WOOD-WORKING MACHINERY includes the various classes of tools for performing the operations on timber, from the rough log to the finished product, This group of machine-tools differs from those for metal-working in two important particulars. The speeds of cutting the material are relatively much greater, and the methods of holding or feeding it are usually quite differ ent. These facts affect the design of the machines in numerous ways, while the saws, cutters, and knives possess much keener angles than those used on metal. Heavy pieces, such as logs, are held on a carriage or table which provides the means of movement in relation to a saw; in other cases ribbed rollers press against partly finished pieces and feed them along. There is also a good deal of direct hand feeding, with the assistance of fences or guides which keep the wood in a correct path, although much mechani cally operated equipment is now in use.
Several types of machines are employed for breaking down logs. A rapid-cutting machine which is much used, although it is rather wasteful of material, runs a big circular saw ; past this the log is fed by a carriage on rollers, the log being held securely by a set of spiked dogs. A similar style of feed also occurs with the vertical band saws, with a blade thinner than that of the circular saw.
The horizontal band-saw is a very fast-cutting and accurate ma chine, feeding the log by means of a carriage between two up rights up and down which the saw frame may be adjusted to cut successively the several boards or flitches from the log. The width of the saw blade reaches to a foot in the big machines, taking logs to 7 ft. diameter. Another manner of breaking down logs is with the log frame, with a feeding movement between up rights as with the horizontal band-saw ; but the log is divided up by a number of reciprocating saws operated by a crank-shaft.
What are termed re-sawing machines do not deal with logs, but cut up the products from the latter, such as deals and flitches, into boards, etc. Such deal or flitch frames cut by a vertically recipro cating set of saws. For more varied cutting, a band re-saw is em ployed, this having the band-saw running vertically and the mate rial fed over the table by ribbed feed rollers. A like class of feed apparatus is fitted to circular saw benches for re-sawing purposes. Saws for cross-cutting are used extensively, being of circular blade class, and with one saw, or two to cut to definite lengths. The pendulum saws are also utilized for this service, consisting of a frame pivoted from an overhead beam so that the circular saw at the bottom of the frame may be pulled by a hand motion through the wood. For general sawing the circular-saw bench is made in various styles, with a fence which guides the wood. The most complete types are the dimension saws which have a complete system of adjustments to angles and positions, with graduated scales for reading the amount that all sorts of cutting, as ripping, cross-cutting, bevelling, mitring, rebating, grooving, etc., require. Single machines carry one saw, double ones two, for ripping and cross-cutting respectively; either of these can be swung up through the table when required. By the use of a cutter-block on a saw spindle further operations beyond the ca pacity of a saw are practicable.