as the truck continues back in placing the load.

m

PLATFORM

B

1^

30"

a

3^'D/ÂM£TER

^^r^METAL BA5E-

\^50UARE FACE.

FOR WRENCH

WB

4"X (}"3TRUT5-

-2"X è" ßRACEI2-X-J2" ' : ' -í^r V ^- ^4-X-6"ß/}5E -

D

FIGURE 112.—Portable jack supports used for loading out. A, End view; B, side view; C and D, end and side

views of support.
88 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

a

-I

• I

I I

I I

LOAD

^'BOLT

L..I

FIGURE 113.—Lever-arm support for load. Left, front view; right, side view. Bolt o, when removed, causes

plank to pivot upward to bolt 6, thus lowering opposite end of load. Removal of log brings end of load to truck

bunks.

V 2X4 8fíAC¿

\C01L/IK

y BC/IRING

MCTAL

APRONIfUflDE

f-r—-)-—3-f—i^_

5PAC/N6 or KOLLERi

c

FIGURE 114.—Details of two types of gate frames. A,

Gate frame supported by notched 2 by 4; iî, gate

frame supported by chain and hinged on a pipe;

C, truck equipped with rollers for ease in loading and

unloading, with details of truck roller and roller

spacing.

M-83667-F

FIGURE 115.—Stacking lumber in unit packages by

means of tram car running from rear of mill.

Figure 114, C indicates the truck features

and roller spacing. The metal apron at the rear

minimizes breakage as loads are rolled off the

truck. By cutting the end of the rear roller to

take a wrench, provision can be made to unload

the entire package in one operation.
SMALL SAWMILL OPERATOR'S MANUAL 89

Fork-Lift Trucks

Lumber can be taken from the rear end of a

mill with fork-lift trucks. The lumber must be

assembled in units that can be handled and carried by the forks, and the unit must be placed

so that the forks can be inserted beneath the

load. The lumber can be handled in bulk-piled

units or in sticker-piled packages prepared for

seasoning in the yard. The bulk packages can be

taken to the yard or loaded onto motor trucks

for shipping in the green condition. The same

fork-lift truck used to take lumber from the

rear end of the mill can be used in log yarding,

and various miscellaneous handling and transporting operations.

Where stickered packages are picked up,

space for stacking bays should be provided. An

arrangement consisting of a tram car running

on a track can be used (fig. 115). The lumber is

unloaded directly from the tram car to stickered

packages placed on bolsters.

MILL OPERATION

The most advantageous method of sawing

logs on any operation depends upon market demands and price difference between different

grades and between thicknesses within a grade.

Thick stock of the better grades normally

brings a better price than inch lumber. In hardwoods (graded from the poor face) the likelih'ood that the grade on the inside face will hold

up to that on the outside decreases as thickness

increases ; hence, to capitalize on thick stock requires expert knowledge by the sawyer. Thicknesses most commonly produced by small mills

are shown for several hardwood species in

table 14.

TABLE 14.—Thickness of hardwood stock of

various species commonly produced on small

sawmills

Species

Thickness in inches

4/4 5/4 6/4 8/4 10/4 12/4

Ash X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

Basswood _ - X X

X

X

Beech

Birch, yellow- X

Cherry, black

Cottonwood - X X

Elm X

X

X

X

Maple, soft

Maple, sugar _ _ X

X

X

X

X

Oak, black

Oak, chestnut

Oak, upland red ' _ X

Oak, lowland red '

Oak, upland white '

X

X

X

Oak, lowland white '

Yellow-poplar. . X

1 Includes all commercial species.

The sawyer must know the following details

of lumber grading: (1) The minimum width

and length provisions of each grade, to guide

himself when slabbing; (2) the defect allowance or clear-face requirements of the grade,

as a guide in log turning; and (3) the grade

provisions applying to the lowest merchantable

grade, in order to avoid wasting time or making

unmerchantable stock.

The edgerman must know (1) the minimum

width-length provisions of each grade; (2) the

amount of permissible wane; and (3) the provisions covering standards of manufacture, particularly that applying to crook.

Both the sawyer and edgerman should note

that minimum thickness, width, and length

provisions of the grade rules usually apply to

dry lumber and must allow for shrinkage in

thickness and width. Hardwoods are edged to

give the widest possible board in any fraction

of inches above the minimum required. Softwoods are sized to give widths in inch or 2-inch

intervals.

Recommendations applicable to milling both

softwood and hardwood logs are:

1. Clear faces should be taper sawed in order

to get the maximum possible footage in upper

grades.

2. Thin stock should be taken next to the

slab to minimize edging waste.

3. The pith should be enclosed within a

boxed-heart item where splits and checks arc

not considered a degrade. , ,

Milling Softwood Logs

The major markets of small mills cutting

softwood lumber are those taking standard retail-yard items, box lumber, and railroad ties.

Production, except in the Douglas-fir region, is

rarely geared to the special size and finance requirements of industrial, export, and bill-timber (large-sized timbers) markets. To minimize

waste, products of different sizes should be

made, the particular sizes being varied according to the log. In this way complete utilization

is most nearly attained. It is also desirable to

saw the log in such a way as to produce lumber

of maximum grade values.
90 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

The size and grade standards for merchantable items are given in grading rules sponsored

by lumbermen's associations, and a sawyer

should master these provisions for the species

sawed. Normally, however, there is a greater

demand for certain sizes or grades than for

others. The effect of this is to limit the size

combination that can be used. For instance, the

nominal widths specified under softwood rules

include each inch class from 3 to 12 inches, but

a market rarely exists for widths of 7, 9, and

11 inches. Likewise, for some softwood species.

No. 1 Common boards are in little demand,

whereas No. 1 Common dimension is readily

sold. Since softwood is graded from the best

face, usually the sawyer can estimate the approximate grade before setting is done and

readily substitute dimension for boards.

The several methods of sawing softwood logs

differ mainly in the sequence used in turning.

The two objectives of a sawyer are to recover

maximum grade values and get maximum

volume production per hour. It is not possible

to get both by any one method : either the frequent turning required to recover the maximum grade values reduces volume, or the minimum turning necessary to get maximum production sacrifices grades. In order to get a

balance between grade values and production

volume, turning procedure must be varied in

accordance with log qualities, sizes, and mill

facilities. No rigid set of instructions can be

universally applied. The ones suggested are

commonly used and provide the beginner with

a definite starting point.

The turning sequence is easily identified by

terming the first log face to be sawed, face 1,

after which faces 2, 3, and 4 will be turned in

a sequence starting from the top and ending

with the bottom, face 3 being opposite face 1.

Greater production volumes are possible by using the 1-3 sequence; better grades usually

result from some combination of 1-2-3-4.

In sawing logs, the sequence in which faces

can be sawed is limited by the requirement that

adjoining sawed faces must be at right angles.

To insure this, the first face sawed must be

turned to the bolsters or to the knees. On mills

equipped with dogs incapable of preventing the

log from turning while face 1 is sawed, a slab

is taken from face 4 and the log turned so that

face 4 rests on the bolsters. In the following instructions it is assumed that the dogs will hold

the log firmly; otherwise, the outlined procedure must be changed so that face 4 is slabbed and turned to the bolsters before face 1 is

worked.

For logs 12 inches or less in diameter and

promising only common grades, the 1-3 sequence is used, sawing nearly to the center

from face 1 and then turning the log 180° and

finishing it. The dog board is usually cut to

dimension size. If the first face is not worked

to near the center of the log, most types of dogs

will fail to hold the piece as the opposite face is

worked beyond the center.

The first slab should give a face of a minimum merchantable width. In slabbing the opposite face, the sawyer adds the thicknesses

and saw kerfs remaining to be cut and so slabs

the piece as to end up with a dog board (the

final board) of proper size. In practice the second face to be cut is brought to the saw line to

give a tentative face of minimum width, and

the sawyer then decides whether a thicker slab

is required in order to have a dog board of

proper size at the finish.

For logs of common-grade quality exceeding

12 inches in diameter, the 1-3 sequence has disadvantages. The edgerman is prone to lose potential footage in the wide center boards

through improper ripping. Lumber from rip

lines along or near the pith tends to crook in

drying. For such logs, a 1-2-3 sequence ig

recommended if turning is done with cant

hooks, or a 1-3-2-4 sequence if powered equipment is used that turns the log up and over. In

using the 1-2-3 sequence, faces 1 and 2 are

slabbed to give boards of minimum width, and

face 3 to end with a dog board of proper size.

In the 1-3-2-4 sequence, face 1 is slabbed to

give boards of minimum width, face 3 to end

with a cant thickness of 6, 8, 10, or 12 inches

instead of a dog board, face 2 to give a face of

minimum width, and face 4 to give a dog board

of proper size as sawing is completed.

A secondary refinement in sawing of common

grades is that knots should be toward the center and away from the edges of sawed stock.

Thus, insofar as is possible, the log should be

placed on the carriage so that the visible knots

will be toward the center of the face rather

than at the margin.

The recommended practice for logs promising

a portion of their lumber in grades above common is to place the high-grade faces to the saw

and taper-saw them (parallel to the bark). If

all but one of the faces is clear, the log is placed

with the poor face to the saw, slabbed, and

turned to face 2 on mills employing turn-down

equipment. Before face 2 is sawed, the small

end of the log is set out to get a slabbed face of

uniform width the length of the log. After slabbing to a face of minimum width, this face is

sawed until the grade drops to common.

The log is next turned to bring face 3 to the

saw, which is slabbed and sawed as was face 2.

By slabbing face 1 as instructed, face 3 will be

taper-sawed without setting out the small end.

Next the log is turned to face 4, the small end
SMALL SAWMILL OPERATOR'S MANUAL 91

set out as for face 2, and this face is sawed until common lumber develops. Before turning to

another face the taper is taken out by retracting the taper blocks, bringing the cant against

the knees, and sawing the wedge so as to have

a cant thickness of 6, 8, 10, or 12 inches. If

short pieces are merchantable, one or more

short boards are taken in straightening the

cant. In order to end up with a dog board of

proper size, the sawyer adds the thicknesses

and saw kerfs remaining to be cut and slabs

accordingly on the third and fourth faces of the

log.

If two adjoining faces are clear, the log is

placed so that one poor face is to the saw and

the other is up. Face 1 is slabbed and may be

sawed lightly, then face 2 is brought to the saw

and treated likewise. Faces 3 and 4 are successively taper-sawed deeply without use of

taper blocks.

If two opposite faces are clear, the log is

placed with a clear face on top. After face 1 is

worked as described above, face 2 is brought to

the saw, the small end of the log is set out, and

this face is worked until common lumber develops. Next, face 3 is sawed as described for

face 1. Face 4 is taper-sawed after the small

end is set out, and before the cant is turned to

another face it is straightened as previously

described.

A log with a single clear face is placed on the

carriage with this face against the knees, thus

permitting this face to be taper-sawed without

use of taper blocks. These instructions are for

mills employing equipment which turns down

logs. For mills turning up, the log is turned

either 180° or 270° after face 1 is worked and

the procedure modified to conform to this different turning system. Small mills deriving no

premium from upper grades "saw around"

large logs as described, except that the small

end is not set out.

Rough softwood lumber that is later to be

surfaced, or surfaced and patterned, must be

edged and trimmed to widths and lengths that

allow for the manufacture of finished lumber of

definite size standards. Usually nominal widths

are 3, 4, 5, 6, 8, 10, and 12 inches with evenfoot lengths. A flitch that can be edged and

trimmed to produce a board of 9-inch nominal

width and 11-foot length, but cannot be made

10 inches wide by 12 feet long, should normally

be sized to 8-inch nominal width and 10-foot

length. Since wane is excluded from surfaced or

patterned material for most items, edging and

trimming should remove wane that will not be

surfaced out.

A simple rule to guide the edgerman is that

normally material should be edged to get the

widest merchantable stock possible and in the

maximum even-foot length, but that the width

should be reduced by 2 inches wherever 4 feet

or more can be gained in length. The edgerman

thus tentatively estimates the even-foot length

for a board of a given maximum merchantable

width and decides if a width reduction of 2

inches allows for a length extension of 4 or

more feet.

The edgerman should have definite instructions on the green width required for each

width class manufactured in the mill. Basically

these widths depend upon an allowance for

shrinkage in drying, usually 1/16 inch per inch

of width, and an allowance for planing, usually

1/16 inch per face planed. These allowances are

added to the actual width standards set up for

yard items in the published grading rules of the

association and species concerned.

Wide pieces should be ripped into any series

of widths that will raise the grade of one board

above that of the wide piece. If no grade rise is

possible, the piece should be ripped to produce

a board 12 inches wide and the others as wide

as possible, but normally avoiding 7-, 9-, and

11-inch widths. Where possible, wide pieces

should be ripped so as not to intersect a knot

that may fall out during seasoning, nor should

material be ripped so that the pith is at the

edge.

The trimmer operator trims to produce a

merchantable board of the maximum even-foot

length possible. Usually a 2-inch allowance in

excess of the even-foot length is made when

trimming. . • , -

Milling Hardwood Logs , ', ,.'

Sawed hardwood is mainly channeled to two

outlets, (1) factories using material of random

width and length, or (2) construction fields

using ipaterial of specified sizes. The basis for

grading for the factory outlet is the degree to

which the material can be worked into relatively clear cuttings. Specifications for construction

material are designed mainly to assure that

strength properties will be adequate. Usually

material dominantly free of defects commands

a higher price in factory outlets, whereas the

construction fields can use to better advantage

material containing defects but otherwise fulfilling strength requirements. If the mill can

sell construction material, the lower-grade logs

or lower-grade sections of quality logs are

usually sawed to such items. The change from

factory material to construction items varies

with local conditions, but operators normally

try to saw material grading below No. 2 Common into construction items.

The market price per thousand board feet for

upper grades of factory lumber usually increases with stock thickness. Recommendations
92 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

cannot be made that all small mills should cut

thick stock, because the limited production at

a small mill can result in excessive handling

costs. The cutting policy with respect to the

type of products from the lower-grade portions

and the thick stock from the higher-grade portions should be determined for each individual

mill.

The price structure for the standard grades

for the factory outlet is such that No. 3 Common usually fails to return ' production costs,

No. 2 Common approximates costs. No. 1 Common yields a moderate profit, and Firsts-andSeconds returns a large one. For Firsts-andSeconds and No. 1 Common the market price

increases appreciably with thickness ; for No. 2

and No. 3 Common in factory outlets the price

advantage for thick stock is inappreciable. For

this reason the higher-quality material is

sawed into items of random width and length,

and the lower-quality material into items of

specified widths, thicknesses, and lengths.

The actual sawing practice for grade-sawing

factory lumber should be to work the highgrade material from the better faces by taper

sawing and then to turn to a different face as

the grade drops below that promised by adjoining faces. This process of working around

the log is usually profitable if it results in raising the grade from No. 3 Common to No. 2

Common.

As the log is transferred to the carriage, the

sawyer should decide on how to divide it into

four cutting faces and on the probable sequence

to be followed in sawing them. Deciding on one

face automatically fixes the other three. A mirror at the deck end of the track reflecting a

view of the end farthest from the sawyer as

the log is against the knees is helpful in judging the influence of end defects in determining

faces and probable sawing sequence. In the following description, face 1 is to the saw, face 2

on top, face 3 against the knees, and face 4 on

the bolster for initial sawing.

