WOOD-WORKING MACHINERY. Under this head may be embraced the various machines by means of which lumber as cut in the forest is reduced to standard dimensions and then made into pieces ready for immediate use, sue!' as boards, trim, doors, sashes, boxes, Pte. As the lumber advances throngh consecutive operations the machinery employed lassaues more and more specialized, and many ingenious and involvesl ma chines such as those for making barrels, wheels, chairs, and other similar objects are required. A general division of wool-working tools may lie made into those operating (a ) by scission or cleaving, such as saws of various kiwis; (b) by paring, as the planers, surfacers, matchers, etc.: (c) by combining the two foregoing principles, as in the case of lathes, boring machines, Itliurtisers, and gaining machines; (d) by abrading or grind ing, as sandpapering and similar finishing ma chines.
Considering now a few essential forms of wood working machines more specifically, we have first the saws, which are discussed under that head, but which may briefly be considered here. Rather than have the forest lumber cut by the log saws, it is preferable, for reasons of economy, to have it squared and then resawed at the mill. For this purpose vertical reciprocating saws, eir cular resaws, and band resaws are'employed. The latter saw's are finer than the log saws and con sequently avoid unnecessary waste. They cut the lumber into large planks or boards. To reduce the lumber to the desired dimensions circular, ripping, and cross-cut saws are used. The for mer have fewer and larger teeth, which cut upon their front edges, while the latter cut upon their sides. in using the ripping saw the boards have to be fed to the saw, but with the cross-cut saw it is possible to move the saw to the work. Many forms of circular saws are devised by varying the arrangement of the carriage, and shingles, clapboards, and other products, more or less ir regular in form, can be prepared.
For curved and scroll sawing a narrow hand saw is employed, though there are reciprocating jig-saws suitable for this purpose.
After the wood conies from the saws with its rough surface it nmst next he surfaeed, or smoothed and planed, to the required dimensions. In the surfacer this is done by a series of revolving cut ters. These cutters pare off shavings, leaving the board or beam quite smooth. In many of the surfacers all four sides of the board are operated on at once, in some cases the tongue and groove being cut in the edges. The number of knives in each cutter may vary from three to nine, and the machines are fitted for handling various sizes of stock. instead of plane surfacers machines may
he devised for cutting curved surfaces to a given pattern, as in the case of molding, while there are numerous cutting which carry cutting tools on a vertical spindle, enabling scrollwork, carving, paneling. etc., to he done. Of consider able importance are the dovetailing machines, which may consist of either a gang of chisels or of a cutter similar to that of the carving ma chine, which cuts out the tongues and spaces, automatically spacing them, so that an exact fit is assured.
Lathes are an important and much used class of tools. In them a piece of wood is rapidly re volved while a chisel or other tool is held against it, with the result that the wood is removed by a combined action which involves both the severing of the Mats and paring. Many forms of simple wood-turning lathe exist, and the machine, when operated by a skillfUl mechanic, is capable of a wide range of work. By using various automatic att:tehments, however, the output of the lathe can be increased. especially where a number of similar pieces are to be constructed. In the simplest of these processes the cutting tool fol a pattern. which regulates the depth of cut. and consequently the radius of the turned object. Then there is also the Blanchard lathe, with its many modification:. where the blank and a pat tern are revolved and rotary cutters carve out of the former an exact facsimile.
There are also lemming machines to make tenon joints, and !joining machines, which cut grooves the surface of timber, while to make mortises to receive the tenons there are ma chine:, some of which have rotary cutters and others reciprocating chisels. Of boring machines there are numerous designs. arranged specifically for a given class of work.
brasiro machine-s include sandpapering ma chines. where an endless belt, on which sand or emery has been fixed, is in contact with the work, and drum machines. where the work is a large flat surface.
With slich tool, as those outlined many va rieties of work can he performed, and where a large number of pieces of a particular clan, of work are desired, a special machine is construct ed which turns them out more or less automati cally. It is in this direction that the greatest in wood-working machines are be ing made. Their efficiency, as well as their eapability for rapid work, is also being constantly augmented. See BUILDING; BORING MACHINERY; SAW; SAWMILL.