United States 

Department of 

Agriculture

Forest Service 

Forest

Products

Laboratory

Research

Paper

FPL 438 

Maximum Cutting 

Yields for 6/4 

Ponderosa Pine 

Vertical Grain 

Lumber

Kent A. McDonald

Pamela J. Giese

and

Richard O. Woodfin
Abstract Acknowledgment

The moulding and millwork industries process nearly 1.3 

billion board feet of Ponderosa Pine annually. Unfortunately, 

thousands of trees are harvested unnecessarily to 

compensate for less than optimum processing. To help 

improve this situation, researchers at the Forest Products 

Laboratory developed maximum cutting yields for 6/4 

Vertical Grain Ponderosa Pine lumber in grades No. 1, No. 

2, and No. 3. Yields were developed by building a

representative 6/4 Vertical Grain lumber data base and 

simulating sawing of the lumber by the computer program 

OPTYLD. Results may be used to compare cutting yields 

between 6/4 Vertical Grain grades, to guide grade selection, 

and to estimate possible improvements in processing. 

Results also encourage more automation in lumber 

processing.

This paper is part of a series by the U.S. Department of 

Agriculture, Forest Service, Forest Products Laboratory on 

maximizing cutting yields of 5/4 and 6/4 Shop, and 6/4 

Vertical Grain lumber. 

The Timber Quality Research Project of the USDA Forest 

Service Pacific Northwest Forest and Range Experiment 

Station, Portland, Oreg., made a significant contribution to 

the completion of this study through their assistance and 

expertise.
United States 

Department of 

Agriculture

Forest Service 

Forest

Products

Laboratory1

Research

Paper

FPL 438 

September 1983 

Introduction

Maximum Cutting 

Yields for 6/4 

Ponderosa Pine 

Vertical Grain 

Lumber

Kent A. McDonald, Research Forest Products Technologist

Pamela J. Giese, Computer Programmer

and

Richard O. Woodfin, Forest Products Technologist

Pacific Northwest Forest and Range Experiment Station

Portland, Oregon 

The moulding and millwork industries consume about 1.3 

billion board feet of Ponderosa Pine lumber annually. A

sizable portion of the volume consumed is in 6/4 Vertical 

Grain lumber. Because of manual processing operations 

and high production speeds, many processing inefficiencies 

occur. The purpose of this research is to develop maximum 

cutting yield information for individual grades that can help 

improve the efficiency of such operations. 

The industry resaws cants to produce Vertical Grain lumber 

for the millwork market. These cants are sawn into boards 

with widths equal in size to the cant thickness. Boards 

produced in this manner feature edge grain or vertical grain 

characteristics, hence the nomenclature Vertical Grain. 

Vertical Grain, sometimes referred to as “Sized Shop”, is 

graded under the Jamb and Headstock rules of the Western 

Wood Products Association (WWPA) (2)2

 (par. 97.00). 

Information on the clear cutting yields of 6/4 Vertical Grain 

lumber has been unavailable and awaiting the sophistication 

of the computer. With this tool now available, we developed 

the information by obtaining a board data base for 

computer simulation of the cut-up operations for Vertical 

Grain lumber; developing maximum clear cutting yields for 

No. 1, No. 2, and No. 3 grades of Ponderosa Pine Vertical 

Grain lumber; and developing yield data on cuttings 

salvageable from defective pieces (“ripped” clear cuttings). 

This report is the third in a series (6,7) aimed at improving 

the efficiency of utilization of Shop and Vertical Grain 

lumber in the moulding and millwork industry. 

1

 Maintained at Madison, Wis., in cooperation with the University of 

Wisconsin.

Study Procedures 

Sampling

A 5,374-board-foot sample of 6/4 Vertical Grain lumber was 

selected (7) from mills located throughout the geographical 

range of ponderosa pine (fig. 1). This lumber was selected 

to locate and measure the size and distribution of defects. 

All sample material was inspected by Quality Supervisors of 

the WWPA to verify the grade and scale. If a supervisor 

determined any board was misgraded it was changed to the 

correct grade. Each board was numbered and its grade and 

measurements recorded. Board measure for these 6/4 

boards was obtained by the standard procedure of 

multiplying surface measure by 1.5. 

All samples were 4-7/8 inches wide and ranged in length 

from 10 to 16 feet. Only eight boards sampled from the No. 

3 and Better mix graded No. 1 (table 1) and are not 

considered representative of the grade. 

Data Collection 

A complete digital record was made of each board and all 

defects, including the type of defect and its location, to the 

nearest 1/4 inch. Board data recorded include board 

number, grade, unit number, width, length, gross surface 

measure. and net surface measure. 