For clear, straight, sound logs with the pith

at the approximate center it makes no difference how the log is divided into faces, and

the cutting sequence from one face to the next

is that involving the least delay. Thus, at mills

turning down, the cant is turned down 90°. At

mills turning up, the cant is turned at least

180° from the first face. If the pith is off center,

the log should be placed so that one face is

perpendicular to the longest radius.

Logs with straight cracks are placed so that

the crack is at the board edge that is to be

taken out in edging (fig. 116, A). The log is

placed so that the crack coincides with the

radius that is 45° to the bolster and toward the

saw. If, however, face 2 promises high-quality

material and hence should be taper-sawed, a

slab is taken from face 4 before turning to face

1. At right-hand mills turning down, the cutting sequence usually is face 1, 2, 3, and 4. At

right-hand mills turning up, the sequence is

usually face 1, 3, 4, and 2.

Logs with spiral cracks (fig. 116, B) are

placed so that one end of the crack is as for

logs with straight cracks and the damaged zone

is downward and back toward the knees. At

mills turning down, the first face is usually

sawed until the crack appears on a board edge,

after which the other faces are successively

worked; but where spiral cracks extend for

one-third or more of the circumference, the

unaffected faces are sawed deeply before short

pieces are cut from affected faces. At mills

turning down, face 1 is worked lightly, face 2

deeply, and the cant finished on face 3. At mills

turning up, face 1 is worked lightly, face 3 is

slabbed, face 2 is worked deeply, face 1 is

worked nearly to the pith, and then face 3 is

finished.

B

FIGURE 116.—Sawing procedures for cracked logs. A,

For log with straight crack; B, for log with spiral

crack.
\ ~

SMALL SAWMILL OPERATOR'S MANUAL 93

Shake, rot, or spider heart (several splits

radiating from the pith) that is restricted to

the center does not influence the manner of

dividing the log to faces or sawing sequence.

The unmerchantable core is boxed and discarded. Logs with shake or rot in the outer zone

are placed on the carriage in such a way that a

cutting face is parallel to the straight line connecting the ends of the arc of shake or the long

axis of the rot area, and the face affected is

sawed last.

Logs with worm holes (grub, shot, or pin)

should be placed on the carriage so that faces

visibly free from holes are sawed before the log

is turned to the affected areas.

Indicators of degrading defects listed up to

this point usually are detected from the ends

of the log. Indicators detected from surface inspection, such as adventitious bud clusters,

bird pecks, bulges, bumps, burls, butt scars,

cankers, conks, holes, knots, overgrowth, and

wounds, can be treated as a group insofar as

they influence the manner of dividing the log

into faces and the sawing sequence. Logs will

include the full range between those with few

indicators affecting a localized area and those

with many that are dispersed over the entire

surface. Surfaces free of indicators are determined as the basis for initially placing the log,

and it is then successively turned so as to cut

the high-grade material from these faces before deep cuts are made into the defective ones.

Thus, for a log with three high-grade faces, the

defective one should be slabbed and turned

down 90° or up 180°, depending on mill practice,

the defective face being sawed last.

Logs with two adjoining high-grade faces are

slabbed on each of the low-grade faces. On

mills turning down, they are then placed with

one high-grade face up and the other to the

saw. After the first high-grade face is sawed

the log is turned down 90°. Where turning up

is practiced, the log is placed with one highgrade face to the saw and the other down, and

after the first face is sawed, the log is turned

up 90° apd successively worked around.

Logs with two opposite high-grade faces are

placed with one to the saw regardless of the

turning method. After the high-grade material

is sawed from this face, the log is turned down

90° at mills having turn-down equipment, slabbed, and turned down 90° to saw the high-grade

material from the other good face. At mills

having turn-up equipment, the first face is

sawed, the log is turned 180°, and the other

good face is sawed.

A log having a single high-grade face is

placed with this face against the knees. At mills

471449°—58 7

turning down, a 90° turn is used for successive

faces. At mills turning up, the turning sequence

after the first face is sawed is 180°, 90°, and

180°.

Where a clear face adjoins one having one

or more defects that seem likely to be removed

in edging, the log is placed so that these defects

will be near the edge of the defective face.

Cankers, conks, holes, and large dead knots,

however, are indicative of extensive defects not

likely to be removed by edging, and the sawyer

should center them on the poor face (fig. 117).

FIGURE 117.—Method of sawing log with small sound

knot and large dead knot.

Logs with sweep should be placed on the

carriage with the crook out, and the four faces

should be successively worked in the sequence

dictated by turning equipment. Better grade

recovery usually results when the widest

boards are cut from the faces that are at the

top and bottom with reference to the first face

sawed.

It is important that the location of faces be

fixed in accordance with the factors outlined.

The high-grade faces are usually sawed parallel

to the bark and the low-grade ones in the most

convenient way to speed up the work. If a highgrade face is opposite a low-grade one, the

good one should be sawed parallel to the bark.

This can be done either by placing the poor

one against the knees and setting out the small

end of the log, or simply by placing the good

face against the knees and slabbing the poor

face first.

If the high-grade faces are opposite each

other and the log is characteristically free of

defects nearly to the pith (as with red oak, ash,
94 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

and yellow-poplar), one good face is placed

against the knees and the other is partially

sawed without regard to parallelism. If the

log is characterized by interior defects that

extend beyond the pith zone (as with sugar

maple and birch), the small end is set out

enough to permit cutting a slab of uniform

width the full length of the log. When the opposite good face is turned to the saw, this

process is repeated; but after this face is cut

and before the log is turned to another, the cut

is "straightened" by retracting the taper levers, setting the small end back against the

knees, and sawing the face to produce a cant

with opposite faces parallel. The purpose of this

is to take out the taper from the low-grade

material in the core instead of from high-grade

material in the outer zone.

When slabbing parallel to the bark, the face

of the slab should be the minimum width required by the prospective board grade—GVo

inches for grades above No. 1 Common and 3V^

inches for No. 1 Common or lower. With any

face, a 4/4 cut is usually taken next to the slab

in order to minimize edging waste, but if the

face is opposite a previously sawed one, the

sawyer slabs so that the final piece will conform to the size requirements, thicknesses, or

widths of the intended item. Faces indicative of

high-grade material are sawed deeply, those

indicative of low-grade lightly. The usual practice is to continue sawing a face until the grade

drops to that promised by the adjoining faces.

This progressive turning continues until either

the central portion is sized to meet construction item specifications or until the grade improvement fails to pay. For small mills that

specialize in cutting factory lumber, such turning is justified as long as lumber better than

No. 3 Common can be cut.

Procedure for Edging

Material for factory outlets is normally

edged to get the maximum width possible in

inches and fractions ; for construction item outlets, it is edged to conform to definite width

specifications.

The minimum width for dry factory lumber

is 6 inches for Firsts-and-Seconds and 3 inches

for Common. Normally, a shrinkage allowance

of TV inch per inch of width is made, so that

green Firsts-and-Seconds should be at least

6% inches and green Common at least 3 3/16

inches in width. Boards are usually edged with

the narrower (bark) face up.

Boards below Firsts-and-Seconds are edged

so that the surface area of the wane or rot left

on the board is approximately equal to the area

of sawed, sound face of the edging (fig. 118).

For Firsts-and-Seconds, wane and rot cannot

exceed one-twelfth the surface measure nor

aggregate more than one-half the length of the

piece. Shakes and splits in Firsts-and-Seconds

cannot aggregate in inches more than twice

the surface measure of the piece in feet nor diverge more than 1 inch per foot of length unless they aggregate 1 foot or less in length.

They should be removed by ripping or trimming if they violate this requirement in Firstsand-Seconds or extend more than one-third the

length of the piece in Common grades.

•¡i>i¡>>>¡>>>»»»»»

w

B

'in>>}}}r}i}>n>>>i>Trr.

>,,,>>>>JfJJ^ff/J//J>l))J,,,,r^

FIGURE 118.—Examples of first boards under slabs requiring edging and trimming in grades below Firstsand-Seconds. A, From butt log, edged; B, from convex face of crooked log, edged and trimmed ; C, from

concave face of crooked log, edged.

All pieces exceeding 16 inches in width

should be ripped if the grade of the resulting

two boards does not fall below that of the wide

piece.

Boards- are ripped to raise the grade when

one-half or more of the original surface measure is raised at least one grade.

Material for construction outlets is edged to

conform to definite width requirements. Items

may be made from a limited number of species

and sized to a restricted series of widths, thicknesses, and lengths—as for car stock and construction boards. The sawyer, edgerman, and

trimmer must know the size, species, and allowable-defect provisions of grading rules for

such items. The -^j-vaçh allowance per inch

of width should be made to take care of shrinkage from the green to the dry condition. Material in thicknesses exceeding 3 inches is normally edged on the headsaw. A high percentage

of all construction items is produced by the

headsaw from squared cants and requires no

edging. The small amount requiring it is edged

according to the size and quality specifications

for the particular product. These products are

usually so diverse that general edging instructions cannot be set down.
SMALL SAWMILL OPERATOR'S MANUAL 95

Procedure for Trimming ' '

Each piece should be trimmed 2 inches over

the nominal foot, and boards below Firsts-andSeconds should be trimmed so that the surface

area of the wane or rot left on the board is approximately equal to the area of the sawed,

sound face of the trim (fig. 118). Where the

sawed face does not reach the board end

(feather ends) (fig. 118, B), the termination of

the sawed face is regarded as the board end.

For Firsts-and-Seconds, wane or rot in excess

of one-fourth the affected area within 1 foot of

the end must be trimmed, and at least one-half

the area of this last foot must have clear face.

The rule for edging boards with splits in Firstsand-Seconds also applies to trimming them;

they are trimmed so that splits aggregate no

more in length in inches than twice the surface

measure in feet, nor diverge more than 1 inch

to the foot in length, except when 1 foot or

shorter.

For construction outlets, each item is trimmed to conform with specific length requirements and with wane, shake, or crack provisions for the item as listed in the applicable

grading rules.

Green Firsts-and-Seconds should be cut at

least 6V2 inches wide and green Common at

least 3I/4, inches wide.

Green stock coming from the saw should be

of the following minimum thicknesses: 4/4,

ITV inches; 5/4, 1 5/16 inches; 6/4, 1 10/16

inches; 8/4, 2 2/16 inches. To insure this, the

setworks should be accurately adjusted to permit advance at 1/16-inch intervals, and proper

allowance made for saw kerf and machine

variation. Few small mills can produce lumber

within j\ inch of the desired thickness.

Digest of Rough Hardwood Lumber Grades

for Factory Outlets

Maximum grade recovery involves a series

of operations. The tree length must be properly

subdivided into logs ; the logs must be properly

placed on the carriage and turned to a new

face as required ; edging and trimming must be

carefully done; and proper drying methods

must be used. A knowledge of grade rules is

the basis for decisions governing most of these

operations.

Special rules apply to particular species, but

only the most essential requirements of the

three grade segregations, First-and-Seconds

and No. 1 and No. 2 Common, are discussed

here as a first step in understanding hardwood

grade rules. With this as a framework, the

special rules that apply to certain species can

be obtained from rule books published by the

National Hardwood Lumber Association, 59 E.

Van Buren Street, Chicago 5, 111.

Actually the sawyer, edgerman, or trimmerman will not have time to do any close grading,

but must depend on his own mental picture of

the grade classification gained by practice grading as described below.

With a lumber-scale rule and crayon, examine any hardwood board in the yard to determine whether it is properly manufactured and

which side is the poor face. To decide if the

board has been properly manufactured, note

whether the cutting areas are full thickness

when "shipping dry." Nominal inch lumber

must be at least 1 inch thick in the thinnest

part of the cutting area, 5/4 lumber at least

114. inches thick, and so on. Lumber 1 to 2

inches thick that varies more than I/4 inch in

thickness is rejected as miscut.

Hardwoods, with minor exceptions not considered here, are graded from the poor face—

the side that will grade the lowest.

From table 15, the requirements for a given

grade are readily determined. It is suggested

that the sample board be checked against the

grading rules, starting with those for the top

grade and progressing through those for the

lower grades until the rule is found that fits

the board and thus fixes its grade.

The detailed steps necessary in determining

grade are:

1. Get the surface measure (SM) of the board with

the lumber-scale rule.

2. Assume an estimated grade for the board.

3. Determine whether the board meets the size requirements (cols. 2 and 3, table 15).

4. Mark off, on the poor face, all clear-face cuttings

that equal or exceed the size requirements of the

estimated grade (cols. 4 and 5, table 17), drawing

straight lines as would result from ripping or

crosscutting or both (fig. 119).

5. Determine the number of cuttings conforming

with requirements for the surface measure taken

and estimated grade (col. 6, table 15), dropping

any fractions.

6. Measure, for not more than the allowable number

of cuttings, the width in inches and length in feet

of each cutting, making no allowance for saw cuts.

7. Multiply the width (inches and fractions) by

length (feet and fractions) of each cutting.

8. Add all results obtained under step 7.

9. Determine the number of units required for the

surface measure and estimated grade (col. 7,

table 15).

10. If the total obtained by step 8 equals or exceeds

the number of units determined in step 9, the

board is at least as good as the estimated grade.

Examples of this procedure are given in table 16.

In addition to the requirements listed in

table 16, there are limitations of defects on the

piece outside of the cuttings. For Firsts-andSeconds these limits are: (1) For wane, 1/12 of

surface measure (9-foot scale x 12 = 108

square inches) ; (2) for pith, when the length
96 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE '•/

r'

*

s

t

8"

t

8X5 = 40 UNITS

1

1

é

ê\\

lOX 6= 60 UNITS

+

10"

t—^~^ ~ 1

.-^1 -.-

A "' ', \c

.1 w 1 ^ -r ' k 1

* 4 >|.

4X5= 20 UNITS 10 X 7= 70 UNITS

^ •

e

^A^'J^.'i.NJTS

4X5' 20 UNITS

I."!"3X 33/4= IÔ"U~NITS"

10X7= 70 UNITS

_ 3" ^ -, ' > < T'' 1

-« 24 ^4 * ^4 +

1i" 4^X2| =12 UNITS « _ .•_. .

m '

^4

5X7^ = 36 UNITS 1 ; 8 X 3^= 26 UNITS fl"

t

1

^ 14' _> +

r»' r

3 >j < ^4 = 4

4-X 2? = 12 UNITS !' _> .

«;

5X5¿ = 26 UNITS

. i-j^^. .--1)1 5X5| =29 UNITS

;¿r

12 ' 1

' .

_..:?.. •

26

Ijl 29

t

t

.^^-^ 7 ,>i

FIGURE 119.—Examples of how to delineate cuttings and compute areas for hardwood grade classification. A, B,

and C, pieces with knots in center; D, E, and F, pieces with knots along edges.

of pith in inches equals the scale in feet (9-foot

scale = 9 inches) ; (3) for a knot or hole, when

its size in inches equals 1/3 the scale in feet

(9-foot scale x 1/3 = 3 inches), the boundary

of a sound knot being taken where the trunk

wood and branch wood meet, as in figure 120;

for a split, when its length in inches equals

twice the scale in feet (9-foot scale x 2 = 18

inches). For No. 1 Common, pith is limited to

Vè the length, and for No. 2 Common, it is

limited to % tlie length of the board.

. A cutting is a portion made by imaginary ripping, by cross-cutting, or by both. In measuring

the dimensions of cuttings, no allowance is

made for saw cuts. Clear-face cuttings are free

of defects other than sound burls, permissible

streaks, and similar acceptable blemishes on

the grading face of the board; the other side

may have sound defects, but rot, pith, shake,

and wane are excluded. Sound cuttings are free

of rot, pith, shake, and wane on the face or

back.

