IMPROVEMENTS IN WOOD SAWING MACHINES, AND IN PART APPLICABLE TO OTHER WOOD CUTTING MACHINES
Year: 1878

page_text: LETTERS PATENT to David Thomson, of the Firm of Thomson and Allan, of
Johnstono, in the County of Renfrew, North Britain, Engineers, for the Inven-
tion of "IMPROVEMENTS IN WOOD SAWING MACHINES, AND IN PART APPLICABLE
TO OTHER WOOD CUTTING MACHINES."
Sealed the 3rd December 1878, and dated the 17th June 1878.
PROVISIONAL SPECIFICATION left by tho said David Thomson at the Office
of the Commissioners of Patents on the 17th June 1878.
DAVID THOMSON, of the Firm of Thomson and Allan, of Johnstone, in the County
of Renfrew, North Britain, Engineers. "IMPROVEMENTS IN WOOD SAWING
MACHINES, AND IN PART APPLICABLE TO OTHER WOOD CUTTING MACHINES."
This Invention has for its object to improve the construction and action of wood
sawing machines, so as to admit of their being driven at a high speed without
inconvenience, and to render them available for various kinds of work.
Some of the improvements relate to the feeding apparatus, and are also advan-
tageously applicable to planing and other wood cutting machines.
In the improved sawing machine the saws are of the vertically reciprocating class,
a number being held in one frame in the usual manner. The saw frame is made to
reciprocate by means of a crank shaft and connecting rod, or in any other suitable
known way, but instead of the frame sliding in guides, it is guided by upper and
lower sets of radius bars forming approximate parallel motions. Each end of the
frame has jointed to it a pair of bars, the outer ends of which are jointed to a cross
head, or to blocks fitted to work in short horizontal guides, whilst at suitable points,
near the middles of these bars, there are jointed short radius bars, which have their
other ends jointed on studs fixed to the framing at points near the central vertical
plane.
An important feature of the arrangement consists in having the short horizontal
guides in blocks which are vertically or otherwise adjustable on the framing, as by
adjusting these guide blocks the motion of the saw frame can be varied as regards

page_text: its precise general direction, and also as regards its direction at various parts of the
stroke, so as to suit different cases, as, for example, cutting in one direction, or
cutting in both directions of its motion, also cutting more or less deeply, according
to the nature of the wood operated on.
The feeding apparatus is by preference arranged to act continuously, provision
being made for passing a single large log through the machine, or two sinaller ones,
and when arranged for two logs, the rollers which bear down on and move the logs
are made separately adjustable to suit different thicknesses of the two logs by being
placed on separate transverse shafts, arranged so that those of one set are sufficiently
in advance of the others for each set of shafts to clear the rollers of the other shafts,
whilst the gearing for driving one set of rollers is arranged on one side of the
machine, and that for the other rollers on the other side.
Another improvement consists in carrying the holding down and feeding rollers
by one or more pistons or rams and cylinders, steam or water or other fluid under
pressure being admitted into the cylinders as required.
This arrangement, whilst securing a uniformity of pressure, notwithstanding
inequalities in the thickness of the log, is more speedy and convenient in use than
the common arrangement of vertical screw shafts geared by bevil wheels to a trans-
verse shaft.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said David Thomson in the Great Seal Patent Office on the 14th
December 1878.
DAVID THOMSON, of the Firm of Thomson and Allan, of Johnstone, in the County
of Renfrew, North Britain, Engineers. "IMPROVEMENTS IN WOOD SAWING
MACHINES, AND IN PART APPLICABLE TO OTHER WOOD CUTTING MACHINES."
My said Invention has for its object to improve the construction and action of
wood sawing machines, so as to admit of their being driven at a high speed without
inconvenience, and to render them available for various kinds of work.
Some of my improvements relate to the feeding apparatus, and are also advan-
tageously applicable to planing and other wood cutting machines.
In my improved machine the saws are of the vertically reciprocating class, a
number being held in one frame in the usual manner. The saw frame is made to
reciprocate by means of a crank shaft and connecting rod, or in any other suitable
known way, but instead of the frame sliding in guides, it is guided by upper and
lower sets of radius bars, forming approximate parallel motions. Each end of the
frame has jointed to it a pair of bars, the outer ends of which are jointed to a cross
head, or to blocks fitted to work in short horizontal guides, whilst at suitable points,
near the middles of these bars, there are jointed short radius bars, which have their
otlier ends jointed on studs fixed to the framing at points near the central vertical
plane..
An important feature of my arrangement consists in having the short horizontal
guides in blocks, which are vertically or otherwise adjustable on the framing, as by