Defects were measured on both sides of each board (fig. 2) 

using a measuring table designed for this purpose. Defects 

were tallied by type and four coordinate points of a

quadrilateral which contained the defect (fig. 3). All wood 

was classified as either defect or clear. Any blemish not 

acceptable in a clear cutting was classified as defect and 

recorded.

2

 Italicized numbers in parentheses refer to literature cited at end of this 

report.
Figure 1 .—Distribution of ponderosa pine. (ML83 5059) 

Figure 2.—Board measuring procedure. (M 148959) 

Table 1.—Sample data, 6/4 Ponderosa Pine Vertical Grain 

Grade

Number

of

boards

Total Average

volume volume per board 

– – – – – –Board feet1 – – – – – – 

No. 1 8 84 10.5

No. 2 317 3,264 10.3

No. 3 197 2,026 8.6

Combined 522 5,374 10.3

1

 Scaled net surface measure times 1.50. 

Simulated Board Processing Program 

(OPTYLD)

The maximum clear cutting yields for the 6/4 Vertical Grain 

lumber were determined using a specially designed 

computer program, OPTYLD (pronounced opt yield) (5). 

Although specifically developed for obtaining the maximum 

clear cutting yield from random-width lumber, the OPTYLD 

program was easily adapted to calculate the yield of fixedwidth boards. Crosscut first, followed by ripping, are the 

operations typically used to produce cuttings from the 

Vertical Grain lumber. The single width of Vertical Grain 

lumber eliminates the need for the initial ripping operation 

common to processing of random-width 5/4 and 6/4 Shop 

grade lumber. 

The computer program OPTYLD combines the digital board 

and defect data of both faces and selects the sawing 

solution that results in the highest value and/or yield of 

clear cuttings. To obtain the best crosscutting solution, all 

full-width clear cuttings longer than 9 inches are determined 

and their values computed. After the best crosscutting 

solution is selected, the remaining defective pieces are 

assessed for additional clear cuttings obtained by ripping. 

For the Vertical Grain lumber, crosscutting was specified to 

produce fullwidth, random-length clear cuttings, 9 inches 

and longer in increments of 1 inch but not to exceed 84 

inches. The remaining defective pieces were ripped to 1.75, 

2.5, 3.0, and 3.5 inches. The limits (constraints) of this 

computer model are: 

–maximum board length of 16 feet 

–only clear, two-face cuttings can be obtained 

–1/4-inch increments used to describe the clear cutting 

dimensions, defect coordinates, board size, and saw 

kerf.

2
Methods and Results 

Figure 3.—Defect measuring procedure. (M148955, M148954) 

Table 2.—Relative cutting value index, 6/4 Ponderosa Pine 

Vertical Grain 

Width Cutting length (inches) 

9-12 13-19 20-26 27-35 36-47 48-59 60-71 72-83 84

In. – – – – – – – – – – –Value1

 per 1,000 ft2– – – – – – – – – – – 

2.50 800 810 820 840 860 880 1,000 1,030 1,150

3.00 800 810 820 840 860 880 1,000 1,030 1,150

3.50 810 830 840 860 880 910 1,040 1,070 1,200

4.50 820 840 850 870 890 930 1,080 1,120 1,250

4.75 825 845 855 875 895 950 1,100 1,145 1,300

1

 Value has no units. 

The maximum clear cutting yields were computed for the 

Vertical Grain sample by computer simulation using 

conventional processing procedures. These maximum yields 

were compiled by lumber grade from the individual board 

solutions. Boards were crosscut into the longest length, fullwidth clear cuttings obtainable from 9 to 84 inches long. A

cutting value index (table 2) was developed to compare the 

value of different size cuttings so that the highest return 

from each board could be calculated. The values are based 

on information from industry cooperators and are assumed 

to represent industry practice. Note that these units are not 

dollars.

A summary of the full-width clear cuttings calculated per 

1,000 board feet (table 3) shows the distribution by grade 

and by cutting length groupings. Longer cuttings come from 

grade No. 1 and proportionately shorter cuttings from No. 

3. The total lengths of all cuttings per 1,000 board feet are 

summarized in table 3. They are respectively 1,294, 1,139, 

and 808 lineal feet for grades No. 1, No. 2, and No. 3. 