There is no difference in grading because of

thickness, 1/4, 1, 2 inches, and all other thicknesses being graded on the surface-measure

scale.

Lengths are measured back to the full foot.

A piece 11 feet, 11 inches long is counted as 11

feet. Only 50 percent of odd-length pieces are
SMALL SAWMILL OPERATOR'S MANUAL 97

TABLE 15.—Summary of hardwood board and cutting requirements for three key standard grades '

Grade

Smallest

board

permitted

Smallest

cutting

permitted ^

Maximum number ' ' ,

of .;

cuttings ' '

Least

number

of

units

Width required 'Length Width Length

(1) (2) (3) (4) (5) (6) (7)

First and

Seconds

(FAS)

In.

6

Ft.

8

In.

4

or

3

Fi.

5

or

7

SM ,'- ;•;

and not more than 4

4 , -

SM

Alternate for boards 6- to 15-foot SM: 1-1

4

SMx 10

SMx 11

No. 1

Common

3 4 4

or

3

2

or

3

Boards 1 foot SM, 1

Boards 2 feet SM, 1

Boards 3 to 4 feet SM, ' - . 1

2

Boards 5 to 7 feet SM, 2

3

Boards 8 feet SM and over:

SM +1

SMx 12

SMx 9

SMx 8

SMx 9

SMx 8

SMx 9

SM x8

3

No. 2

Common

3 4 3 2

SM "

2

SM

Alternate for boards 2 to 7 feet SM: hi

2

SMx 6

SMx 8

' Digest from National Hardwood Lumber Manufacturers Association Rule Book.

2 The smaller of the two widths given, or the smaller of the two lengths, governs FAS and No. 1 Common.

Example: Cutting may be 4 in. by 5 ft., or 3 in. by 7 ft., for FAS.

ä SM=surface measure.

admitted, those in excess being taken as the

next lower even foot.

All thicknesses of random-width lumber are

scaled surface measure with a lumber-scale

rule'' (fig. 121). They are tallied as the full-foot

figure between the vertical lines. If two read

exactly on the half-foot mark, one is counted

at the lower and the other at the upper even

foot. Surface measure is determined by estimating or measuring the length of the piece,

then laying the lumber rule across it so that the

metal end plate touches the board edge. The

rule gives the surface measure directly in board

feet according to the length of the piece.

These condensed specifications and interpretations apply to "shipping-dry" lumber. In

actual manufacture, it is necessary to remember that shrinkage must be allowed for when

cutting green lumber to meet the minimum size

requirements of " shipping-dry" materials. A

5 Lumber-scale rules are manufactured by : American

Rule Co., Nashville, Tenn. ; Frank R. Buck and Co.,

2133 Touhy Ave., Chicago, 111.; Cleveland Rule Co.,

2190 W. 59th St., Cleveland, Ohio; Lufkin Rule Co.,

Saginaw, Mich.; American Sawmill Machinery Co.,

Hackettstown, N. J.

general rule is to allow about j\ inch of

shrinkage for each inch of width or thickness.

For example, the minimum width for "shipping-dry" Seconds is 6 inches; a green board

sawed less than 6% inches wide is, therefore,

likely to be less than 6 inches wide when "shipping-dry."

Sawing Oversized Logs

There is no efficient method of cutting, by

the "sawing-around" procedure, logs that are

too large for the headsaw. The relation between

saw diameter and maximum log diameter is as

follows :

Saiv diameter Log diameter i

(Inches) (Inches)

48 28

52 30

56 33 - ''

60 36

Logs having diameters slightly larger than

those tabulated may be sawed by using approximately a one-eighth turn instead of the onefourth turn common with the "turning-around"

method, after as much is taken as can be sawed
98 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

M-B3463-F

FIGURE 120.—-Defective areas of a hardwood board

marked off. Left, knots; right, splits and rot.

FIGURE 122.—Successive steps in sawing oversized logs.

A, Initial cut; B, turned up 90° from A and sawed:

C, turned 90° from B and sawed; B, turned down

90° from C and sawed; E, turned down 90° from 7?

and sawed.

end, so that the ensuing saw lines will follow

planes parallel to the first saw line taken. Saw

stock items, discontinuing before reaching the

center (fig. 122, C). Turn the log down 90° and

saw stock items until beyond the center (fig.

122, D), then turn down 90° and finish (fig. 122

E).

Powered drag saws and chain saws are sometimes used to reduce oversized logs to segments

that can be cut on the headrig.

from one face. Ultimately the many-sided piece

thus formed can be squared and sawed as in

normal procedure. This method is wasteful of

material and time.

Logs with diameters nearly twice the height

of the portion of the saw above the bolsters

can be reduced as follows :

Set the log to the saw so that the saw line

will be a distance from the face of the knee

equal to the height of the saw above the bolsters, and cut a line (fig. 122, A).

Dogs must be fixed to hold the log firmly,

and feed must be slow. Turn the log up exactly

90" and saw stock items, discontinuing before

reaching the log pith or center (fig. 122, ß).

This series of cuts should extend exactly to the

first saw line. Turn up 90' and set out the small

3- 4- 5- ' 6- ?• 8- ' 9- ' 1-0 I hi <

3- .4- 'S" ' e- 7- • 8- 'S- ' /

.1.1,1^1 |-*l,l,l,|5|,|,|,|6| 7- a- ^

FIGURE 121.—Lumber-scale rule used in measuring

lumber.

Size Standards

Lumber, timbers, and ties must meet the

precise size standards given in the official grading-rule books of the lumber associations concerned with the species in question. With timbers and ties, the sizing problem concerns allowance for sawing inaccuracies; with lumber

and light framing, it concerns allowance for

sawing inaccuracies and, in addition, a greento-dry shrinkage allowance.

For most species an allowance of ^^^ irich

for each inch of width or thickness is adequate

to offset shrinkage from the green to the airdry condition. Thus, green lumber 34/32 inch

thick should meet the requirement for 1-inch,

air-dry, rough stock. Softwood yard items of

lumber and light framing are usually surfaced,

and may be patterned. The rules establish standard dressed dimensions for such material, and

the actual minimum sizes required from rough

lumber before dressing can be found by adding

a Vfj-inch dressing allowance to the required

dressed dimensions. A nominal 1- by 8-inch S4S

yard item is actually ff by YVí inches and

can be made from rough, dry lumber SI by

T-'/ji inches in section, which when green is

fi by SVB inches.
SMALL SAWMILL OPERATOR'S MANUAL ' . 99

TABLE 16.—Tabular method of analyzing hardwood lumber for grade

Case

No.

Figure

No.

Surface

measure

Estimated

grade

Does

board

meet

size

requirements?

Minimum size

of clearface cuttings

allowed

Clear-faced

cuttings

Actual

dimensions

of

cuttings

units

per

cutting

Total

units in

allowable

number

of

cuttings

Required

units

Is

board

as

good

In

board Allowed

as estiWidth Length Width Length

mated

grade?

1 119A

119B

119C

119D

119D

119E

119F

10

10

10

9

9

9

9

FAS

FAS

No. 1

Common

FAS

No. 1

Common

No. 1

Common

No. 2

Common

Yes

Yes

Yes

Yes

Yes

Yes

Yes

In.

4

3

4

3

4

3

4

3

4

3

4

3

3

Ft.

5

7

5

7

2

3

5

7

2

3

2

3

2

No.

2

No.

2

In.

8

10

4

10

3

4

3

10

5

8

8

.5

^H.5

iK

SK

5

5

3

3

Ft.

5

6

5

7

4

5

7

7H

3M

7H

m

2M

2M2

m

2M

No.

40

60

20

70

12

20

No.

100

No.

100 Yes

2 2 2 90 100 No

3' _. 4 3 102 80 Yes

2 2

70

36

26

26

36

12

26

29

12

12

7

4 62 90 No

5 3 3 74 72 Yes

6 3 3 67 72 No

Ö 7.... 4 74 54 Yes

29

26

1 A board failing to qualify in a higher grade may be classed in the next lower grade without further checking

if the total number of grade units found in testing for the higher grade equals or exceeds the total required for

the next lower grade.

Circular and band headrigs are not precision

machines. As much as 75 percent of the production will be sV inch or more outside in interval intended. If no allowances were made for

such variability, as much as 30 percent of the

cut would be below the size standards required.

The allowance necessary to counteract this

variability may be as little as -jV inch or more

than /T inch. The majority of sawyers allow

2/32 inch, or set for li/s inch thickness when

sawing inch lumber. If any scant lumber is produced by a mill set to cut li/g-inch stock, the

owner needs to check the machine causes and

correct them.

It is a widely held belief that a saving in saw

kerf or precision will not be had unless an extra

board results. The rationalization follows the

pattern that nine boards must be taken with

a %-inch kerf before any saving results over

the 14-inch kerf. It can be demonstrated diagrammatically that an increase of approximately 2i/¿ percent in softwood footage results

from each g^a-inch decrease in saw kerf, and

a comparable saving results from improved

precision in sizing.

Under normal conditions, buyers pass up

small-mill lumber in favor of that from larger

mills. This is only partly due to factors beyond

the control of the individual operator. The

small-mill operator can size his product as accurately as does the big mill (fig. 123) but better sizing is the reason most commonly advanced for purchaser preference for the product of larger mills. By correcting the causes of

inaccurate sizing, the small-mill operator can

gain perhaps more benefit than by almost any

other improvement in efficiency. Besides the decreased sales resistance, a greater recovery of

salable products accrues because less allowance

must be made for thickness variation; hence

the average of all boards can be thinner. As

shown by figure 123, most mills cut lumber excessively thick because they cannot be set closer

to the required thickness without cutting an

important percentage of stock under minimum

thickness.

The causes of inaccurately cut lumber are

(1) faulty condition of the saw, which may be

due to teeth that are out of line with the perimeter, holders or teeth out of line with the saw
100 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

M-82223-F

FIGURE 123.—Thickness variation in inch lumber produced by A, a sash gang saw; B, a good circular saw; C, average of eleven band saws; D, average of six circular headsaws. Each pile has 100 blocks. The blocks in each

vertical tier for each pile are uniformly thick but differ one thirty-second inch in thickness from those adjacent.

Tallest tier in each represents the thickness set for. Comparative range of thickness in each pile indicates sash

gang to be most accurate and average circular least accurate.

plane, excessive or uneven swage, teeth that

are dull on one side, or incorrect tension; (2)

worn bearings in the mandrel, the carriage

wheels, or the setwork; (3) poor installation of

the carriage and saw; (4) lodging of chips between the log and headblock or on the tracks;

(5) careless setting or miscalculation; (6) inaccurate manipulation of the dogs, or use of

types of dogs mechanically unfit to hold the log

firmly; and (7) frozen timber or unequal

stresses in the wood.

Common Causes, Results of Faulty Sizing

1. Dog board thicker or thinner at top than

at bottom edge.—Faulty alinement of the saw

and headblocks will cause unequal thickness of

the dog board. The knee face should be at right

angles to the top of the bolster, and the saw

plane should be parallel to the knee face. The

specific cause of this type of inaccurate sizing

can be in the track, carriage, or saw mandrel.

The cause of the misalinement can be checked by stopping the carriage so that the headblock is opposite the saw, placing one leg of a

carpenter's square along the top of the bolster

and the other leg first along the face of the

knee and then flat against the saw. If either the

saw or the knee face fails to show a rightangle relationship to the bolster top, the adjustment is faulty. Each headblock should be

checked. The simplest way to correct this difficulty usually consists of leveling the track,

but where faulty alinement is due to worn

headblocks, they should be replaced. Bolsters

should be firmly anchored to the carriage bed.

2. Dog board thicker at one end than other,

or varies in thickness between ends.—Variations in thickness along the length of the dog

board may be due to a twist or dip in the track,

to side play between carriage frame and wheels,

to misalinement of knees, or to end play in the

saw mandrel. Track alinement can be checked

by stretching a fine brass wire just clear of

the top of the guide rail from the deck to a distance of a carriage length beyond the saw, so

that any deviation or dip of this rail can be

detected. Side play can be detected by giving
SMALL SAWMILL OPERATOR'S MANUAL 101

the carriage frame a vigorous sideward shove.

The check on knee alinement consists of setting the faces of the knee so that they are

about 2 inches from the front of the bolsters.

To do this, the carriage is stopped so that the

front knee is opposite the saw. The exact distance from saw blade to knee face is then

measured, the place on the saw where measurement is taken being marked; the rack of the

knee should be tight against the pinion of the

set shaft. Next, the carriage is moved to bring

the next headblock opposite the mark on the

saw and measurement is taken as for the first

block as before. This procedure is repeated for

all headblocks. All readings should be identical.

Differences in readings may be due to a sprung

set shaft, to a worn rack and pinion, or to loose

or worn keys on the pinion. Most mills provide

for some adjustment, either by resetting the

rack or by recoupling the segments of the set

shaft, but worn parts call for replacements.

End play of the mandrel can be detected by

trying to force it toward or away from the

track, using a lever on the driver pulley.

0 1 2 3 4 5 6 7 a 9

0 o 20 •a? 40 50 60 7C 80 90

0 KX) 200 300 400 500 60p 700 BOO 900

Q IjOOO 2 3 4 5 6 7 8 9 10 11,000

FIGURE 124.—Board-peg lumber tally board.

8\ 80

3. Failure consistently to cut boards of similar thickness.—Inconsistent thickness may be

due to causes already listed or to the dogs, setworks, or saw. One source of inaccurate sizing

is inherent in the setworks mechanism of many

small mills, the pinion-rack connection being so

loose that the knee can be moved backward or

forward as much as one-half inch without recourse to the set lever. Such looseness also results from worn gears. With fast feeds this

looseness can cause a light cant to pull toward

the saw ; or, if unbalanced stresses are present

in the cant, one or more headblocks can be pulled toward the saw. Faulty sizing also results

from play in the setwork gears, or in the pawl

contacts. Either is usually traceable to worn

keys, cogs, or pawls. Faulty sizing may also be

due to miscalculation by the setter or to lack of

a fixed backstop, which makes it diificult to set

the exact interval desired in setworks.

TABLE 17.—Lumber tally footage by lengths,

widths, and thicknesses

FIGURE 125.—Dial-pointer lumber tally board.

