Machines for tenoning heavy spokes have two cutters, the upper with a vertical adjustment, to regulate the thickness of the tenon. The lower head is stationary, the table adjusting to regulate the depth of the cut on time under side. There is provision for cutting shoulders of unequal lengths and for their accurate separate adjustment. The spoke is held in a carriage, which travels in a horizontal plane, being attached to a vibrating lever pivoted below. For making blind-slat tenons in large quantities there is employed an automatic blind-slat tenoning-machine which feeds the stuff (of any length desired) endwise through radiating chucks, the shoulder being pressed against an adjustable gauge for regu lating the slat length. The cutting-tools make two tenons at once and cut off the piece with one cutter-head. The slat is rotated, so as to make a more perfectly cylindrical tenon. To avoid splintering or tearing, the cut is from the outside toward the centre.
Tenoninachine. —For cutting car-sill tenons it is desirable to complete each timber without reversal, and for such work a double platen machine has been produced (fi/. i6, fig. 3), which will cut single, double, or triple tenons on both ends of a long timber, from one face, with out turning it end for end. This is done by moving the stick into the proper position on the first platen, securing it, and traversing the heads down by the hand-lever, thus finishing the tenons on the first end ; next moving the timber forward on to the other platen, past the heads, until the opposite end is in position, and then traversing up the heads, thus cutting the tenons on the other end and leaving the heads in position for traversing clown for the first end of the next sill. In this machine no side cutters are necessary for making double, or even triple, tenons; the heads, instead of the work, traverse, and the cutter-head arbors are at right angles to the length of the stick and parallel to its width, while in most machines there are used for single tenons two cutters parallel with each other and with the length of the stick, as in Figure 2, there being neces sary for double•tenoning with these a third cutter, haying its spindle at right angles to the other two and to the length of the stick.
The "Gap" is so called because of its frame, which is of the goose-neck type and has a deep gap formed across the column, for the passage of the timbers end-wise between the cutter-heads. The sole-plate or bed is similarly "gapped." Ilheel-lenoning work is referred to under wheel-making machinery.
/nrising is done by chisels and gouges used in the hand (usually with the aid of a mallet) or in mortising-machines (which both incise and bore). Their cut is generally crosswise of the grain, and chips are the resultant waste. Figures 29 and 3o (II. 13) show hand-chisels; Figures 31 and 32,
gouges; and Figures 6 and 7 (p1. 16), mortising-chisels for machines.
Moilising-machines.—The days of hand-made mortises are nearly gone, for two reasons: first, there are fewer men competent to do the work properly by hand; secondly, machines are made which do better work at far less cost and in a small fraction of the time. It might be added that mortised construction is less common than formerly, because (I) so many wooden houses are made with " balloon frames:" (2) bent wood is used for chairs and in car-, carriage-, and wagon-work; and (3) straight sticks fitting in sockets are largely used in freight-car construction.
In one class of mortising-machines the chisel-bar has a positive con tinuous movement and the work is raised and lowered to the chisel to receive its action. These are simple, fast-running, and well adapted to light work. In a second class the mortise is formed by a revolving traversing auger or bit, which cuts on the side as well as on the end. In a third class the bar carries a hollow chisel and anger, which has a pro gressive forward movement to the regular depth of mortise, the action of the anger preceding that of the chisel and making a mortise its full size at each forward stroke. This class works best in heavy timber. A fourth class has a graduated stroke, starting from a still point, and increased by lengthening the connection from the eccentric or other driving device to the chisel-bar. This graduated chisel-bar movement is generally effected by having between the connecting-rod, which is attached to the driving crank-pin, and the top of the chisel-bar (which latter has only a recip rocating movement) a double link one-half of whose lower end is attached to the chisel-bar and the other, directly in the same central line with the wrist-pin, to a lever, which permits of throwing it out of line with the bar. When it and the chisel-bar are in the same straight line, the latter has a maximum stroke, but by practically bending the chisel bar at the top this stroke may be reduced to nothing.
Foot-mortisers work upon still another plan, the work being held and the chisel brought down by a treadle and suitable levers to any required depth. In the best makes this leverage is such as to form a knuckle joint, thus giving greater power as the tool gets into the work. The tool is brought back by a spring. In all machines having a reciprocating chisel the tool should reverse automatically while the machine is in motion. The bed carrying the work should swing to any desired angle about an axis at right angles to the length of the piece and to the stroke of the chisel. In mortising-machines of the best form the bed is provided with both power- and hand-feed.