Yields of ripped clear cuttings were computed for the No. 2

and No. 3 grades of Vertical Grain (table 4). The No. 1 did 

not produce any ripping yield, apparently due to its high 

quality or the small (eight) sample of boards. The 

distribution of ripped cuttings by width and length shows 

the increase in yield from the ripping operation. The 

summary of yield for crosscut and ripped clear cuttings by 

area and value (table 5) shows a 7.1 percent increase in 

total cutting area for No. 2 and an 18.6 percent increase for 

No. 3. Likewise, value increases from the ripping operation 

are 6.6 percent for No. 2 and 18.1 percent for No. 3. 

The relative difference that occurs between the grades of 

Vertical Grain lumber is evident from the values obtained 

per unit area of cuttings, the recovery percentages, and the 

calculated values of clear cuttings per board measure as 

shown in table 6. (Remember, these values have no units 

and are derived using values from the cutting value index in 

table 3). 

The value per unit of clear cuttings obtained for each grade 

is calculated by: 

(1)

where V = total value of clear cuttings 

A = total board area in clear cuttings (ft2

)

UV = value per unit of clear cutting 

These values are 1.073, 0.907, and 0.863 for grades No. 1, 

No. 2, and No. 3, respectively. 

3
Recovery of clear cutting area relative to the board footage 

in the sample is obtained by: 

Finally, the cutting value obtained for 1,000 board feet is 

calculated by: 

(2) (3)

where A = total board area in clear cuttings (ft2) where V = total value of clear cuttings 

B = total board feet in sample 

V/M = value per 1,000 board feet 

By grades, the cutting values per 1,000 board feet are 524, 

417, and 321 for No. 1, No. 2, and No. 3, respectively. 

Assuming the relative value index used was realistic, these 

cutting values should represent the absolute differences 

between these grades. 

B = total board feet in sample

R = percent recovery of cutting area to board

feet

By grade, recovery percents are 48.8, 46.0, and 37.2 for 

No. 1, No. 2, and No. 3, respectively. To convert these 

values to percent recovery of cuttings in board feet, multiply 

the percentages by 1.5. 

Table 3.—Crosscutting yield1 to board measure, 6/4 Ponderosa Pine Vertical Grain 

Grade Cutting length class (inches) Lineal feet cuttings 

9-12 13-19 20-26 27-35 36-47 48-59 60-71 72-83 84 per 1,000 board feet

– – – – – – – – – – – – – – – – – –Full-width cuttings per 1,000 board feet – – – – – – – – – – – – – – – – – – 

No. 1 59.5 178.6 47.6 23.8 23.8 23.8 0 11.9 83.3 1,294

No. 2 95.9 123.2 90.4 88.5 52.7 36.8 16.2 6.1 3.1 1,139

No. 3 139.6 180.1 93.3 56.3 24.2 5.4 1.5 .5 2.0 808

Does not include ripped cuttings. 

Table 4.—Ripped yield to board measure, 6/4 Ponderosa Pine 

Vertical Grain 

Cutting length class (inches) Width 9-12 13-19 20-26 27-35 36-47 48-59 60-71 72-83 84

In. – – – – – –Ripped pieces per 1,000 board feet – – – – – – 

GRADE NO. 1

(No ripped yield) 

GRADE NO. 2 

1.75 15.3 8.3 4.6 1.2 0.3 0.3 0.3 0.3 0.3

2.50 11.3 4.6 2.1 .6 .3 ——— —

3.00 9.8 5.5 .6 . 3 .3 ————

3.50 21.4 11.9 4.9 2.1 1.2 .6 — — . 3

GRADE NO. 3 

1.75 20.2 13.8 5.9 6.9 5.4 2.5 .5 1.0 —

2.50 15.3 16.8 6.4 3.9 — .5 .5 — —

3.00 12.3 11.3 4.4 1.0 1.0 2.5 — — —

3.50 37.5 26.2 5.9 3.0 2.0 1.0 — — —

Table 5.—Crosscut and ripped cutting yield summary, 6/4 

Ponderosa Pine Vertical Grain 

Shop Total cutting area Total value 

grade Crosscut Ripped Ripped Crosscut Ripped Ripped 

Ft2 Ft2 Pct (

1

) (1) Pct

No. 1 41 0 — 44 0 —

No. 2 1,394 106 7.1 1,270 90 6.6

No. 3 614 140 18.6 532 118 18.1

1

 Value has no units. 

Table 6.—Total recovery from 6/4 Ponderosa Pine Vertical 

Grain

R = 2

V/M =

B 1

V A 100A/B 1,000V/B 

Total Total Total

UV = V/A Recovery Cutting Value Grade board value of area of per unit cutting value

measure cuttings cuttings cutting area to per 1,000 

board board

measure feet

Board Ft2 V/ft2 Pct

feet

No. 1 84 44 41 1.073 48.8 524

No. 2 3,264 1,360 1,500 .907 46.0 417

No. 3 2,026 651 754 .863 37.2 321

1

 Value has no units. 