Nominal Footage tally for length of—

cross

section

(inches) 8 10 12 14 16 18

feet feet feet feet feet feet

Board Board Board Board Board Board

feet feel feet feet feet feet

1 X 3.. 2 Wl 3 33^ '4 43^

1 X 4__ 2% SVs 4 4% •5% 6

1 X 6__ 4 5 6 7 8 9

1 X 8._ 5^ 6% 8 9% 10% 12

1 X 10__ 6H Ws 10 11% 133^ 15

1 X 12._ 8 10 12 14 16 18 ;

V/2X 4._ 4 5 6 7 8 9

VAX 6.. 6 7^ 9 103^ 12 nVi

l^x 8._ 8 10 12 14 16 18

VAxlO.. 10 12^ 15 17^ 20 22J^

Ij^xl2__ 12 15 18 21 24 27

2 X 4_. 5^ 6% 8 9% 10% 12

2 X 6__ 8 10 12 14 16 18

2 X 8__ 10% 13^ 16 18% 21% 24

2 X 10_. 13}^ 16% 20 23% 26% 30

2 X 12-_ 16 20 24 28 32 36

3 X 4__ 8 10 12 14 16 18 Î

3 X 6_- 12 15 18 21 24 27 .

3 X 8_. 16 20 24 28 32 36

3 X 10-_ 20 25 30 35 40 45

3 X 12 _ 24 30 36 42 48 54

4 X 4-. 10% 133^ 16 18% 21% 24

4 X 6__ 16 20 24 28 32 36

4 X 8__ 213^ 20% 32 373^ 42% 48

4 X 10_- 26% 33 J4 40 46% 5334 60

4 X 12_. 32 40 48 56 64 72

6 X 6-. 24 30 36 42 48 54

6 X 7._ 28 35 42 49 56 63

6 X 8-_ 32 40 48 56 64 72

6 X 10__ 40 50 60 70 80 90

6 X 12.. 48 60 72 84 96 108

7 X 9__ 42 Ô^Vo 63 7Sy2 84 94>^

8 X 8__ 42% 5334 64 74% 85% 96

8 X 10_. 5334 66% 80 93% 106% 120

8 X 12„. 64 80 96 112 128 144
102 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

Faulty sizing from slack dogging shows up

in fast feeds or when sawing cants that have

unbalanced stresses ("springy" timber). Some

types of dogs are better designed to hold the

cant firmly than others. The "boss" dog normally grips firmly and draws the cant tight to

the face of the knee. Dull tooth points, knots,

or loss of the correct hook when the point is

sharpened may result in faulty sizing.

tSPECIES) (GRADE) ¡THICKNESS) ¡DATE)

WIDTH LENGTH 1 2 3 4 5 6 7 a 9 10 II 12 13 14 15 PCS

3 6

a in 3

10

12 II Z

14

16 III 3

4 6

a II 2

10

12 III 3

14

16 m 1 k

5 6

8 1 1

10

12

14 1 1

16

6 6 Hü II 7

a Mí «« nu- nu 1 21

10 III 3

12 rt*i 5

14 III -?

16 m pu ll 12

8 6

a

10

12

14

16

10 6

a

IÛ

12

14

16

12 6

a

10

12

14

16

1 2 3 4 5 6 7 8 9 10 II 12 13 14 15

The saw can be the source of faulty sizing if

the mandrel has end play, if the lead is not

correct, or if the fitting of plate or teeth is incorrect. The saw has a tendency to deviate

when overloaded, as when using excessively

fast feeds, cutting hard or frozen woods, or

making deep cuts. Obviously, a dull saw is more

erratic than a sharp one.

Tallying and Grading

A daily tally of green lumber cut at the mill,

separated by ownerships, is kept by small cus-

(SPECIES) (GRADE) (THICKNESS) (DATE)

SURFACE

MEASURE 1 2 3 4 5 6 7 8 9 10 II 12 13 14 15 NO.

PCS.

TOTAL

SURFACE

MEASURE

1 m 5 5

2

3

4 m m fi 32

5 m im 1 II SS

6 III .? IS

7 nu m II 12 84-

8

9

10

II

12

13

14

15

16

17

18

19

20

21 .

22

23 .

24

1 2 3 4 5 6 7 8 9 10 II 12 13 14 15

FIGURE 126.—Tally form for softwood lumber, showing

total number of pieces of various widths and lengths

for a given species, grade, and thickness.

FIGURE 127.—Tally form for hardwood lumber, showing

total number of pieces for each board foot of surface

measure, and total surface measure. Quantities

shown calculated on basis of steck 1 inch thick.
SMALL SAWMILL OPERATOR'S MANUAL 103

torn and tie mills. As a rule, other small mills

depend upon recording the amounts of product

shipped out of the yard and the amounts in the

yard as shown by periodic inventories. Large

mills usually record the daily production at the

green chain ; or, if the product is shipped green,

by truckloads.

When production does not exceed 1,200 board

feet per hour, a total footage tally can usually

be taken without adding to the crew. For softwood or custom records on hardwoods a board

peg (fig. 124), a dial pointer (fig. 125), or some

similar device is used. It is operated by any

crew member in position and with time to check

items—usually the pile-out man. The workman

memorizes the footage outrun for the range in

sizes normally produced (table 17) and places

pegs or moves pointers to record the footage

summation.

Usually all species are lumped together, but

a series of boards may be used where separate

tally by species is possible. At some custom

mills where edging is done on the headsaw, the

sawyer records items on a tabulation sheet.

Headings are written in for each size (length,

thickness, and width) normally sawed and a dot

placed for each item sawed. Footage is computed from these records. Where a total item

count is desired, as in tie mills, a metal-cased,

patented counter is available that registers

totals on dials with each pull of a trigger.

Hardwoods produced for remanufacturing

outlets are sawed to random widths, and a

special tally rule is used to get the surface

measure for each piece. An allowance of 5 percent for drying shrinkage is usually applied to

this green tally. Items are recorded by species,

thickness, surface footage (the board-foot tally

is computed from the thickness and surface

tally), and, if green grading is done, by grades

on special forms.

The occasional mill that sells green lumber on

grade, or that for other reasons practices green

grading, stations a grader beyond the trim saw

to mark the grade on each piece and enter the

footage on tally sheets (fig. 126 and 127).

Usually the pile-out men separate the stock to

the extent feasible to make loads of one grade,

species, or item, but the grader sometimes also

does the piling out where production remains

less than 1,500 board feet per hour.

At mills selling on a dry-grade basis and shipping rough lumber, the grader usually grades,

marks, and tallies the shipped material as the

piles are taken down. Items not in the grade being shipped are marked and segregated by

grades, bulk-piled, and tallied when shipped.

Grading of dressed lumber is done after

machining. Pieces not making the shipped

grade are bulk-stored in sheds and segregated

according to market requirements, such as

grade and pattern. Footage for dry hardwood

items is measured with a tally rule showing the

actual surface footage, with no allowance for

shrinkage.

SOME BUSINESS ASPECTS OF SMALL-MILL OPERATION

Efficient milling is not the only important

factor contributing to a profitable operation.

The actual cost of converting logs to products

approximates only about one-third of total

costs ; the other two-thirds consists of log costs

and sales expenses. The profit or success of the

business depends upon keeping total costs below sales values—in other words, sound business management. A lag of several months

exists between the time when investment is

made in logs and that when returns from converted products are realized. Lumber prices

rarely hold constant over such periods (fig.

128). Hence, success is greatly influenced not

only by how well the operator adjusts his costs

and volumes but by how well he anticipates

future sales values.

It is impossible to set up instructions that

guarantee correct evaluation of future trends,

but adjustments to meet prospective market

conditions can be indicated.

Several direct costs can be varied to some extent with the prospective market through such

measures as direct changes in wage and servicing costs, stumpage or log prices, transporting distances, size and quality of logs, and in

total log and lumber volumes carried. A low

price level tends to depress wages and stumpage prices, reduce hauling distances, and curtail

inventories of logs and lumber, as well as to

raise size and quality requirements ; a high one

reverses this tendency. Certain other costs cannot be varied so readily ; charges for taxes, insurance, depreciation, and management vary

only with the total annual production. An increase in total annual production reduces the

unit cost, and a reduction increases it. Volumes

tend to shrink as price levels recede, so that

normally these fixed costs increase per unit precisely when a reduction is required.

Fixed costs are relatively less for small mills

than for large ones ; hence, the small mills are

under less pressure to operate, and can more

readily suspend operations in a losing market.

Some protection from the effects of fluctuating

price levels can be gained through measures
104 HANDBOOK 27, U. S. DEPARTMENT OP AGRICULTURE

^

V

^

\

\

^>^

\

X,

\

]

<\

/'

^

/

>

s,

\

SJ

y

/^

\

L

/

\

Í

<.

\,

«

-^

/

1

1

[

\

/

\

ifÍM ft;

1

Uj

^ «1 O T> «a "tí Q •o Q

<0 T> T> >» •^ "^ tvi tM

(syviioa¡ X33J aavoa ooo'i y3d 3mvA sovusw
SMALL SAWMILL OPERATOR'S MANUAL 105

that reduce the inventory investment; for example, use of dry kilns permits faster turnover,

or investment in stumpage or logs can be

restricted.

Capital Requirements

The business mortality of small sawmill ventures is high. Aside from the hazards entailed

in fluctuating price levels, the greatest single

cause of this is usually the operator's failure to

appreciate all the costs involved and the sum required to conduct the operation. His misconception of costs leads him into unprofitable contracts. Underestimating the capital requirements leads to excessive borrowing, forced

sales, and loss of control of the business. From

a broader point of view, the effect of considerable numbers of poorly financed small mills undertaking impossible contracts and under constant pressure to liquidate is to weaken the

price structure of the lumber industry and

wreck the forest capital. It will profit a prospective operator to canvass his probable capital

needs thoroughly and to keep an accounting

system when operating.

The amount of capital required to start and

to keep going obviously varies with types of

operations and general business conditions. For

any operation, however, it can be broken down

into (1) investment in equipment; (2) investment in stumpage and logs; (3) costs of conversion and marketing; and (4) reserve for

contingencies.

To determine the equipment investment, the

type of operation undertaken must be decided

upon. Mill equipment is somewhat specialized

according to products made, log size, and hourly

output. An estimate of the total initial and installation costs includes this item.

The probable stumpage and log investment

can be estimated by determining the customary

prevailing arrangements for stumpage or log

purchases and estimating the total quantity of

stumpage and logs normally bought to insure

adequate supplies.

The probable capital investment needed to

carry conversion and marketing costs can be

estimated by approximating the total sum

spent over the normal period required to convert and collect. A suggested method is to list

the costs recurring daily for working days,

such as labor, fuel, and sustenance, and multiply these by the number of work days normally

elapsing between the time the trees are cut, if

the operator does his own logging, or the time

payment is made for logs delivered to the mill,

and the date when the receipts are at hand for

a definite turnover. To this total should be

added expenditures for repairs, licenses, taxes

including social security, legal fees, rent, and

insurance; interest on operating loans; and an

allowance for depreciation. These items can

usually be summed up for the year and properly

prorated to the various turnover periods.

Allowance is made for contingencies to offset

such items as shrinkage in quality during turnover, bad debts, unforeseen costs, extension of

turnover period, abnormally large inventories,

and reduced market values. It is suggested that

an amount equal to 50 percent of the figure for

conversion and marketing costs be allowed

these items, and that this amount be added to

the estimated figure for conversion and marketing costs.

Marketing

Small sawmills differ considerably in the type

of product they put on the market, and for this

reason their marketing techniques differ as

greatly.

In general, they may'be classified as (1) custom mills, (2) short-log or specialty mills, (3)

mills placing a semifinished product with finishing plants, (4) mills cutting for a local market,

and (5) mills putting a finished product on the

general market.

The major business of custom mills, either

permanent or mobile, is the sawing of relatively

small individual ownerships of logs into products consumed by the owner, at a fixed rate per

thousand board feet. Normal production is between 100,000 board feet and 1,500,000 board

feet per year.

Operators of custom mills get customers by

advertising in local newspapers, by fihng a

statement of services at the office of the county

agent, local U. S. Department of Agriculture

office, or State or extension forester," and by

canvassing farmers directly. Emphasis should

be given to collecting for each job at completion, and records should be kept of the customer's name, the date of completion, the time

charged, the amount of lumber or other products sawed, and the charge made.

Short-log or specialty mills cut a special

product, such as ties, rough-sawed blanks for

heel stock, shuttles, or spools, or box lumber.

They are selective as to species. Individual mills

usually sell the major product to a single outlet

and often contract production prior to manufacture. Customers are usually contacted directly and agreements reached on specifications,

conditions of delivery, volumes, price schedules.

" Periodical marketing bulletins are prepared in many

States by the State Forester at the State Capital, or

by the State Extension Forester at the agricultural

college.
106 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

terms of payment, and contract period. Each

party should have a written copy of the agreement, properly signed. The record for each consignment is kept by the mill operator as a

check against the buyer's tally; this record includes date, amounts by items, and price.

Mills placing a semifinished product with

finishing plants sell it unsurfaced and usually

ungraded, or in classifications requiring regrouping for yard and industrial outlets. The

operator usually sells directly to big sawmills,

planing mills, box manufacturers, and, in the

case of hardwoods, to wholesalers. Such an

operator can use immature and low-grade timber, streamlining his costs by concentrating on

a limited number of items that are in a semifinished, incompletely graded state and are sold

usually to a single buyer who provides a quick

turnover and prompt collections. Customers are

contacted directly and recording procedure is

similar to that described for specialty mills.

Mills placing a finished and semifinished

product on the local market cater to local business within the limits imposed by species suitability. The usual items are surfaced framing,

sheathing, subflooring, siding, interior finish,

flooring, and miscellaneous material used by local industries, farms, and communities. These

mills combine manufacturing and retailing and

can advantageously use timber of a broad range

of qualities.

Customers are reached through advertising

in local newspapers and through contacts with

building contractors, highway departments, local wood-using industries, county agents, and

farmers. This type of business requires complete accounting that covers, for each sale, the

date, the customer, the quantity and price by

items together with totals, the terms of payment, and, for each account, the charges and

payments made to date and the balance due.

Sales slips are made in duplicate for each consignment, one copy going to the buyer and the

other to the seller. This type of business should

follow a conservative policy in extending

credits.

Mills placing a finished product on the general market should have a production rate and

quality of timber that make practical the diversification of products by grades and patterns in

sufficient quantities to fill normal orders. Such

mills normally produce more than 3,000,000

board feet annually, and draw upon mature

timber. They sell directly to retailers, through

wholesalers and commission agents, and to industrial users. Complete accounting, as outlined

for mills serving local markets, is required;

credit terms commonly extended by well-managed mills usually are about as follows :

1. To retailers, 60 days net from date of invoice or 2 percent cash discount of net after

deducting freight, if paid within 10 days of car

arrival.

2. To wholesalers, 80 percent of net, minus

freight, within 15 days after date of invoice;

balance, less 2 percent of total net minus

freight, within 30 to 60 days of date of invoice.

3. To industrials and buyers not otherwise

classified, 60 days net from date of invoice, or

2 percent cash discount if paid within 10 days.

Discounts and commissions for distribution

service adhere to the following pattern : (a) To

wholesalers, discounts up to 8 percent on f.o.b.

mill ^price ; (b) to commission salesmen, discounts up to 5 percent on f.o.b. mill price.

When credit is extended the buyer gains possession of the lumber before he pays for it.

Therefore, the seller has the responsibility of

checking on the buyer as a credit risk. The

financial and moral integrity of local outlets can

be judged from the experience of business associates or banks, or through businessmen's

ratings; that of nonlocal outlets of perceptible

size and permanency can be ascertained from

credit-rating lists usually available at banks,

trade association offices, and large manufacturing corporations.

Accountiug

Operators lacking an accounting system are

likely to underestimate their actual costs, particularly in such items as depreciation, maintenance and repairs, interest on capital tied up

in their business, and taxes. Following is a

description of an accounting system which is

suggested as a pattern to meet the requirements of small-sawmill management. The records_ called for under this system show the essential details of expenditures, receipts, and inventories, reflect the status of individual accounts, furnish facts for use in connection with

the Fair Labor Standards Act of 1938, and permit segregation of costs and returns for income

tax purposes.^

_ The pattern suggested is reduced to the

simplest form necessary, and requires but a

single listing of all expenditures and receipts.

