The bench shown at Figurer serves to secure the piece to be smoothed. To a thick hard-wood slab are fixed two parallel jawed wooden vises, one or the other of which is used as needed.
for planing or smoothing " timber," as the English call it, or " lumber," as the Americans term it, work princi pally with rotating cutters, although some employ stationary blades like plane-bits, as shown in Figure 34, where three such bits are used. Ro tating cutters generally have their axes parallel to the plane of the surface to be produced, and of these some use straight and others spiral blades. Most of those using straight blades are set at right angles to the direction of the feed, though some are set diagonally. Those using straight blades and having the axis of the cutting-cylinder at right angles to the bed usually have the blades so set as to cut with the entire length of each at once, though sonic have the blades so set as to produce a shear ing cut, thereby simulating the action of spiral blades.
Where there is desired greater accuracy of surface than can be pro duced by rotating cutting-blades parallel with their arbor, spiral blades are sometimes used, although they are not very generally known. They are sharpened by means of a broad-faced emery-wheel, the blades and their arbor being mounted in rigid bearings, and the wheel having, in addition to its rotation, a traverse motion exactly parallel to the axis of the cutter shaft journals. The spiral-bladed heads have the twist run from one end toward the other, not from the centre both ways, and the cylinder is placed at right angles to the passage of the material. Rotating cutters, which have their axes vertical and at right angles to the surface to be produced, have as cutters bits which are set either in the face of a disc or at the ends of opposite arms at right angles to the axis of the head. Although most wood-planing machines have their cutting-cylinders at right angles to the feed, some have diagonal cylinders, as in Figure i (p. 14). Sonic single cylinder machines plane the under surface of the stock, working it par allel to the bed; others pass it under the cylinder and work its upper face; and yet other machines may be arranged in either way.
The Dimension Planer has a rotating cylinder which carries two or more knives, either straight or spiral, and the material is fed under this cylinder upon a travelling table. This works but one side at a time, and is generally used for large timbers. It is often arranged to feed and cut
in either direction. In one form of this machine, known as the Daniels planer, there is a vertical shaft bearing a horizontal arm at each end of which there is a cutter. As the shaft rotates the work is fed along under the cutter-arms. Sonic machines for the same purpose feed the material in upon rollers; others have an endless apron. In the Daniels planer the table or bed may be made in lengthwise sections bolted together, so as to give any desired length with the fewest patterns.
In some types the stock can be run diagonally under the cylinder instead of setting the cylinder in a diagonal position, which has the disadvantage of not permitting straight belts to be run to the cylinder. Running the stock in diagonally, however, permits feeding in short stuff. A matcher-head which does good work has four sides, as in an ordinary cylinder-head, but each is fitted with a bit milled out on both sides, thereby throwing the cutting-edge to the centre of the bit, with the object of pre serving the cutting-edge as long as possible. The heads are of gun-metal and the slots for the bits are milled in and dovetailed, the bits being held in place by steel studs.
The S aning Alachine(pi. I 3, fig. 34) has three plane irons, in working which the lower side of a board runs over the edges of three plane-irons, each of which detaches a broad shaving, while the upper side of the board rests against stationary rolls. The bits extend the entire width of the board, this being permissible on account of the softness of the material. The board is fed forward by the motion of smooth or fluted cast-iron rolls arranged in pairs front and back of the bits. Machines of this kind are used for smoothing boards and posts as well as for cutting very thin boards for the manufacture of boxes, etc. Steaming the wood renders it extremely soft and permits giving great width to the bits, so that such a machine can be advantageously substituted for a veneer-saw, there being no loss from sawdust. In some very large machines for rough work upon frozen pine and the like the machine has several stationary plane irons, which take off rong-li cuts before the rotating- cutters strike them. One Norwegian machine takes from twelve to fourteen successive cuts from a board at one pass. The machine shown in Figure 34 (pl. 13) has also revolving cutters for working the edges of the boards.