Re-Sawing Band Saw Machine

A re-sawing machine is one used to cut lumber (that has already been sawn) into thinner boards. Fig. 3134 represents a band saw machine, constructed by P. Pryibil, having a self-acting feed motion, consisting of four feed rolls, all of which are driven, and two small idle rolls, which are so arranged as to guide the last end of the stuff or work after it has left the driven rolls.

Four rates of feed are provided, and the upper wheel can be set at the required angle from a perpendicular while the machine is in motion.

The upper guide wheel, and the mechanism by which it is carried, is counterbalanced by a weight that hangs within the column or main frame, and is therefore out of sight.

The construction of the parts by means of which the upper wheel is adjusted in height to regulate the tension of the saw, and which also cants the wheel out of the vertical, is shown in Fig. 3135, which represents a portion of the main frame or column, on which is a slideway b, for the slide c, which carries the bearing for the upper wheel.

The method of moving the slide c for moving the upper wheel to adjust the saw tension is as follows:

By means of the handle h and the worm and worm wheel at w, the shaft s is revolved. The upper end of s is threaded into the nut n, which is capable of end motion in its bearing at e, and which abuts against the lever l, the latter abutting against the end of the screw m, and acting at its other end on the rubber cushion p. Now suppose that s be revolved in the direction denoted by the arrow, and the effect will be to raise the nut n. This effect will be transferred through the screw m to the slide c, which will rise up on b, carrying with it the upper wheel bearing and wheel.

When the upper wheel receives the strain of the saw, then the continued revolution of shaft s will cause the nut n to lift endways in its bearing e, the screw m acting as a fulcrum to cause the lever l to compress the rubber cushion p. The amount of tension on the saw is tested by springing it sideways with the hands. Now suppose the saw to be properly strained, and that a piece or chip of wood accidentally gets between the saw and the lower wheel, and the result will be that the slide c will (from the extra strain caused by the chip) move down on its slideway b, which it is capable of doing, because the long arm of the lever l can move down, compressing p, and this will prevent the saw from breaking.

To cant the wheel for leading the saw true to the lower wheel, the following means are provided:

The upper wheel bearing rests on the fulcrum at a, and is guided sideways by the screws c and d. At f is a stud threaded into the bottom half of the upper wheel bearing, the wheels g and h threading upon f. The weight of the upper saw wheel endeavors to lift the end j of the wheel bearing, and wheel h determines how much it shall do so, while wheel g acts as a check nut to lock the adjustment.

The feed rolls are carried in slides which are operated in slideways by means of screws, and the two back rolls, or those nearest to the column are maintained vertical. The two front ones, however, are provided with means by which they may adjust themselves to bear along the full depth of the work, notwithstanding that it may be taper. The construction by means of which this is accomplished is shown in Figs. 3136 and 3137, in which a is front and b a back feed roll. The bearings of feed roll a abut against rubber cushions c, c, whose amount of compression is regulated by the set screws d, d.

The construction of the saw guides is shown in Fig. 3138, which is a plan view partly in section. s s are hardened steel plates set up to the saw by means of studs whose nuts are shown at n n. w is a friction wheel which supports the saw against the thrust caused by the work feeding to the saw. The adjustment of the wheel w to the saw is obtained by means of the wheel h.

The hand wheel h operates the screw r r, that adjusts the wheel w to the saw, the wheel j serving to lock the screw in its adjusted position.

VOL. II. BAND SAW WITH ADJUSTABLE FRAME. PLATE XXII.

Fig. 3139 represents Worssam’s band saw machine, in which the standard may be set at any required angle for cutting bevels.

When the work is heavy and not easily handled it is preferable to set the standard and saw at the required angle, rather than to set the table at an angle and have the saw remain vertical. In Worssam’s machine this is accomplished as follows:

a is the main frame carrying the work table t, and having circular guideways b, b′, which carry the standard c having guide c′ for working in the circular guideways b, b′.

The saw-driving wheel d, is carried in bearings provided in c, and, therefore moves when the standard c is moved.

At the upper end of c, is the slide e, which carries the bearing for the upper wheel f, this slide being adjusted to regulate the saw tension by the hand wheel o, whose screw threads into a nut in the slide e. h carries the front guide g, for the saw, the back guide g′ being carried by a bracket bolted to c. The back guide is fixed in position, but the front one is adjustable to suit the height of the work by raising or lowering it.