In the forms presented, the labor account is

segregated from other expenditures in order to

have this information available to meet the

Federal wage-hour requirements. Individual

operations may benefit from further separation

of special classes of items in the purchase led-

' See U. S. Dept. of Commerce, Bureau of Foreign

and Domestic Commerce, Industrial Series Bulletin

No. 20, "Establishing and Operating a Small Sawmill

Business for Additional Cash."
SMALL SAWMILL OPERATOR'S MANUAL .

SALES, RECEIPTS« ACCOUNTS RECEIVABUB FOR MONTH OF FEBRUARY 1960

107

1 t t II t t t 1

DatetName and address oft Item iNumbertPrioetTotal tiznounttDateiTMpaldtCíalas

t

soldt customer t t

• • • • • I

of 1 per « value 1 paid i « bal- i and

t * < • t >

t

t t txuiits tunit t of t % tanoe t dist

t

t

• • • • • • s

I 1 sale * t 1 1 counts

Z/6 « Q^>-Án^ ^o^

^sU^^c*

II 1 IIi^7,so*

ZÛ.ÛO0* jf.ao* 3eû.oo* 3S0.00* t 30.001

1 '

t \ ^^' 1

t

t

1

t

1

1 Monthly stmnnary 1 tiSû.OOÛt tiSOá.00 tlJ-OÛ. 00 t tlfióO^Ot 30.OO

FIGURE 129.—Sample sales-receipts

the end of the month, the unpaid

end balances and profit-and-loss s1

ledger sheet. A separate record is made for each account, and is balanced at

balance being brought forward as the first entry for the ensuing month. Year-

.atements will be simplified if a different colored ink or symbol is used for

equipment subject to depreciation and for purchases of timber, logs, and lumber.

ger, carrying as separate accounts such items

as timber and its products, interest, taxes, insurance, and rent.

Records of purchases and expenditures (fig.

129) and of sales and receipts (fig. 130) are entered currently and balanced monthly. A yearend balance is made between assets and liabilities, and the net profit or loss from the current

year's operation is computed.

A balance sheet is ordinarily made yearly in

small enterprises. The procedure is to balance

assets (cash, accounts receivable, timber, logs,

lumber, plant, and supplies) against liabilities

(debts owned by the business). By definition,

cash includes all cash, checks, and negotiable

notes on hand at the end of the year. Accounts

receivable include all collectible unpaid balances

owed by customers as shown on the December

31 records of sales, receipts, and accounts receivable. Uncollectible accounts are written off

and listed as bad debts for income tax purposes.

A year-end inventory is made of all timber,

logs, and lumber in stock, and a value allotted

them. This value should be either the cost or

the market value, whichever is lower. Yard inventories are simplified if the date, item, footage, and species are marked on the pile when it

is completed, for example, 1/12/50 - 4/4 No. 1

- 3,650 - Ash. Logs are inventoried by checking

their footage and computing their cost or value

after deducting expected transportation costs

for logs in the woods or in transit. Timber is

inventoried by estimating the footage and computing its cost or value.

For balance-sheet purposes, the plant consists of all buildings and equipment required

for the operation. Its value should be based on

material purchase price plus installation cost,

and apportioned over the remaining useful life

to the operation. Buildings in permanent operations are commonly discounted at the rate of

5 percent yearly (original cost divided by 20) ;

for temporary operations, the original cost is

divided by the expected life of the operation at

that site. Other equipment is discounted yearly

by a sum equal to the purchase cost divided by

the expected life. If the item outlasts its estimated life, no value is henceforth given ; if the

useful life falls short of the estimated life, the

undiscounted balance is subtracted from the

value of all equipment. The total sum of these

yearly discounts on equipment and plant is the
108 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

RBCORD OF H7HCHASS3 ASD FAXMENTS FOR MONTH OF JONE 1940

: Supplies - Services - Timber ' '

1 Personal

Í

account—

'amount with-

! drawn from '

business

Date : Name and address of

bought: supplier

: ItemX

!

!

;Price (Amount

: paid

:Date

¡paid

¡unpaid

! bal-

: cuice

:Date

6// : tir !

: > . .:,. ' " : - ;

• ... .- a

• , -I

: Î

IS. 00

!

. fz. où J

:

;

<

. Ih.oo

!

i,oo ¡

' ,

¡

»

i

- ,-

Í

FIGURE 130.—Sample sheet of purchases-payments ledger. At the end of the month, each account is balanced and

the unpaid balance entered as the first item for the succeeding month.

depreciation account required for income-tax

purposes.

Supplies, as distinguished from equipment,

are short-life items (less than a year), such as

stock feed, gas, oil, and small tools. For the

balance-sheet account, those carried into the

new year are given a value as of December 31.

Liabilities include all unpaid bills as of December 31, as shown in the December record of

purchases and payments.

The accounts carried to this point serve as

records of individual transactions between the

business, its creditors, and its debtors, and provide in the balance sheet a yearly statement

contrasting assets with liabilities. A further

analysis is necessary to determine the net profit

or loss over the year. The items and method of

making computations for Federal income-tax

purposes consist of the following:

1. Total receipts (accounts paid and receivable)

2. Labor

3. Materials and supplies

4. Merchandise bought for sale

5. Other costs

6. Plus inventory at beginning of year

7. Total of items 2 to 6

8. Less inventory at end of year (cost or market)

9. Net cost ' .

10. Salaries

11. Interest on business indebtedness

12. Taxes and insurance

13. Losses

14. Bad debts

15. Depreciation

16. Rent, repairs, etc.

17. Total (items 10 to 16)

18. Total deduction (item 9 plus item 17)

19. Net profit (or loss) (item 1 minus item 18)

Item 1, total receipts, includes all accounts

paid and payable for sales of current year as

shown in the total value of all sales over the

year as taken from monthly totals, after deducting total claims and discounts. Accounts

payable carried from the previous year (shown

on the January record of sales, receipts, and

accounts receivable for the current year) are

not included. Accounts payable at the end of

the current year for items sold within the year

are included. Item 2, labor, includes all wages

paid and payable for work performed within

the current year, taken from the payroll form

as the total-earnings summation. Unpaid wages

carried from the previous year are excluded.

Unpaid wages at the end of the current year

are included.
SMALL SAWMILL OPERATOR'S MANUAL 109

Under item 3, materials and supplies, are

included all purchases normally used up in a

year or less. Equipment normally used for more

than a year is excluded and accounted for under

item 15 (depreciation). Purchases of timber,

logs, and lumber are accounted for under item

4 (merchandise bought for sale). Materials and

supplies thus include all such items as feed, veterinary service, shoeing of animals, oil, gas,

files, bits for saws, and belt lacings. The total

cost is taken from the record of purchases and

payments.

Item 4, merchandise bought for sale, takes

in all purchases of timber, logs, and timber

products made during the year and shown in

the record of purchases and payments. Under

item 5, other costs, are included all exchange

charges on checks, abstracting and attorney's

fees, surveying expenses, and like costs.

Item 10, salaries, embraces all wage payments for regular employees not recorded in the

labor ledger (fig. 131) as shown in the record of

purchases and supplies (fig. 129). Item 11, interest on business indebtedness, covers interest

payments made during the current year on

money borrowed for conducting the business.

These are taken from records of purchases and

payments. Item 12, taxes and insurance, takes

in all Federal, State, and local taxes, social

benefit assessments, and insurance payments

assessed against the business during the current year, as shown on the Record of Purchases

Work week endlng_ _Date oí' payîT.ent (f)_

Kam

in full

: ;

• Social ;

: :

Hours worked Regular rate

of pay

: »läge s

:

: security: S

Î :*

:account :

: M

:

! T iV : T F S Total

Kami m's

:

• Deduction» Total

wages

iDn- I AdAt :¿Atrai Total FederaliOt'her tpaldi vancea

No. :

:

: rogular: for

:

rate of:over-

• earn- lold agei(iteiii-

! : :

• ings jinsur- lized)

paid ibal-i

lancei

-'.,

: pay for:time anoe :

: total : taxes :

: hours :

rtorked t •

(a) •Ad) (d) (d) (d) (d) id) (d) (d) (g) (h) (i) (e)

1. Jorm Henry

Dm

129-99- :...

4231 i

8 8 8 8 8 8 48 Ö1.55 per hr.

($1.60 per

$ 74.40 $6.20 3 80.60 $ 1.21 $ 79.39

; hr. plus 1 t

; : bonus)

2. Uartha Jane

Doe

164-S9- :...

2176 !

8 8 8 8 8 5 45 El.25 per hr,

($50.00

56.25 3.12 59,37 .89 58,48

: 1 per wk, of

: 40 hrs.) :

5. Henry John

Roe

356-99- :...

:

4578 :

:

8 8 8 8 8 7 47 $1.10 per hr.

($1.90.48 per

ito. on a Tik,

of 40 hrs.)

51.70 3.85 55.55 .83 54,72

4. Itary Beatrice 369-99- :... 8 8 10 8 8 i 8 50 $0.75 per hr. 37.60 3.75 41,26 .62 t : 40.63

Roe 7241 : Ï (tS7.S0 pu : :

I

:

!

Î

V*.) : :

: ' '

Total_ _»256.77 1233.22

FIGURE 131.—The sample payroll form of the Wage and Hour Division of the U. S. Department of Labor, shown

here, is, with minor additions, a convenient labor ledger. The "Employers' Digest of the Fair Labor Standards

Act of 1938" issued by that division interprets provisions denoted by letters in parentheses.

471449°—58 8 . ''
lio HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

and Payments. Any assessments included in the

payroll form are not repeated here.

Item 13 involves losses within the current

year not reimbursed by insurance to the property or stock from fire, flood, theft, and other

misfortune. These losses are given a value in

line with book values carried in the balancesheet inventory of assets. They are not to be

confused with item 14, bad debts, under which

is lumped all credits which are uncollectible and

eliminated from the assets in the balance-sheet

inventory of assets. Item 15, depreciation, represents the total sum of the yearly discounts on

equipment and plant (table 18).

TABLE 18.—Useful life of mill equipment and

tools as a basis for estimating depreciation

Item Expected

life

Yearly

depreciation

Horses

Mules ^

Sleds-_

Log wagons

Felling tools. _ . -

Yearx

5

5

5

5

1

4

4

4

(•)

3

20

20

10

15

10-12

10-12

10-12

10-12

4

5

5

l^ercenl

20

20

20

20

100

Truck (logging)

Cats - .

25

25

Tractors.. - 25

Shacks and buildings

Jammers

Mill building (permanent) ^_

Steam engines

Gas units

33^

5

5

10

Diesels 7

Edgers

Mill machinery

10

10

Trim saws

Rolls

10

10

Saws -

Lumber trucks

Lumber wasrons

25

20

20

1 Life of operation.

2 Temporary set-ups estimated on basis of life of operation.

Under item 16 are included all rents, payments for options and leases, and repairs on

equipment not recorded under item 3 (materials and supplies), and shown in the monthly

record of purchases and payments.

The method used on income-tax statements

to determine the net profit or loss is as follows :

To the sum of the costs of items 2, 3, 4, 5, 10,

11, 12, 13, 14, 15, and 16, add the value of the

inventory taken at the beginning of the year

and then subtract the value of the inventory

taken at the end of the year. This represents

the total costs of doing business for the year,

which are subtracted from the total receipts in

order to determine the total net profit or loss

for the year.

Total net profit or loss per thousand board

feet is found by dividing the year's net profit

or loss by the number of thousand board feet

sold during the year as given in the totals on

the record of sales-receipts-accounts receivable.

An accounting can be begun by making a

balance sheet of the business. The assets consist of (1) cash, checks, and negotiable paper

on hand, (2) accounts receivable, (3) the value

of timber, logs, and lumber in stock, and (4)

the value of plant and supplies. The liabilities

include all unpaid bills and obligations.

Enough space should be allowed in the purchases-payments and in the sales-receipts ledgers for entering under an individual account

all probable purchases during the month. At the

end of the month each individual account is

balanced on both ledgers, and unpaid balances

are entered as first items of these accounts for

the succeeding month. A sheet is reserved for

monthly summaries going to make up the yearend balance sheet and profit-or-loss statement,

and for filling in the totals for the month for

the headings suggested on the lower part of the

purchases-and-payments form and on the salesreceipts-accounts-receivable form.

Public Regulations Affecting Sawmills

Sawmill operators are subject to specific Federal, State, and local regulations. The subjects

covered by regulations affecting a sawmill operation usually include those following.

1. Safeguards of the health and working conditions

of employees. These include provisions on sanitation of

drinking water and toilet facilities, and details of

spacing from wall to mill carriage, guards for saws

and belts, and construction requirements and safety

devices for boilers.

2. Measures designed to minimize community or

commonwealth hazards; for example, control over

stream pollution and refuse disposal, zoning ordinances, and fire-prevention measures.

3. Child-labor provisions.

4. Social-security taxes applying to employees on a

national and, in some cases, a state basis. Each employee must have a social-security number. The assessments are for unemployment and old-age insurance.

5. Sales and excise taxes. Federal or state taxes in

this category may consist of special taxes carrying

over from war emergency measures, such as the Federal tax on freight bills, or more permanent tax measures, including state and city sales taxes and tonmile tariffs on intrastate motor trucking.

6. Wage-hour regulations. Federal and, in some instances, state laws prescribe the maximum number of

hours employees can be worked per day or week and

the minimum hourly wage that can be paid.

7. License to do business. Such a license is required by some states.

The above list is not all-inclusive. Federal

regulations apply to mills in all states. State

regulations vary in scope among the different

states. A mill operator should determine the

rules and regulations of Federal, state, and

local agencies which affect his business. Fed-
SMALL SAWMILL OPERATOR'S MANUAL 111

eral regulations included under the seven

groups listed should be requested from the

U. S. Department of Labor, Division of Labor

Standards, Washington, D. C. ; state regulations from the Secretary of State of the state

in which the mill is located; and those of

municipal units from the mayor's office.

Aside from the regulatory aspects, it is to

the employer's interest to promote safety measures. It is practical for all mills to foster a

consciousness of hazards on the part of workers. This can be done in the course of job training by talks emphasizing safety measures, and

displaying posters and other literature published by equipment manufacturers where employees will see them.

The degree of permanency of the mill greatly

influences how much can be done in the installation of guards for moving parts. Virtually all

mills can install a barrier between the headsaw

and the sawyer to deflect chips and fine particles. A wire screen (i/^-inch mesh) is adequate.

Areas occupied by workmen should have

floors cleared of trash or obstacles and leveled ;

if planked, they should be free of loose parts

or holes.

The top portion of swing saws which cut below the arbor should be enclosed in a guard and

the frame equipped with a chain limiting the

arc of pull. In less temporary sets, guards can

be installed to prevent workers from contacting

moving parts. Belts can be fenced off and posts

or other barriers placed to prevent injury when

flat belts break. Shafting, pulleys, gears, and

similar revolving members should be enclosed

to a maximum degree.

When repairs or adjustments are necessary

the rotating members should be stopped. Set

screws or comparable projections on a revolving

member are a particularly dangerous source of

accidents and should be guarded or screened

from contact with workmen.

The tail sawyer should wear goggles, and all

men piling or transferring material should

wear heavy aprons.

Insurance

Two types of insurance are available to the

sawmill owner, that which protects him against

property loss and that which covers liability

claims. Fire-insurance rates are relatively high

for sawmills and lumber yards. Fire losses are

the dominant type of disaster, but insurance

may also be had against wind and cyclone

losses. Liability insurance is commonly carried

on trucks and automobiles to protect the owner

when claims result from accidents.

