CHAPTER IV.

CIRCULAR SAW BENCHES-continued.

THERE are a considerable number of circular saw benches made with self-acting feed motions, to bring the timber up to the saw when too heavy or laborious to be pushed through by hand. These feeds vary according to the class of work to be performed. Mr. Samuel Worssam in 1873 received provisional protection for a simple feed especially adapted for deals and battens; before this date, however, the writer had applied the same plan to benches driven by hand. It consists of a grooved or serrated roller, or rollers, mounted in bearings underneath the table, whose periphery works partly in an opening in the table, and extends a slight distance above its surface, to ensure the wood to be cut resting thereon. Rotary motion is communicated to the roller by suitable gearing, capable of adjustment to enable the speed of the feed roller to be regulated as desired. Holding-down rollers, or means as heretofore used, are dispensed with, and the pressure of the saw when cutting is relied on solely to keep the wood in contact with the feed roller. Included in this specification is an improved method of 'packing' the saw. For this purpose loose blocks are employed on each side of the saw, each block being fitted with adjustable

packing pieces. The loose blocks are fitted in guides, fixed to the under side of the table and to the 'fillingin piece,' and two screws are fitted to each block, to work in nuts carried by the table and the filling-in piece, so that the ends of the screws extend to the outer edges of the table. Thus by turning the screws the loose blocks, with the packing pieces therein, can be adjusted for different thicknesses of saws.

No very striking novelty in connection with circular saw benches was shown in the recent International Exhibition in Paris. Messrs. Bollinder, of Stockholm, exhibited a saw bench for edging purposes. It was fitted with a horizontal plain roller-feed. Part of the top of the bench and one saw were adjustable by means of a hand lever to the widths of the wood. A neat pendulum or vibrating cross-cut saw, especially designed for sawing barrel staves, was shown by F. Arbey, Paris. The stave to be sawn is bent under a powerful spring, placed on a swivelling frame, which can be set to any angle. The pendulum with saw is brought over by hand, and one side of the stave is sawn; the swivelling frame is then set over the width of the stave, and the saw performs the same operation on the other side.

A small machine for sawing out wooden cogs was shown in the Swiss section. The wood is fixed in a vice fitted on a circular revolving table, and is operated on by two circular fine-toothed saws, running vertically and horizontally; when the tooth is cut on one side, the circular table is made to revolve, and the other side of the wood is served in the same manner.

Important though the subject is, our space will not permit us to notice all the varied forms and modifica

tions of circular saw benches and their adaptation to different classes of work; we shall, however, briefly nótice some few of the most important. For crosscutting heavy logs, where any considerable quantity are done, the best plan is to arrange at the end of the saw mill where timber enters, below the floor, a large circular saw, which can be raised and depressed by suitable gearing above and below the floor line, and cut through the log as it lies on the ground; this effects a considerable economy in labour, especially when the timber has to be converted by other machines and the full length of the log is not required. For light crosscutting purposes, a pendulum bench is a very useful form; in this case the saw is fixed to a frame or pendulum, which swings on a countershaft below the floor line. The saw is made to oscillate by self-acting gear, or can be brought to the wood by means of a treadle. The number and length of the strokes can be varied to suit the different widths of boards. A somewhat novel feature has latterly been introduced in this class of cross-cut bench-we believe by Messrs. A. Ransome and Co., London. It consists of a self-acting stop, which can be set to gauge any required length of board. This stop is brought into position when the saw is retiring after making its cut, and moves out of the way as it advances, so as to allow the boards sawn at the last stroke to fall out of the way immediately after they are cut. For cross-cutting heavy scantlings, deals, &c., various modifications of ordinary saw benches are introduced, the saw, by suitable gearing, being made to advance through the wood and retire to its first position ready for the next cut; these modifications vary according to the size and class of work to

be done.

For

As a rule, it must be considered preferable for the saw to be made to pass through the wood, instead of the wood being pushed through the saw. sawing railway sleepers, benches are generally arranged with an endless chain, working on rollers of corresponding pitch. This chain carries loose' dogs,' which grip the end of the timber. As each sleeper is sawn, the 'dog' is removed, and placed at the end of another log; a continuous feed is thus obtained.

In small establishments, or when constant changes are made in the work, a ripping and cross-cutting saw can be combined in the same bench by mounting two saw spindles in a revolving frame placed beneath the bench, which can be moved round by a hand wheel and worm gearing, thus bringing into operation above the level of the bench either the cross-cutting or ripping saw, as required. Saws of small diameter can be driven by friction discs. When much light wood has to be cut to a certain length, as in box-making, a convenient plan is to mount the saw in a slide which can traverse backwards and forwards through the wood by a hand lever, an uniform tension of the belt being secured by passing it over pulleys fitted in a vibrating or pendulum frame. For edging purposes

three or more circular saws can be mounted on the same spindle, and a horizontal roller-feed attached. Both the feed and saws should be made adjustable for different thicknesses or widths of wood by worm or rack and pinion gear. The feed rolls can be driven direct from the saw spindle.

For grooving and rebating purposes the saw spindle runs in bearings fixed on a slide working in a bracket, bolted to the under side of the bench; thick

saws of about 12 in. diameter, varying according to the width of groove to be cut, are used in place of the ordinary ripping saw. By means of a hand wheel and screw, the slide can be raised or lowered for the saw to project above the surface of the bench the exact depth of the groove to be cut, and the wood is passed over it in the usual manner. Benches are also fixed on wheels for forest use, or where they have to be constantly moved from place to place, and are often otherwise varied in their constructive details to suit special conditions or circumstances.

Where many rough and irregular logs have to be cut into boards or scantlings, the roller feeds are illadapted for the purpose. This, however, is accomplished by rack or drag-rope benches. Fig. 3 illustrates a well-designed sample of the ordinary drag-rope bench, made by Messrs. Johnstone, Hewetson, and Wilson, London. These benches are adapted to carry saws up to about 54 in. diameter; after this size, the rack bench is to be recommended. The illustration needs very little description. The framing is of the now wellknown box' form; the bearings are let in from the top of the bench, and are so divided that by means of set screws they can be set up' and adjusted to equalise the wear of same. An arm cast with the bench carries the bearings outside the driving pulleys; the rate of feed can be varied by means of the cone pulley and belt underneath bench. For bringing heavy timber up to the saw, carriages running on rails are used. The fence is fitted with binding roller and weighted lever for keeping the wood close up, and the width of cut is easily adjusted by means of a transverse screw placed within the framing. In circular saw benches