Wood-Working Machinery

Band-sawing machines, and to a lesser degree fret-saws have to be utilized to cut straight and curved parts which cannot be dealt with by means of a circular saw. The table, through which the blade runs, may be used either in the horizontal attitude, or canted for bevel cutting. These saws need careful design in order to keep working well; the tension on the blade must be sensitive, and the latter has to run in anti-friction guides above and below the table so as to cut truly.

Planing Machines.

Those which finish sawn material on various faces vary greatly in design. The smallest are the hand feed planers, along the surface of the table of which the operator slides the wood past the revolving cutter-block. For hand ma chines this has to be of the safety type, forming almost a cylinder so that the fingers cannot be drawn into the machine as with the older square cross-sectional shape. A vacuum effect is thus secured by the eccentric formation, leaving a space as marked. This both tends to draw the wood down on to the cut ters and to suck away the chippings. The panel planers or thick nessing machines feed the wood along a table underneath the cut ter cylinder, so that thick or thin pieces may be planed to uniform dimensions. With a second cutter-cylinder below the table each side of the wood is planed simultaneously. And with two extra vertical spindles, each carrying a short cutter-block, the edges of the timber may be treated as well, including tonguing, grooving, moulding, or rebating. Roller feed is applied to these panel machines. The most elaborate planing machines are those for flooring-boards, etc., the big ones having eight feed-rollers to pro pel the timber past the cutters and knives, the latter being of non-revolving class to impart a high finish after the revolving cutters have roughed off the surface. The rate of feed will some times exceed 400 ft. per minute. Machines for smaller dimensions of stuff are also made with four or five cutters, and either sort will do matching on the edges of the timber. The bottom cutter heads are constructed to draw out by means of a heavy slide, so that adjustments and settings may be effected and the head slid back into the working position.

Moulding machines produce shapes, planing all four sides at one pass, and for mass production are built somewhat after the style of the large planing machines just mentioned. The vertical shaper or circular moulder has a cutter spindle standing up from a flat table, and the cutters may be of any desired profile, and will mould either straight, curved, or irregular mouldings. Fences of suitable shape guide the wood. Tenoning machines operate with cutters of appropriate shape, above and below the timber, which is fed along by a carriage. A grooving or drunken saw is often

used : this is a circular saw set askew on its spindle, so that it wobbles and produces the groove. Dovetails are cut in machines of single- or multiple-spindle design. For the first, a pitching ar rangement moves the wood into the successive positions for the high-speed cutter to pass through, and in the second all the dove tails are made at one feed, by the several cutters set at the correct distance apart.

Holes of round, square, or oblong shape are made in the boring and mortising machines. The first resemble drilling machines for metal in general form, but are of rather simpler construction. Mortising may be performed with a reciprocating chisel, which is pulled down by a slide and lever to penetrate the wood ; but the hollow chisel is a faster-cutting tool. This is a hollow tool within which an auger revolves and removes the bulk of the stuff and as it is fed in the sharp corners at the end of the chisel square out the hole. Some machines, such as those for railway carriage and wagon work, have several boring spindles and a hollow auger spindle. Another fast-cutting machine is the chain mortiser. This has an endless steel chain the links of which are formed with chisel teeth, and it runs around a long guide bar that is fed into the wood, the teeth cutting the way before and producing the mortise.

Lathes.

Lathes produce all the numerous turned chisels, some of which are evolved with hand-controlled chisels and gouges sup ported on the hand-rest, others by means of a slide-rest having slides moved with handles and screws. When the contours of articles vary (e.g., those of spokes, pick handles, cricket bats, or gun-stocks) a copying lathe is employed. This carries a model of the piece with one spindle and the roughly shaped wood with the other; the cutting is done by means of a revolving cutter block, and the frame holding this is moved in accordance with the copy, so that the shape of the latter becomes exactly reproduced on the wood.

Sandpapering machines finish wood of different shapes, some against a flat disc, others on an endless band. The drum machines are the largest kinds, for extensive output, and have three drums for successive action. The first has coarse paper, the second finer, and the third finer still with a soft cushion beneath to pro duce a high finish. A brush cleans off the dust.

Woodworking machines are extensively fitted with ball or roller bearings, to enable their high speeds to be maintained without heating and excess consumption of power. The mass of sawdust or chips, which is soon enormous with some machines, has to be taken away by a suction apparatus, as mentioned under FANS.

• (F. H.) WOOF. Another name for Weft: see WARP and WEFT.