SCALING AND GRADING LOGS

Logs are usually valued on the basis of quantity as interpreted by a log scale and quality as

interpreted by a log grade.

Log Scaling

A number of log scales are in use. Scaling

consists of noting, on the log rule, the quantity

of material in a sound, straight log of the given

length and average diameter inside the bark,

and making deductions for the estimated

amounts by which crook, shake, decay, and

other defects lessen the quantity of material recoverable from the actual log being scaled.

Most log rules have been so constructed that

they apply to average diameter at the small end

to the nearest inch. The waste in a defective

log can be computed with accuracy if its boundaries are known. The boundaries of internal

defects must usually be guessed, and knowledge

of the characteristics of rot, shake, and similar

defects is vital to accurate work. This knowledge is best acquired by checking at the mill

as to actual yields of merchantable material

sawed from defective logs. The full scale minus

the amount computed for defects gives the

computed merchantable scale of the defective

log. The details of waste computation may vary

with the different log scales and other factors.

The Forest Service instructions for scaling

with the Scribner Decimal C rule indicate that

the amount computed for defects is usually regarded as four-fifths the squared-up portion

that must be sawed out to eliminate the defect,

an allowance of one-fourth inch for saw kerf

being made for each inch board. The amount

can therefore be found by multiplying the

width by the height of this squared portion in

inches, and that product by the length in feet,

dividing the final product by 15.

For internal defects, such as hollows, rots,

shake, and cracks, an allowance of 1 inch is

customarily added to both their height and

width. Where a defect is visible on both ends

of the log, the larger visible area is used in

computations; if it is visible only on one end,

the length of the defect is estimated.

For external defects, such as fire scars, the

only portion considered is that which is not
112 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

slabbed off when the saw is started an inch inside the bark at the small end and sawing is

done parallel to the axis of the log. In computing the affected portion of the log, the

greatest depth, average width, and total length

of the defect are used.

For crooked logs, it is customary to assess a

length penalty sufficient to compensate for the

waste. Thus, a 16-foot log may be scaled as a

14-foot, or even a 12-foot log, of similar diameter. The beginner can check this estimate

as follows.

Estimate the length of the straight section.

If the crook is nearer the top end, the waste becomes a portion of four-fifths of a squared piece

with a depth corresponding to the distance the

crook distorts the end of the log from straightness; that is, the distance from the top inside

bark of the straight section of the log to the

top inside bark of the crooked section (fig. 132,

A, line a—b) ; the length is the number of feet

to the crook (line a—c) ; the width is the average in inches of a slab face starting an inch

inside the bark at the end of the crooked section and extending through the crooked section

on a plane parallel to the axis of the straight

section.

If the crook is nearer the bottom end, the

depth of the squared-up portion is the distance

in inches from a line parallel to the axis of a

straight log, starting an inch inside the bark

at the top, to an inch inside the bark at the

lower end (fig. 132, B, line a—b) ; the length is

the distance in feet back to the crook (line

a—c) ; the width in inches is the average face

width of the cut from an inch inside the bark at

the lower end back through the crook, taken

FIGURE 132.—Method of deducting for crook in scaling

crooked logs. A, Crook near top end; B, crook near

bottom end.

parallel to the axis of the straight section (line

b—d). Since some of this square piece can be

recovered, the sealer must estimate the portion

lost (one-half, one-third, or more of four-fifths

the volume of the squared piece) and subtract

this from the scale of a straight log. The reduction in length that gives the nearest comparable

scale is used in reducing the length when proficiency is attained.

Log Grading

The practice of purchasing and selling logs

on a log-grade basis is gaining acceptance because prices can be correlated to the variability

between logs in value per unit of product. By

such grades, logs are usually segregated according to quality into high, medium, and low

classes, each showing a substantial differential

in average lumber values. Log grading, like

scaling, requires individual log examination but

should decrease the risk of incorrect appraisals.

The buying and selling of logs on a log-grade

basis has resulted in the use of many log-grade

specifications. Some standardization has been

reached in the case of black walnut and for several species of the Pacific Northwest. Specifications relating to black walnut are promulgated

by the American Walnut Manufacturers' Association, 616 S. Michigan Avenue. Chicago 5,

111. Those relating to Douglas-fir, Sitka spruce,

western hemlock, noble fir, Port Orford whitecedar, western white pine, and silver and white

fir are issued by the Columbia River Log Scaling and Grading Bureau, 708 U. S. Bank Building, Portland 4, Oreg. ; Puget Sound Log Scaling and Grading Bureau, 4459 Stuart Building,

Seattle, Wash. ; and Grays Harbor Log Scaling

and Grading Bureau, Finch Building, Aberdeen,

Wash.

Descriptions and discussion of defects that

may affect the grade of hardwood logs of some

species will be found in U. S. Department of

Agriculture Handbook No. 4, "Log Defects in

Southern Hardwoods" (for sale by Superintendent of Documents, Washington, D. C, at

25c a copy).

Specifications that have gained considerable

acceptance as applying to hardwoods are described in Report No. D1737-A, "Hardwood Log

Grades for Standard Lumber and How to Apply

Them," issued by the U. S. Forest Products

Laboratory, Madison 5, Wis. Specifications for

eastern softwood species have not thus far received so much recognition as those for other

kinds mentioned here. However, experimental

work is underway on certain of the eastern and

southern softwoods. Pending the development

of better log-grade specifications, those currently available are given in table 19.
SMALL SAWMILL OPERATOR'S MANUAL

TABLE 19.—Log-grade specifications for some eastern softwood species

113

Log

grade

Minimum sizes Maximum

Species defect Surface requirements on visible faces

Diameter Length permitted

Inches Feet Percent

Eastern white pine_ 1 13 + 8 + 10 Surface clear.

1 13 + 10 + 30 Must be 50 percent clear in cuttings at least 8 feet long or one face

clear full ength.

2 9 + 10 + 30 Sound, tight knots not larger than 2J^ inches in diameter. Occasional larger knots permitted if others are not larger than 2

inches.

2 17 + 8 + 40 Tight knots not over 3 inches in diameter. Occasional larger knots

permitted if others are tight and not over 2J^ inches in diameter.

3 6 + 8+ 50 Any log below No. 2 generally sawed. Logs with knots 4 inches

or more in diameter in whorls less than 2 feet apart not accepted

unless }4 full length has knots 2 inches or less in diameter.

Spruce and balsam _ 1 8 + 12 + 20 Sound, tight knots not over 2 inches in diameter or in whorls not

closer together than 2 feet.

2 8 + 10 + 50 Sound, tight knots not over 3 inches in diameter in whorls not

closer together than 2 feet unless }4 full length has knots only

2 inches m diameter.

Eastern hemlocks _. 1 8 + 10 + 25 Sound, tight knots not over 2J^ inches in diameter or in groups

not less than 2 feet apart. Shake not over 15 percent of gross

scale.

2 8 + 10 + 50 Sound knots; no size limitation. Shake not over 25 percent gross

scale. Logs generally sawed for lumber.

Red pine 1 13 + 8 + 10 Surface clear; no shake.

13 + 10 + 20 Must be at least 50 percent clear in cuttings 8 feet or longer, or

clear one face for full length. No shake.

2 9 + 10 + 30 Sound, tight knots not over 2J^ inches in diameter. Occasional

larger knots if other knots not over 2 inches in diameter.

2 17 + 10 + 40 Sound, tight knots not over 3 inches in diameter. Occasional

larger knots if other knots not over 2}^ inches in diameter.

3 8 + 10 + 50 Any log below No. 2 generally sawed. Logs with knots 4 inches

or more in diameter in whorls less than 2 feet apart not accepted

unless i4 full length has knots 2 inches or less in diameter.

Southern yellow

pine 1 12-15 12 + 20 Clear. No knots or indications of knots.

1 16 + 12 + 30 Two clear faces or 75 percent of 3 faces clear in one piece.

2 10-14 12 + 40 Sound, tight knots not more than IJ^ inches in diameter.

2 15 + 12 + 50 Sound, tight knots not more than 2J^ inches in diameter.

3 8 + 12 + 50 Any log below No. 2 that is generallj' utilized.

ORGANIZATIONS ISSUING GRADING RULES

standard grading rules for lumber can be

secured from the following sources:

For southern yellow pine—Southern Pine Association, New Orleans, La.

Eastern white pine, red pine, eastern spruce, tamarack—Northern Pine Manufacturers Association,

Minneapolis, Minn., or Northeastern Lumberman's Association, New York, N. Y.

Baldcypress—Southern Cypress Manufacturers Association, Jacksonville, Fla., or National Hardwood

Lumber Association, Chicago, 111.

Douglas-fir, western hemlock, Sitka spruce, western

redcedar — West Coast Lumbermen's Association,

Portland, Oreg.

Ponderosa pine, western white pine, sugar pine,

western larch, white fir, Douglas-fir, California incensecedar, and spruce—Western Pine Manufacturers Association, Portland, Oreg.

California redwood—Redwood Association, San

Francisco, Calif.

Eastern hemlock and tamarack—Northern Hardwood and Hemlock Association, Oshkosh, Wis.

Hardwoods and eastern redcedar—National Hardwood Association, Chicago 5, 111.
GLOSSARY

Adventitious buds.—Abnormal groups of buds found at

points on the stem unrelated to the crown.

Air drying.—The practice of seasoning lumber in the

open air as contrasted with seasoning it in a kiln.

Alligator fastenings.—Metal belt fastenings that can

be attached to a belt end by means of barbs and to

each other with a key inserted in a sleeve resulting

from intermeshed dentated parts.

Anvil (swage).—The fixed jaw in a swaging device

that supports the back of the tooth while the die or

roller presses against the front of the tooth.

Arbor.—The shaft and bearings on which a circular

saw is mounted.

Back rest.—A wood bench opposite the tensioner, used

to support a circular saw when checking tension.

Band saw.—An endless beltlike blade of steel, toothed

on one or both edges, which is used to saw lumber.

Barb.—A sharp projection, the point of which is at

right angles to the fastener proper.

Bearings.—A part in which the journal, gudgeon,

pivot, pin, or the like, turns or revolves.

Blue stain.—A bluish or grayish discoloration of sapwood caused by the growth of certain moldlike fungi

on the surface and in the interior of the piece; made

' possible by the same conditions that favor the growth

of other fungi.

Boards.—See Lumber.

Board foot.—A unit of measure in the lumber trade.

A board foot is a section 12 by 12 inches in size and

1 inch thick.

Board mill.—-A sawmill that makes a specialty of 1-

and 2-inch lumber as compared to a mill that makes

a specialty of material of greater thickness.

Bolster.—A structural part intended to afford support

for logs on a sawmill carriage.

Boss dog.—A dogging device on the knees of a sawmill

carriage consisting of lever-controlled talons which

can be brought to grip the face of a log, cant, or

timber.

Boxed heart.—The term used when the pith falls entirely within the four faces anjrwhere in the sides of

the length of a piece.

Box lumber.—Lumber from which boxes are manufactured.

Box piling.—A method used in piling lumber for drying by which boards of differing widths and lengths

make up a course.

Bulk pile.—To pile closely, without cross strips.

Bummer.—A low, two-wheeled truck for skidding logs.

Bunk.—The cross beam on a log car or sled, upon which

the logs rest.

Burl.—A large, wartlike excrescence growing on a tree

trunk. It contains the dark piths of a large number

of buds which rarely develop. The formation of a

burl apparently results from an injury to the tree.

Burner.—An open or enclosed structure in which slabs,

sawdust, bark, and other sawmill wood refuse are

burned.

Canker.—A pronounced, local distortion of the stem

due to injury or disease, in advanced stages evidence

of serious heart rot.

Cant.—A log that has been slabbed on one or more

sides.

Cant hook.—A tool like a peavy, but having a toe ring

and lip at the end instead of a spike. See Peavy.

Carriage.—A frame on which are mounted the headblocks, setworks, and other mechanisms for holding

a log while it is being sawed, and also for advancing

the log toward the saw line after a cut has been

made. The carriage frame is mounted on trucks

which travel on tracks, the carriage being actuated

by a steam feed, a cable, or a rack-and-pinion device,

which propels it back and forth past the headsaw.

Centrifugal force.—The force which impels a thing, or

parts of a thing, outward from a center of rotation.

Check.—A lengthwise separation of the wood, the

greater part of which occurs across the rings of

annual growth.

Chip.—The shaving or segment taken by a single sawtooth.

Chucks.—Any of the various contrivances for holding

work or a tool in a machine.

Circular headsaw.—A circular plate having cutting

teeth on the circumference and used to ripsaw logs.

Clearance angle.—The angle between a tangent to the

cutting circle of a tooth and a line along the top of

the tooth intersecting this tangent.

Clear face.—1. In cutting hardwoods, board surface

area free from defects recognized in grading hardwood lumber. 2. In a log, quadrant of log surface

without blemishes indicative of causing defects in

lumber.

Clipper fastening.—A belt fastening installed by a

special tool (belt lacer) and consisting of a series of

wires, each making a loop around a metal core, and

the two hooked ends embedded in the belt end, with

adjacent units attached to opposite belt ends.

Clutch.—A coupling for connecting two working parts,

permitting either to be thrown at will into or out of

gear with the other, as by moving a lever.

Collar.—A ring or round flange upon, surrounding, or

against an object and used chiefly to restrain motion

within given limits, to hold something in place, or to

cover an opening.

Commission agent.—One who undertakes to sell prodducts on a commission basis.

Conveyor chain.—An endless chain used for carrying

material from place to place.

Conical roller bearings.—Roller bearings with tapered

rollers.

Conk.—The fruiting body of a rot-producing fungus

contained in the tree.

Course.—A single layer of boards in a pile of lumber.

Crib piling.—^Piling lumber to form a triangular pen

with the end of a board overlapping the end of the

board below. Usually each side is a single tier.

Crook.—See Sweep.

Cross alleys.—Alleys in the lumber yard at- right

angles to main alleys to facilitate lumber movement

and air flow.

Custom sawing.—The sawing of lumber under contract,

usually to given specifications.

Cutting face.—That part of a sawtooth which extends

from the point or edge down toward the gullet, a

distance equal to that where cutting or shearing of

fibers is done.

Cutting.—In hardwood lumber a cutting is a portion

made by imaginary ripping, by crosscutting, or by

both.

Dead rolls.—Rollers used for the handling of lumber,

but not power-driven.

Decay.—Disintegration of wood substance through the

action of wood-destroying fungi.

Deck.—The platform in a sawmill on which logs are

collected and stored before they are placed on the

carriage for sawing.

Deckman.—In a sawmill, one who alines logs on the

deck and rolls them down for loading on the carriage.

Deck skids.—Sets of timbers used to form a rollway for

logs at the mill deck.

Defect.—Any irregularity occurring in or on wood

that may lower its strength.

114
SMALL SAWMILL OPERATOR'S MANUAL 115

Die (swage).—One of a pair of shaping tools, which,

when moved toward each other, produce a certain

desired form in an object. In a swage tool the die is

the movable part, the anvil the fixed part of the

shaper.

Dimension.—All yard lumber except boards, strips, and

timbers; that is, yard lumber 2 inches and under 5

inches thick and of any width.

Dock.—An elevated structure at the rear of a sawmill

on which sawed products are stored and from which

they can be loaded on cars or ships by gravity.