The means for setting the saw at the required angle to the work table are as follows:

At the back of the standard c is a rack j, whose pitch line is an arc of a circle of which the axis of the guideway c′ is the centre.

Into the rack j fits the worm wheel k, at the bottom of the shaft of which is a pair of bevel gear wheels l, which are operated by the hand wheel m.

VOL. II. BAND SAW MILL. PLATE XXIII.

A band saw machine constructed by Messrs. London, Berry & Orton, is shown by Figs. 3140, 3141 and 3142, in plate XXIII. The saw-driving wheel d, has wrought iron arms turned true and screwed into the wheel hub. The wooden segments have their grain lengthways of the rim, and between them are placed pieces of soft wood with the grain across the rim. This acts to keep the joints tight, notwithstanding the expansion and contraction of the wood.

The upper wheel is adjusted for straining the saw, and for leading the saw true, by the following construction. It is carried in a U-shaped frame f, which is pivoted at y to a slide that is gibbed to the main frame, and by operating the screw shown at x, the frame f is set to the required level.

To regulate the tension of the saw, the hand wheel k is operated, which drives the pair of bevel gears j and i, the latter of which operates the threaded shaft h, whose upper end g connects with the slide which carries f. Within g is a spring to act as a cushion to the slide, and thus prevent saw breakage should a chip pass between the saw and its driving wheel.

The saw guide frame is secured to the main frame at m′, m′. Upon the face of m, is a slideway for the saw guide arm n, which may thus be adjusted as closely to the upper face of the work as possible.

The weight of arm n is counterbalanced by a rope passing over the pulley v, and supporting the counterbalance weight w. The feed motion is constructed as follows:

On the same shaft as the main fast and loose pulleys a, b, is the feed pulley l, which by belt connection drives pulley m, which is on the shaft w, upon which is a friction disc n, by means of which the rate of feed is regulated. The feed disc n drives the wheel o; the degree of contact between these two (n and o) is regulated by means of the weight t, on the lever u.

On the same shaft as the friction wheel o, is a pinion driving the gear x, which is on the same shaft as the pinion y, which drives the two gears y′ and y′′.

Referring now to Fig. 3142, gear y′ drives the pair of bevel gears z and z′, for the feed roll e, and the pair of bevel gears shown at z′′, the feed roll f. The gear y′′ drives similar gearing for the feed rolls e′ and f′, seen in the plan Fig. 3140.

Referring now to the plan Fig. 3140, and the side elevation, Fig. 3142, the feed roll f is carried in a frame g, which is fitted on the slideway d, d, and receives a screw i, upon which is a hand wheel h; at the back of this wheel is the lever j, which is weighted as shown, so that the force with which feed roll f grips the work is determined by the weighted lever j, and may be varied to suit the nature of the work by moving the weight along j.

The construction of the gear for feed roll f′ is similar, as may be seen in the plan Fig. 3140, f′ being in a slide g′, which has a screw i′, and hand wheel h′, a weighted lever corresponding to j acting against wheel h′. In proportion as f and f′ are opened out to admit thick stuff or work, the hand wheels h and h′, respectively are used to screw the screws i and i′ into their respective slides g and g′, and thus maintain the weighted levers in their requisite horizontal positions. The feed rolls e and e′ are carried in slides c and c′, and are adjusted to suit the thickness of the stuff or work by a hand gearing, which consists of the hand wheel a, seen in the plan and in the front elevation, Fig. 3141, which drives the pinions b and b′, which operate screws for the slides c and c′, the latter being a left hand screw. The front rolls e and e′ are therefore held in a fixed position, whereas the back ones f and f′ may open out under the pressure of the weighted levers j, and thus accommodate any variation in the thickness of the work.

The rate of feed is varied to suit the nature of the work by the following construction: The friction wheel o and the hand wheel r are connected by a yoke q, Fig. 3142, at the ends of which are the joints p, q, seen in the plan, Fig. 3140. Hand wheel r is threaded to receive the screw s, and it follows that by revolving r, the friction wheel o may be moved towards the centre of the friction disc n, which would reduce the velocity with which n would drive o, and therefore reduce the rate of feed. If the friction wheel o be moved from the position it occupies in the plan Fig. 3140, to any point on the other side of the centre of the friction disc n, the direction of feed motion would be reversed.

A band saw machine for the conversion of logs into timber, and constructed by Messrs. London, Berry & Orton, is shown in Fig. 3143. The logs are fixed to the carriage by dogs and the carriage traverses the log to the feed.