2

 Value has no units. M = 1,000 board feet. 

4

1
Summary Literature Cited 

Completion of the 6/4 Vertical Grain cutting yield study 

provides maximum clear cutting yield information for three 

grades. Although the board sample is small for grade No. 1, 

the samples for grades No. 2 and No. 3 are considered a

valid data base. Using the OPTYLD computer program, the 

maximum cutting yields were determined with consistency 

and without human bias. The results present valuable 

information about yield differences between grades of 

Vertical Grain lumber. This should permit mill operators to 

schedule and allocate individual grades for processing as an 

alternative to the present practice of combining all grades. 

These cutting yields also make it possible for mill operators 

to investigate potential processing improvements and 

calculate production requirements against lumber grade 

input. Mill personnel can now collect their own board data 

for computation of maximum yields using the OPTYLD 

computer program. The program options can then be 

tailored to any desired mill conditions for improved 

processing.

1. Wood Moulding and Millwork Producers. From tree to 

trim. Portland, OR: Wood Moulding and Millwork 

Producers; 1975. 96 p. 

2. Western Wood Products Association. Standard

grading rules for western lumber. Portland, OR: 

WWPA; 1978. 

3. Benson, Robert E. Wood for millwork. USDA Forest 

Serv. Res. Pap. INT 89. Ogden, UT: Intermountain 

Forest and Range Experiment Station; 1971. 10 p. 

4. Erickson, Bernard J.; Markstrom, Donald C. Predicting 

softwood cutting yield by computer. USDA Forest Serv. 

Res. Pap. RM 98. Fort Collins, CO: Rocky Mountain 

Forest and Range Experiment Station; 1972. 15 p. 

5. Giese, Pamela J.; McDonald, Kent A. OPTYLD—A

multiple rip-first computer program to maximize cutting 

yields. USDA Forest Serv. Res. Pap. FPL 412. 

Madison, WI: Forest Products Laboratory; 1982. 33 p. 

6. McDonald, Kent A.; Giese, Pamela J.; Woodfin, 

Richard O. 5/4 Ponderosa Pine Shop grade cutting 

yields. USDA Forest Serv. Res. Pap. FPL 394. 

Madison, WI: Forest Products Laboratory; 1981. 12 p. 

7. McDonald, Kent A.; Giese, Pamela J.; Woodfin, 

Richard O. Maximum cutting yields for 6/4 ponderosa 

pine shop lumber. USDA Forest Serv. Res. Pap. 

FPL 437. Madison, WI: Forest Products Laboratory; 

1983. 8 p.

8. Petro, F. J.; Lamb, F. M. Yield of clear cutting from 

lower grades of eastern white pine. Can. Dep. of For. 

and Rural Dev. Publ. No. 1227. Ottawa, Ont., Can.; 

1968. 14 p. 

9. Stern, A. R.; McDonald, K. A. Computer optimization 

of cutting yield from multiple-ripped boards. USDA 

Forest Serv. Res. Pap. FPL-318. Madison, WI: Forest 

Products Laboratory; 1978. 12 p. 

10. Wise, Harold F. Lumber recovery from old growth 

ponderosa pine and sugar pine on the Stanislaus 

National Forest-California. California Regulations. San 

Francisco: U.S. Department of Agriculture, Forest 

Service; 1964. 26 p. 

U.S. GOVERNMENT PRINTING OFFICE: 1983 654 025 4020 5
McDonald, Kent A.; Giese, Pamela J.; Woodfin, Richard O. 

Maximum cutting yields for 6/4 Ponderosa Pine Vertical Grain lumber. USDA 

Forest Serv. Res. Pap. FPL 438. Madison, WI: Forest Products Laboratory; 

1983. 5 p. 

Less than optimum utilization of Ponderosa Pine 6/4 Vertical Grain lumber causes 

unnecessary losses to the timber resource. From a representative lumber data 

base and simulation of the lumber sawing process, the maximum clear cutting 

yield for 6/4 Vertical Grain lumber was determined using the computer program 

OPTYLD. Processors of Vertical Grain lumber can compare their yields with the 

computer yields by lumber grade, can improve grade selection, and can estimate 

improvements in processing. 

Keywords: Maximum cutting yields, crosscutting, Vertical Grain grades, 

moulding and millwork, sawing simulation, computer processing, 

utilization research.