Dog.—A steel, toothlike projection that is attached to

a carriage knee and usually operated by a lever.

Carriage dogs are used to hold the log firmly on the

carriage.

Dog board.—In sawing lumber on a headsaw, the last

board in the log to which the carriage dogs are

attached.

Dogging.—Process of fixing the dogs in the wood or

releasing them from it.

Dog housing.—The metal frame sheltering and supporting the dog.

Dolly.—A two-wheeled truck for transporting lumber

around a sawmill plant and yard.

Double-acting setworks.—A device on the carriage of a

sawmill which feeds the timber to be sawed transversely at both the thrust and return stroke of the

activating lever.

Double bed.—The metal member supporting the slab or

flitch being sawn. It is divided into two parts each of

which can be independently set at a desired distance

from the saw.

Double sheave.—A pulley block with two grooved

wheels.

Down-graded.—Placed in a lower grade.

Dressed ¿MTO& er.—Lumber that has been dressed or surfaced on one or more sides.

Drive pulley.—The first of a train of wheels, giving

motion to the rest.

Drum.—A revolving cylinder upon which the cable

imparting motion to the carriage is wound or unwound.

Dump log.—A mill platform on which logs are unloaded from log cars. It may be built around the

edge of a pond or along the bank of a stream to aid

in dumping logs into water, or it may be so built for

use as a place for dry storage of logs.

Dump ramp.—The platform and incline from which

logs are unloaded.

Dutch oven.—An extension front used with boilers

burning sawdust and similar fuel. It provides greater

fuel space and permits more complete combustion.

Eccentric.—Not having a true center.

Edge.—To make square-edged.

Edgings.—Strips, usually discarded or burned as fuel,

that are cut from the edges of boards.

Edger.—A machine used in sawmills to square-edge

wavy lumber and also to rip lumber. It consists of a

frame suporting an arbor on which are mounted one

to several circular saws, and may have feed rolls,

press rolls, and transmission gear.

End pile.—Comparable to an up-ended flat pile.

End rack.—Lumber edge-tilted against a ridgepole to

form an inverted V.

Eye (saw).—The hole through the center of the saw

which receives the shaft.

Face (log).—A quadrant of the surface of a log.

Fake knees.—See Taper bars.

Feed.—In sawing lumber the linear length of log, expressed in inches, which is cut at each revolution of

the saw.

Feed tuorks.—The mechanism which moves the carriage

past the saw.

Filer.—One who fits saws in a sawmill or other woodworking plant.

Fixed collar.—A collar firmly attached to the saw

arbor, as distinguished from a loose collar, which is

held to the arbor with a nut.

Fixed post.—A bar or rod firmly fixed to the knee or

log beam of a sawmill carriage, which supports all

or part of the dog mechanism.

Flat pile.—Lumber piled so that each piece rests on its

wide face.

Flexible coupling.—A coupling of jointed links placed

in a shaft to allow slight misalinement between two

connected shafts.

Flitch.—A thick piece of lumber with wane on one or

both edges.

Floating block.—A block to hold down the log against

conveyor chains, one end being pivoted above the

conveyed logs by means of a shaft and the other free

to float or move up and down in bearing on the top of

the moving log.

Flooring.—Patterned lumber used for floors.

Footage.—Quantity of lumber expressed in board feet.

Friction wheel.—A wheel or disk driving or driven by

direct contact with another wheel or disk.

Gage.—A standard series of sizes indicating by numbers the thickness to which saws are made. The particular series of sizes adopted by saw manufacturers

is the Birmingham wire-gage one.

Gang circular.—A machine having a battery of circular saws, from 22 to 26 inches in diameter, all of

which are fitted to the same shaft.

Gate.—The frame in which gang saws and sash saws

are stretched. The frame moves up and down in

vertical grooves or slides, and is actuated by a pitman attached to its base.

Gig.—The act of running the sawmill carriage back

after a board is cut from the log.

Grade.—The designation of the quality of a manufactured piece of wood.

Green.—Unseasoned, wet.

Ground mill.—A small sawmill placed directly upon the

g:round—unfloored.

Guide (saw).—A device for steadying a saw.

Growth ring.—See Ring, growth.

Guides (dip-tank chains).—Metal channels in which

conveyor chains run.

Guide blocks.—Arms of the saw-guide mechanism

which hold the guide pins.

Guide bracket.—Frame supporting the saw-guide pins.

Guide pins.—Parts of the saw-guide mechanism which

actually contact the saw.

Guide plates.—Metal plates fixed to synchronize with

the kerf at the rear of the saw.

Guide rail.—A rail that guides the movement of the

sawmill carriage.

Gullet.—On a saw, the rounded cavity in which sawdust accumulates and is carried from the cut.

Gumming,—The process of cutting out the gullets of a

saw.

Hammer bench.—A wood bench as an extension of the

anvil opposite the tensioner's position and supporting the rim of the saw when testing for tension; it

contains a peg on a sliding panel for centering the

saw when it is hammered.

Hardwoods.—The botanical group of trees that are

broadleaved. The term has no reference to the actual

hardness of the wood. Angiosperms is the botanical

name for hardwoods.

Headblock.—That portion of a sawmill carriage on

which the log rests. Each headblock consists of a

base, a knee, a taper set, dogs, and a rack-andpinion gear, or some similar device for advancing

the knees toward or withdrawing them from the

saw _ line.

Headrig.—Sawing equipment used in the primary

breakdown of logs.

High-speed teeth.—Sawteeth made of an alloy steel
116 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

which is heat-treated and retains much of its hardness and toughness at red heat, thus enabling tools

made from it to cut at such speeds that they become

red through friction.

Holder (sawtooth).—A device for locking inserted sawteeth in a circular saw.

Hollow ground.—Having concave surfaces.

Honeycomb.—Checks, often not visible at the surface,

that occur in the interior of a piece, usually along

the wood rays.

Hook.—The angle between the face of a sawtooth and

a line drawn from the extreme point of the tooth

perpendicularly to the back of a handsaw, or to the

center of a circular saw.

Hopper,—A receptacle, usually funnel-shaped, with an

opening at the lower part for delivering material.

Horizontal resaw.—A band resaw that cuts in a horizontal line, as compared to a vertical band resaw,

which cuts in a vertical line.

Husk.—The frame supporting the arbor and other

working parts of a circular headsaw.

Infeed rolls.—Rolls placed ahead of certain types of

saws to force the material through the saw.

Inserted point.—The tooth used in an inserted-tooth

saw.

Interior finish.—Dressed and often patterned lumber

used for finishing the interior of buildings.

Jacklq^dder.—An inclined plane with a trough up which

logs are drawn into a sawmill.

Jointing.—The act of reducing points of all teeth in a

circular saw to coincide with the circumference of a

circle when the saw is rotated; it is accomplished by

abrasion.

Kerf.—The width of cut made by a saw.

Key.—A small, parallel-sided piece, flat or tapered on

top, for securing pulleys and other parts to shafts.

Keyway.—A groove or channel for a key, as in a shaft

or the hub of a pulley. A keyseat.

Kiln.—A heated chamber for drying lumber.

Kiln drying.—The process of drying wood in a kiln

with the use of artificial heat.

Knee.—The part of a sawmill carriage headblock that

bears the carriage dogs, which hold the log being

sawed. It also supports the levers used to operate

both the carriage dogs and the taper set.

Knot.—That portion of a branch or limb which has become incorporated in the body of a tree.

Lead.—Adjustment of the saw so that the distance to

the track rail is slightly less at the front than at the

back edge of the saw.

Left-hand blower.—A blower in which, viewed when

standing on the log deck and facing the rear of the

mill, the fan-drive pulley is on the right and the

intake on the left side of the housing.

Left-hand sawmill.—A sawmill in which the carriage

and saw are on the left-hand side of a person standing on the log deck and facing the rear of the mill.

Leveling.—Act of bringing a saw to a fiat, even surface.

Lever-type swage.—Device for widening the tips of

sawteeth by drawing out the tooth point between a

lever-actuated die and a fixed anvil.

Log-beam mill.—The type of mill employing a sawmill

carriage on which the knees, dogs, and sometimes

the setworks, are fixed to a movable beam extending

lengthwise of the carriage frame, and advanced or

receded by a setworks mechanism.

Log dog.—A metal bracket attached at intervals to the

log-haul chain to prevent slippage in logs being

transported from log pond or yard level to mill deck.

Logging.—The operations of felling trees, cutting

them into logs, and transporting them to the sawmill.

Log rule.—A table showing the estimated number of

board feet of lumber that can be sawed from logs

of various lengths and diameters.

Log scale.—The board-foot content of logs as determined by a log rule.

Log turner.—A device, usually attached to beams over

the log deck, consisting of a drum driven by friction

gearing, on which is wound a chain or cable; used

in turning logs on a sawmill carriage. A device

actuated by a steam piston and consisting of two or

more arms or skids and a hook, which are used to

shove or turn logs on a sawmill carriage. Its movements are controlled by the sawyer.

Loose collar.—The flanged collar that is fixed against

the circular saw by attachment to the arbor by

means of a nut.

Lug.—A projection, as on a chain, by which anything

is supported or carried.

Lug pin.—A metal pin chambered in the fixed and loose

collars and passing through a pin hole in the saw

to prevent the saw from slipping on the shaft.

Lumber.—The product of the saw and planing mill not

further manufactured than by sawing, resawing,

and passing lengthwise through a standard planing machine, cross-cut to length and worked.

Boards.—Yard lumber less than 2 inches thick, 8

inches or more in width.

Dimension.—All yard lumber except boards, strips,

and timbers; that is, yard lumber 2 inches and

less than 5 inches thick, and of any width.

Dressed size.—The dimensions of lumber after

shrinking from the green dimension and planing;

usually % inch less than the nominal or rough

size; for example, a 2 by 4 stud actually measures

1% by 3% inches. (See Lumber, Nominal size.)

Factory and shop lumber.—Lumber intended to be

cut up for use in further manufacture. It is graded

on the basis of the percentage of the area which

will produce a limited number of cuttings of a

specified, or a given minimum, size and quality.

Matched lumber.—Lumber that is edge-dressed and

shaped (worked) to make a close tongue-andgroove joint at the edges or ends when laid edge

to edge or end to end.

Nominal size.—As applied to timber or lumber, the

rough-sawn commercial size by which it is known

and sold in the market. (See Lumber, Dressed

size.)

Plank.—A broad board, usually more than 1 inch

thick, laid with its wide dimension horizontal and

used as a bearing surface.

Rough lumber.—Lumber as it comes from the saw.

Shiplapped lumber.—Lumber that is edge-dressed to

make a close rabbeted or lapped joint.

Strips.—Yard lumber less than 2 inches thick and

less than 8 inches wide.

Surfaced lumber.—Lumber that is dressed by running it through a planer.

Yard lumber.—Lumber that is less than 5 inches in

thickness and is intended for general building

purposes.

Lumber scale rule.—A rule indicating the number of

surface feet contained in boards of various widths

and lengths.

Magnetic brake.—A friction brake controlled by means

of a solenoid.

Main alley.—A lumber-yard alley on which lumber

piles front.

Mandrel.—See Arbor.

Millwork.—Generally all building materials made of

finished wood and manufactured in millwork plants

and planing mills, excluding flooring, ceiling and

siding.

Mine detector.—An electrical device for detecting the

presence of metal.

Miscut.—Lumber having greater variation in thickness, except as to wane, between any two points than

provided for in copyrighted editions of association

grading rules.
SMALL SAWMILL OPERATOR'S MANUAL 117

Moisture content of wood.—Weight of the water contained in the wood; usually expressed in percentage

of the weight of the oven-dry wood.

Offsetting the carriage.—The shunting of the carriage

frame away from the sawline when the carriage is

gigged back by a device attached to a sawmill carriage frame and also to one or more axles of the

carriage trucks.

Offset (Knee).—See Taper bar.

Oil motor.—A rotary engine actuated by the reaction,

under pressurized oil, of radial pistons on a shaft

eccentric to a containing ring.

Overlap.—In a belt splice, the part extending over

another part.

Patterned.—Following a mechanical design.

Pawl.—A pivoted tongue or sliding bolt on one part of

a machine adapted to fall into notches or interdental

spaces on another part.

Peavy.—A stout lever from 5 to 7 feet long, fitted at

the larger end with a metal socket and spike and a

curved steel hook that is pivoted on a bolt. Diifers

from a cant hook in having a pike instead of a toe

ring and lip at the end.

Pinion wheel.—A gear with teeth designed to mesh

with those of a larger wheel or with a rack.

Pitch diameter.—In belt measurements, the diameter

at the outside of the belt minus the belt thickness.

Pitman.—A connecting rod.

Plain sawed.—Lumber sawed parallel with the pith of

the log and approximately tangent to the growth

rings; that is, the rings form an angle of less than

45° with the surface of the piece.

Planetary gears.—A train of spur or bevel gears in

which one or more move around the circumference

of another which may be fixed or moving.

Pond slip.—The extension of a mill pond to allow floating of logs to a point opposite the mill dock.

Poor face.—That surface of the board containing the

lesser area in clear cuttings.

Prime mover.—The initial source of motive power, the

object of which is to receive and modify force and

motion as supplied from some natural source, and

apply them to drive other machinery.

Rack.—A bar with teeth on one face for gearing with

those of a pinion.

Rack and pinion.—A form of carriage drive used in

portable sawmills. A rack is attached to the underside Of one of the beams of the carriage frame, and

into it meshes a pinion wheel driven from a shaft on

the saw husk.

Random, width.—All widths of lumber haphazardly

mixed.

Refuse conveyor.—An endless chain traveling in a

trough which transports sawmill refuse.

Resaw.—A machine to cut boards, planks, slabs, or

other material lengthwise into two or more pieces of

equal length and width.

Rider.—A pulley placed to bring pressure on a belt in

order to increase its effectiveness.

Right-hand mill.—A sawmill in which the saw and carriage are on the right-hand side of a person standing

on the log deck and facing the rear of the mill.

Rip.—To cut a board lengthwise, parallel to the fibers.

Rip tooth.—The type of sawtooth adapted for cutting

parallel to the fibers of wood.

Roller.—A cylindrical body movable about its longitudinal axis.

Rope drive.—A carriage feed system employing a rope

or wire cable to propel the carriage when a drum,

about which the cable is looped, is revolved.

Rosser,—An attachment to plane a flat surface on á

log.

Rot.—See Decay.

Round-faced hammer.—A type of hammer used to flatten the surface and put tension in circular saws. It

has a circular face with a convex plane, the curvature conforming to a radius of 4% inches.

Running board.—The board of the hammer bench extending back from the anvil, which partially supports

the saw.

Sap.—All the fluids in a tree, such special secretions

and excretions as gum excepted.

Sapwood.—The layers of wood next to the bark, usually

lighter in color than the heartwood and totaling %

to 3 or more inches wide, that are actively involved

in the life processes of the tree.

Seasoning.—Removing moisture from green wood in

order to improve its serviceability.

Setshaft.—The shaft on a sawmill carriage to which

the pinions are fastened and which causes the knees

to advance or recede as it is turned.

Setting.—The process of advancing the log on the carriage the distance required to get the sawed thickness desired.

Set wheel.—The wheel of the setworks attached to the

setshaft, which, when turned with a lever, causes the

knees to advance.

Shake.—A separation along the grain, the greater part

of which occurs between the rings of annual growth.