VOL. II. LOG CROSS‑CUTTING MACHINE. PLATE XXIV.

Reciprocating Cross Cutting Saw For Logs.—The machine shown in Figs. 3144 and 3145 is designed for the purpose of cutting heavy and long logs into convenient lengths preparatory to cutting the logs up in other machines, and it is usually therefore placed at the entrance to the mill, where it is of immediate service as the lumber comes into the building.

The machine here shown is intended for logs up to 36 inches in diameter, is simple in construction, requires very little foundation, is easy to handle, and occupies but very little room.

The saw is here fed mechanically to its cut, whereas in some machines it is fed by its own weight, and therefore requires great care to be taken, when the saw is finishing its cut, in order to prevent it from falling after it has passed through the log.

Fig. 3145 is a side elevation and Fig. 3144 a plan of the machine, in which a is the frame of the machine on which are the bearings for the shaft b carrying the fast pulley c, loose pulley d and fly-wheel e at one end, and at the other, a crank disc f, whose pin is shown at g. This drives the saw k through the medium of the connecting rod h.

The saw is fast at the butt end to along slide j, j, which works in a long guide formed on the face of the swinging frame l, which pivots at one end on the shaft b and at the other is carried by a slide p, on the vertical slideway m, and is fed down the same to give the saw its cut by the screw whose hand wheel is shown at n.

v is a second guide for the saw, and being connected to the slide feeds down with the saw until it meets the log.

A counterweight w balances the weight of the slides and saw, so that there being a pit beneath the balance weight the saw and its guides may be raised so that the saw stands out of the way when not in use. y is a dog for holding the log, which is also blocked by the wedges z z′.

The construction of the main bearing is shown in Fig. 3146, in which it is seen that the hub or boss of the loose pulley is much longer than that of the fast one, thus providing a large amount of bearing surface, which is advantageous because the belt will remain longer at the loose pulley than it will on the tight one. The sleeves or bushes in which the shaft runs afford a simple means of renewal to restore the fit when the shaft has worn loose in its bearings.

It is obvious that as the guide frame l is pivoted to the shaft b, it carries the end of the saw (as it is fed down) in an arc of a circle of which the axis of b is the centre, whereas the slideway m is straight, and slide p therefore moves in a straight line instead of in the required arc. Provision however is made to accommodate these two motions as follows:

Fig. 3147 is a sectional view of the slides on the slideway m and Fig. 3148 a plan of the same. The hand wheel n corresponds to n in Fig. 3145. Upon the vertical slideway (in Fig. 3145) of the standard fits the slide p, which has a horizontal slideway for the slide r, which is free to slide automatically, having no screw or other device to restrain it, save the guide frame l, and therefore as this frame is lowered to feed the saw the slide r moves automatically to accommodate the arc of a circle in which the guide moves on account of being pivoted at b.

Horizontal Saw Frame.—This machine is designed for the more expensive woods, such as mahogany, and is finding much favor because it will cut at a very high speed, the saw travelling about 150 feet per minute.

The roughest shaped trunk may be easily fixed on the travelling table, and a thin saw may be used as it may be very tightly strained. This machine is used either for breaking down timber, or for converting it from the log to any desired thickness, the thickness of the boards being very readily and easily varied.

The machine consists essentially of a framework carrying either one or two very thin and tightly strained saws operating horizontally and cutting on both strokes, so that the feed is continuous, the construction being as follows:

VOL. II. HORIZONTAL SAW FRAME. PLATE XXV.

Referring to Figs. 3149 and 3150, a is a base plate or bed carrying two uprights or standards b, b, having guideways c, c, for the cross-head d, which has slideways e, e′, for carrying the frame f, f, which carries the saw g, which is guided on each side of the work by the guides h, h′.

The frame f, f is connected to the slides j, j′, and has the rod k, to which the connecting rod pin l is attached, and the rod m, which acts as a stretcher. A connecting rod p, connects the pin l to the crank pin q, on the crank q′, which is driven by belt from the pulley t, a fly-wheel being provided at s.

It is obvious that as the crank revolves the saw reciprocates, its line of motion being determined by the guideways e, e′.