page_text: adjusting those guide blocks the motion of the saw frame can be varied as regards
its preciso general direction, and also as regards its direction at various parts of the
stroke, so as to suit different cases, as, for example, cutting in one direction, or
cutting in both directions of its motion, also cutting more or less deeply, according
to the nature of the wood operated on.
My feeding apparatus is by preforence arranged to act continuously, provision
being made for passing a single large log through the machine or two smaller ones,
and when arranged for two logs, the rollers which bear down on and move the logs
are made soparately adjustable to suit different thicknesses of the two logs.
Another improvement consists in carrying the holding down and feeding rollers
by one or more pistons or rains and cylinders, steam or water or other fluid under
pressure being admitted into the cylinders as required.
This arrangement, whilst securing a uniformity of pressure, notwithstanding
inequalities in the thickness of the log, is more speedy and convenient in use than
the common arrangement of vertical screw shafts geared by bevil wheels to $ trans-
verse shaft.
And in order that my said Invention and the manner of performing the same may
be properly understood, I hereunto append a Sheet of explanatory Drawings, to be
herein-after referred to, and representing my improved arrangements. In these
Drawings the same reference numerals are used to mark the same or like parts
wherever they are repeated. -
Figure 1 on the accompanying Sheet of Drawings is a front sectional elevation
of a saw frame or machine, as fitted with my improved guiding mechanism, and
Figure 2 is a vertical section as at right angles to Figure 1.
The main framing 1 is similar to what is frequently adopted in such machines,
excepting that it is made without the ordinary vertical guides for the saw frame 2,
and is fitted with parts connected with my improved arrangements. The saw
frame 2 is fitted in the ordinary way for receiving the saw blades, which, however,
are not shown in the Drawings, and it is made to reciprocate by a revolving crank
shaft 3, to the crank of which it is connected by the connecting rod 4. To studs
at each end of the saw frame 2 there are jointed two bars 5, which are at their
outer ends jointed upon a transverse horizontal rod 6, having on its ends blocks 7,
fitted to work in short horizontal guide slots 8, in blocks 9, adjustably attached to
brackets 10, formed on or fixed to the main framing. At about the middle of each
bar 5 there is fixed in it a stud to which there is jointed a short radius bar 11, the
inner end of which is jointed on a stud fixed to the main framing.
The combination of bars 5 and 11, and the horizontally guided blocks 7, forms an
approximation to a well-known kind of parallel motion; the guide blocks 9 are
however unlike the corresponding part of the motion as commonly made, adjustable
in position, being fitted in vertical guides in the brackets 10, and being adjustable
therein, for purposes herein-before indicated, by screw spindles 12, fitted with worm
wheels 13. A simultaneous and equal adjustment of the two upper or two lower
guide blocks 9, at both sides of the machine is secured by employing in each case a
transverse horizontal spindle 14, with worms on it gearing with the two worm
wheels 13, and with a hand wheel on it.
The mechanism shown in Figures 1 and 2 for feeding forward the wood log 15,
is of a usual kind with a continuous action. Both stepped pulleys 16, 17, and
reversed cone pulleys 18, 19, are introduced into the driving parts, so that the rate
of feed can be adjusted with the greatest nicety. The details of the feeding
mechanism will be quite well understood from the Figures.
Figure 3 is a plan, and Figure 4 is a sectional side elevation, showing my improved
arrangement of feed rollers adapted for feeding two logs of different sizes through a
sawing machine, or two planks or boards of different sizes through a planing,
moulding, or other machine. The feed rollers 20, for one log or piece 24, are upon
one set of transverse shafts 21, and the feed rollers 22, for the other log or piece 25,
are upon a separate set of transverse shafts 23; and the shafts of the two sets 21,
23, are placed sufficiently far apart horizontally for the shafts 21 to pass at the sides

page_text: of the rollers 22, on the other shafts 23, and vice versa. With this arrangement
both sets of feed roller shafts 21, 23, can pass completely across the machine without
interference, and the driving gear for one set can be at one side of the machine, and
that for the other set at the other side.
A convenient arrangement of parts for applying pressure to the upper rollers is
shown in Figure 10, the bearings of each upper roller 20, 22, being connected by
vertical rods to levers 26, on which suitable weights 27 are adjusted, and of which
the centres are adjustable by means of vertical screws 28. The adjusting screws 28
of each two similar upper rollers are geared by bevil wheels to a horizontal shaft 29,
having cross handles or a hand wheel at the end. The levers 26 of cach pair are
reversed, and the end of one lever rests on the centre of the other when not raised
by the log or wood passing under the rollers.
Figure 5 is a front elevation, and Figure 6 is a sectional side elevation, showing a
modification of my apparatus for applying fluid pressure to the feed rollers 20, of a
sawing or other wood cutting machine. A cylinder 30 is fixed to the framing 1,
above each feed roller 20, and a piston rod 31, passing out through a stuffing box at
the top of the cylinder, has fixed to it a cross head 32, and to this cross head 32
there are fixed two rods 33, which pass down to the roller 20, and hold it by means
of eyes formed on their lower ends, and passed on the shaft of the roller. The
cylinder 30 is formed with passages and ports, and is fitted with a valve which is in
a casing 34, and which is adjustable for admitting steam or other fluid under pros-
sure to the upper side of the piston, for pressing down the roller, or to the under
side of the piston for raising the roller.
Having thus particularly described my said Invention, and the manner of
performing the same, I have to state that I do not restrict myself to the precise
details herein described or delineated; but that what I believe to be novel and
original, and claim as the Invention secured to me by and in terms of the herein-
before in part recited Letters Patent is,―
1. The combination of parts herein-before described for guiding reciprocating saw
frames.
2. The making of the guide blocks (9) adjustable, substantially as herein-before
described.
3. The arranging of the feed rollers of sawing or other wood cutting machines,
substantially as and for the purposes herein-before described with reference to
Figures 3 and 4 of the accompanying Drawings.
4. The pressing of the upper feed rollers of sawing or other wood cutting machines
by means of pistons acted on by steam, or water, or other fluid under pressure, as
berein-before described.
In witness whereof, I, the said David Thomson, have hereunto set my hand
and seal, this Twelfth day of December, in the year of our Lord One thousand
eight hundred and seventy-eight.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
DAVID THOMSON. (L.S.)