Shank.—A device for locking inserted teeth in a circular saw.

Shaper.—An implement, consisting of dies and levers,

which is used to compress sawteeth to a prescribed

pattern.

Sheathing.—The structural covering, usually of boards

or wallboards, placed over exterior studs or rafters

of a structure.

Sheave.—The grooved wheel of a pulley.

Shim (bearings).—A thin piece or slip of metal, wood,

or other material used to fill in, as in leveling.

Shipping-dry lumber.—Lumber that has been partially

dried to reduce weight and freight costs, but may

still have a moisture content of 30 percent or more.

Shotgun feed.—A long cylinder with a piston attached

to the rear end of the sawmill carriage to draw the

carriage back and forth.

Shoulder.—An abrupt projection that forms an abutment on an object or limits motion.

Side dressing.—The act of adjusting all sawteeth on a

saw to project laterally the same distance from the

plate. It is accomplished by filing.

Side gage.—A measuring device to indicate the amount

of lateral projection of sawteeth beyond the surface

of the saw.

Siding.—Material manufactured for the special function of serving as outside covering for buildings.

Sills.—The horizontal timbers supporting the husk of

a sawmill.

Single-acting lever.—A device on the carriage of a

sawmill which feeds the timber to be sawed transversely at the thrust or the return stroke of the

lever, but not at both strokes.

Single piston.—A lever of a setworks that causes knee

movement only on the pull or backward thrust, as

contrasted with the double-acting type, which causes

movement on both forward and backward lever

thrusts.

Skid.—A timber bar or rail used in sets fastened to the

bottom of a machine or structure that is to be slid

on the ground.

Slab.—The exterior portion of a log that is removed to

get a flat face for sawing lumber.

Slasher saw.—A device consisting of several circular

saws mounted on a shaft at intervals varying from

16 to 48 inches and used to cut slabs, edgings, and

other wood refuse into lengths suitable for laths,

firewood, and pulpwood, or for transportation to the

refuse burner.

Softwoods.—The botanical group of trees that have

needle or scale-like leaves and are evergreen for the
118 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

most part—^baldcypress, western larch, and tamarack being exceptions. The term has no reference to

the actual hardness of the wood. Softwoods are often

referred to as conifers, and botanically they are

called gymnosperms.

Solid-tooth saw.—A saw having the teeth cut into its

edge.

Sorted-length piling.—The practice of placing material

of a single length or of a definite series of lengths

in a single pile.

Sound cutting.—A hardwood cutting free from rot,

pitch, shake, and wane but permitted to contain sound

knots and others items listed as defects and excluded

from clear-face cuttings.

Sound defect.—Any defect allowed in sound cuttings,

such as sound knots, sound bird pecks, stain, streaks

or their equivalent, season checks not materially impairing the strength, and worm holes.

Speed reducer.—An apparatus for reducing speed.

Split.—A lengthwise separation of the wood, due to

tearing apart of the wood cells.

Splitter-resaw.—A combination of sawmill equipment

consisting of a circular saw fixed in a trough to rip

into halves logs carried by conveyor chains, and a

horizontal band saw to reduce these halved logs to

merchantable products.

Spreader.—A thin disk or scythe-like blade fixed behind

a circular headsaw to guard against boards and

pieces contacting the rear edge of the saw.

Spring set.—A method of setting saws whereby one

tooth is sprung to the right and the next to the left.

Cross-cut saws are spring-set, as are very narrow

band saws.

Square-faced hammer.—A type of hammer used to flatten the surface and put tension in circular saws.

The face has a rectangular outline with a convex

plane, the curvature conforming to a radius of 9%

inches.

Stickers.—A piece of lumber that separates the different courses of lumber in a pile.

Stock items.—Lumber in even widths from 3 to 12

inches.

Stop shoe.—That part of the setting mechanism on a

sawmill carriage which contacts the peg or backstop

and shuts off further advance of the knees.

Straight friction feed.—Feed-works mechanism entirely

dependent upon friction contacts of moving parts to

give motion to the sawmill carriage.

Subflooring.—Boards placed between the joists and the

finish flooring material.

Surface area.—The area of the sawed surface or, in

wane, corresponding to the sawed surface.

Surfaced stock.—A board, plank, timber, or other

sawed material one or more sides of which are

planed.

Surfaced framing.—Material for joists, rafters, studding, and similar framing items which has been

planed.

Surface measure.—The area of the surface; in lumber

this area is calculated in square feet.

Swage set.—To spread the ends of the teeth of a band

or circular ripsaw. A saw is swage set when the

ends of. the teeth are spread to a width greater than

the thickness of the saw.

Sweep.—A deviation in any direction from a straight

line drawn from one end of a log to the other, excluding the deviation due to taper.

Tail sawyer.—One who stands directly behind the

headsaw in the mill and seizes slabs and boards as

they come from the saw, placing them flat on rolls.

Tally.—A record of the number of pieces and grades

of lumber in a pile.

Tally stick.—See Lumber scale stick.

Tandem rigs in multiple lines.—Several lines of machines, each line having at least two machines, one

placed behind the other.

Taper bar.—A lever attached to the knee of a sawmill

carriage headblock, by means of which any knee may

be placed out of alinement. It is of service when

making the first cuts on swell-butted logs.

Taper block.—See Taper bar.

Tension.—To make a circular or band saw looser in

the center than on the cutting edge.

Tension gage.—Similar to a straight edge but having

a convex edge, the curvature of which exactly coincides with the concave curvature of a properly tensioned saw, used when making the test for tension.

Throat.—See Gullet.

Tie or timber mill.—A sawmill that specializes in ties

or heavy timbers.

Tier.—One of two or more vertical rows, one beside the

other, as of boards in a pile.

Timber.—Sawed material 5 inches or larger in least

dimension.

Top face.—The back of the tooth, that part extending

back from the point along the continuation of the

line forming the gullet of the preceding tooth.

Top roll.—A roll so placed as to press down on the

top of the log, and automatically adjustable to log

irregularities.

Top saw.—The upper of two circular saws on a headsaw, both hung on the same husk.

Tram.—A box-like wagon running on a tramway.

Trial mandrel.—A shaft, collars, nut, bearings, and

frame to support a circular saw when checking its

condition.

Turbine.—A rotary engine actuated by the reaction,

or impulse, or both, of a current of fluid subject to

pressure.

Turning.—Turning the log about on its longitudinal

axis.

Twin circular.—A mill that has both a right-hand and

a left-hand saw; used to slab logs or to rip cants.

Both saws may be so mounted as to permit altering

the distance between them.

Twists.—Ridged projections on the surface of a circular saw.

Unit.—An area, equal to 12 square inches, used in

determining the grade of hardwood lumber.

Universal joint.—Any of various couplings or joints to

permit swiveling or turning at any angle within defined limits.

Upset swage.—A tool used to spread the points of the

teeth of a band or circular ripsaw.

Wane.—Bark or the lack of wood or bark, from any

cause, on the edges or corners of a piece.

Warp.—Any variation from a true or plane surface.

Yarding logs.—The process of moving logs from mill

yard to sawmill.
S,/fH^

INDEX

Page

Accounting 106

Air drying, end coatings for 71

piling for 64

Alleys, lumber-yard 64

Anvils, tension 53

Arbors 8

Babbitt bearings 48

Balance sheets 107-110

Band headsaws, efficient use of 3

sizes of 4

Battery trimmers 29

Bearings 48

Belt conveyors '. 36

Belts, flat 44

capacity of, table for 46

splicing, lacing 44

Belts, transmission capacity of 45

Belts, V-type 45

capacity of, table for 46

Blowers, sawdust 34

Blue stain, dipping tanks for 71

piling to prevent 67, 71

Bolsters, carriage 15

Bookkeeping 106

Boss dogs 24

Box piling 68

Burners 37, 42

Business operations 103

Canadian trim saws 27

Capital requirements 105

Carriages 14

Cars, load-out 83

Chain conveyors . 37

Checking, piling to prevent 66

Chip thickness ' 51

Circular headsaws 3

Commissions, sales 106

Conveyor systems 34

Crews, sawmill 59

Crib piling 70

Crosscut saws, filing 58

Custom mill operation 105

Cut-oiï saws 26, 29

Dead rolls 35

Decay, piling to prevent 71

Derricks, log 61

Detectors, metal 33

Diesel engines 41, 42

Dipping tanks 71

Discounts, sales 106

Dog boards, faulty sizing 100

Dogs 21

Dressing allowances, lumber 98

Dutch-oven furnaces 42

' ''.v. ..; 'i'i\ Page

Edgers, types of ..".."... 25

Edging, hardwood lumber 94

softwood lumber 91

Electric motors 41, 42

End coatings 71

End piling 69

End racking 70

Factory grades, hardwood 95

Feed rate, headsaw 39, 51

Feed works 9

Filing, crosscut saws 58

Filing, sawteeth 56

Financing, mill 105

Flat piling 66

Fork-lift trucks 89

Foundations, lumber-pile 65

Friction-type log turners 32

Furnaces, Dutch-oven 42

Gage, headsaw 50

Gasoline engines 41, 42

Grading, logs 112

lumber 103

Grading rules, organizations issuing 113

Grade standards, softwood 90

Grades, hardwood, analysis of, table for 99

hardwood 95

sawing for 91

softwood logs, table for 113

Guides, headsaw 9

Gullet capacity 40, 50, 51

Gumming sawteeth 57

Hammer bench 53

Hammer dogs 24

Hardwood cutting requirements, table for .... 97

Hardwood logs, milling 91

Hardwood lumber, edging 94

factory grades 94

shrinkage allowance for 94

Hardwood stock, thickness, table for 89

Headsaws, alinement 55

band 3

band, sizes of 4

circular 3, 4

circular, mounts for 5

circular, sizes of 4

circular, size table for 5

classification of 2

diameter 50

faulty alinement 100

feed rates 51

filing 56

gage 50, 53

guides 9

horsepower requirements 39

119
120 HANDBOOK 27, U. S. DEPARTMENT OF AGRICULTURE

^ Page

HeadsaWs, alinement—Continued

horsepower requirements, tables for 40, 41

overloading 39

power consumed by 40, 41

sash-gang 2

speed 51

splitter-resaws 8

tensioning 52

teeth 49

tooth spacing 51

Hoists, log, sling-chain 62, 67

Horsepower ratings 41

Husk rollers 9

Husks, description of 8

Indicators, setworks 21

Inserted sawteeth, styles of 49

sharpening of 56

Insurance, mill Ill

Internal-combustion engines 41, 42

Jackladders, log 62, 66

Jammers, log 61, 66

Jointing, sawteeth 57

Kiln trucks, load-out 86

Knees 15

Labor requirements, general 59

work distribution 60

Leveling, headsaws 52

Licenses 110

Lift trucks, log 61

Live rolls 35

Loading scaffolds 84

Load-out devices 83

Log derricks 61

Log grade specifications, table for 113

Log ponds, lay-out of 61

Log rules Ill

Log skids 61

Log turners 30

Log yards 61

Logs, grading 112

handling 61

hardwood, milling 91

oversized, sawing of 97

sawing 89

scaling Ill

softwood, milling of 89

Lumber, cost of producing 103

grading 102

inaccurately cut 99

marketing 105

rule manufacturers 97

size standards 98

tally footage, table for 101

tally forms 102, 103

tallying 102

thickness variations in 99

yard lay-out 63

Lumber grades, sawing for 89

Lumber piling, box 68

Lumber props 83

\ '. Page

Mandrels, headsaw 7

tensioning 53

Marketing lumber 105

Metal detectors 33

Mill accounting 106

Mill equipment, useful life, table for 110

Milling hardwood logs 91

Mill lay-out 61

log yards 61

plans for 73

Mill management • > 103

operation 89

Mills, insurance for HI

public regulations affecting 110

Mine detectors 33

Mounts, circular headsaw 6

Multiple-saw edgers 25

Offsets 15

Oil motors 10

Overhead log turners . 30

Package piling 68

foundations for 66

Permanent mill, plans for 79

Piling, logs 61

Piles, lumber 64

Piling lumber 64

Plans for mills 73

Ponds, mill 61

Portable mills, plans for 73, 75

Power, belt capacity 45

Power consumption, factors inñuencing 39

Power equipment 39

Power plants, comparison of . 42

Power requirements 39

headsaw 52

tables for 40, 41

Powered rolls 35

Prime movers 41, 42

Production, capital needed 105

Pulleys 47

Racking, end 70

Rails, truck load-out 86

Receders 16

Records, mill operating 106

Refuse burners 37

Regulations, public, affecting mills 110

Rip saws, filing 56

Rip sawteeth 49

Roller, husk 9

Rolls, dead 35

live 35

load-out 83

Roofs, lumber-pile 69

Rules, log Ill

Safety measures Ill

Safety regulations 110

Sales commissions 106

Sales discounts 106

Sap stain, dipping tanks for 71

piling to prevent 67, 71
SMALL SAWMILL OPERATOR'S MANUAL 121

Page

Sash-gang headsaws 2

sizes of 4

Sawdust blowers 34

Sawdust burners 37, 42

Sawdust chains 34

Sawdust, furnaces for 42

Sawing, hardwood logs 92

logs, methods of 90

oversized logs 97

softwood logs 90

Sawmill layout 61

Sawmills, classification of 2

Saws, maintenance of 48

Sawteeth, alinement 55

design 50

filing of 56, 58

gullet capacity 51

gumming 57

inserted, table for 49

maintenance of 48

patterns 58

spacing 51

swaging 56

Scaffolds, loading 84

Seasoning, lumber 63

Semipermanent mills, plans for 73, 77, 79

Set-out blocks 15

Setworks 15

accuracy controls for 20

indicators for 21

Shafting 48

Shapers, sawtooth 56

Sharpening, crosscut saws 58

rip saws 56

Shrinkage allowance for hardwood 94

Shrinkage allowances, lumber 98

Side dresser 55

Side gage 55

Single cut-off trim saws 26

Single-saw edgers 25

Sites for mills 61

Sizes, faulty, causes of 100

Size standards 98

Skids, log 61

Slab cut-off saws 29

Sliding skids, load-out 84

Slip-block log turners 31

Page

Social-security taxes 109, 110

Softwood grade standards 90

Softwood logs, miling 89

Softwood lumber, edging 91

trimming 91

Solid sawteeth 49

Sorted-length piling 67

Sorting lumber, for piles 64

Specialty-mill operation 105

Splitter-resaws 7

Spreader 9

Spring-set sawteeth 49

Stain prevention 67, 71

Steam engines 41, 42

Stickers 68

Swage-set sawteeth 49

Swaging 56

Tally boards 103

footage, table for 101

forms 102

rule manufacturers 97

Tallying lumber 102

Taper bars, on knees 15

Teeth, headsaw 49

Tensioning headsaws 52

Tie mill, plan for 77

Ties, size standards 98

Timbers, size standards 98

Trackways 14

load-out 83

Transmission equipment 39

belts 44

Trash-disposal systems 37

Trimming, hardwood lumber 95

softwood lumber 91

Trim saws 26

Trucks, fork-lift 68, 69

load-out 89

Turners, log 30

Turning sequence, hardwood logs 92

softwood logs 90

Two-saw trim saws 27

V-belts 45

Vertical edgers 25, 26

Wage-hour regulations 109, 110

Warping, piling to prevent 71

Yards, lumber, layout 63

- U. S. GOVERNMENT PRINTING OFFICE: 195B