The construction of the saw is shown in Fig. 3151, and it is seen that for half its length, the teeth are formed to cut when the saw moves in one direction, while for the other half the teeth slope in the opposite direction, and are therefore arranged to cut when the saw is on the opposite or return stroke, and the construction whereby the saw is enabled to cut on both strokes is obtained as follows:

Referring to Fig. 3149, the two slides e, e′, on which the saw-carrying frame f f slides, are not in line or parallel one with the other, but each slide is at an angle of about 85 degrees to the line of feed, so that as frame f is reciprocated at each stroke, one end of the saw advances towards the cut, and the other recedes from it, thus causing the saw to cut first on one half and then on the other of its length, one half cutting on the forward, and the other on the return stroke.

The studs or saw-buckles for attaching the saw to the frame are shown in Fig. 3151, in place on the ends of the saw, the part i, that fits in the frame f, Fig. 3149, being squared so that the saw cannot be twisted in tightening up the nuts of the saw-buckle.

The belt works for driving the saw are arranged as follows: at t are the fast and loose pulleys for driving pulley r, the belt passing from t over two pulleys (shown dotted in, Fig. 3149), u, u′, whence it stretches to the crank driving pulley r, whose bearing is provided on the cross-head, so that the two move together when the cross-head is altered in height from the work-table or carriage, to accommodate different thicknesses or diameters of logs.

It is obvious that in proportion as the cross-head is set nearer to the carriage, the belt from t to u, u′ would become slack; provision is made however, to prevent this as follows:

Pulley u, is carried on a frame or swing lever x, to which is attached by rope v the weight w, which therefore regulates the tension of the belt.

The cross-head d may be raised or lowered by belt power or by hand, as occasion may require, the usual course being to move it to nearly the required position by belt power, and then complete the adjustment by hand, a graduated scale being provided as shown, whereby the rack can be set to cut the required thickness of plank without measuring the timber.

The belt motion for raising or lowering the cross-head is obtained by the pulleys at y, the wheel for the hand adjustment being shown at y′. In either case the bevel gear wheels z, z′ operate, respectively, a vertical screw engaging a nut on the cross-head.

The log feed is obtained by a motion separate from the return motion, there being three rates of feed and a quick return motion, the construction being as follows:

Referring to Figs. 3149 and 3150, a is a belt pulley fast on the crank shaft, and driving pulley b, which is also shown dotted in. Pulley b drives the vertical shaft c, on which is the cone pulley d, having three steps, and which drives (by means of belt d′) cone pulley e, on which is a worm f, driving the worm wheel g, which runs idle on its shaft unless engaged therewith by means of the clutch h. The shaft of worm wheel g is omitted in Fig. 3149, so as to leave the belt-shifting mechanism for pulleys q, q′ exposed to view. On this shaft however is a pinion driving the gear wheel k, on whose shaft is a pinion l, driving the gear m, which engages the rack n, on the under side of the carriage.

The clutch h is engaged by the lever i, to the upper arm of which is attached the rod j, j, from the lever p, hence operating p (which is done by hand), back and forth, throws clutch h into and out of gear with the worm wheel g, and puts the carriage feed on or throws it out, according to the direction in which p is moved.

The upper end of shaft c is carried in a bearing on the cross-head, and is provided with a featherway or spline, so that as the cross-head is raised or lowered the upper end of c passes through its upper bearing, and the pulley b travels with the cross-head. The three rates of carriage feed are obviously obtained by means of the three steps on the cone pulleys d and e.

We have now to explain the construction of the mechanism for traversing the table back, and giving it a quick return motion, or in other words a quicker motion on the back than on the feed traverse, and this is arranged as follows:

q, is a fast and q′, q′′, are loose pulleys, one driven by an open belt r, Fig. 3150, and the other by a crossed belt r′, from a countershaft. The belt-shifting forks are operated by lever s, whose upper end engages with the rod t, which is operated by the lever u.

The loose pulleys q′ and q′′ are twice as wide as the fast pulley q.

Now suppose that lever u is moved to the right, and the belt would be moved from the loose pulley q′′ to the fast pulley q, while the other belt would merely be moved or shifted from one to the other side of loose pulley q′.

Similarly if lever u, be moved to the left, the belt on the loose pulley q′ will be moved on to the fast pulley q, and the belt on pulley q′′ would simply be moved across the face of the pulley, and as the countershaft pulleys for the two pulleys are of different diameters, therefore two rates of motion are obtained.

The shaft v, on which pulley q is fast, drives the pinion l, which drives m, the latter gearing with the rack beneath the carriage.

The carriage is guided by the wheels z, which are secured to it, and run on the iron guideways z′, the flanges of the wheels preventing side play, and causing the carriage traverse to be in a straight line.