[Fig. 82]. Wabble Saw.—This is a most simple and useful tool, as it will readily and quickly saw out a groove so that it is undercut. The saw is put on the mandrel at an angle, as will be seen, and should be run at a high rate of speed.
[Fig. 83]. Crank Motion by a Slotted Yoke.—This produces a straight back-and-forth movement from the circular motion of a wheel or crank. It entirely dispenses with a pitman rod, and it enables the machine, or the part of the machine operated, to be placed close to the crank.
[Fig. 84]. Continuous Feed by the Motion of a Lever.—The simple lever with a pawl on each side of the fulcrum is the most effective means to make a continuous feed by the simple movement of a lever. The form shown is capable of[p. 76] many modifications, and it can be easily adapted for any particular work desired.
[Fig. 85]. Crank Motion.—By the structure shown, namely, a slotted lever (A), a quick return can be made with the lever. B indicates the fulcrum.
[Fig. 86]. Ratchet Head.—This shows a well-known form for common ratchet. It has the advantage that the radially movable plugs (A) are tangentially disposed, and rest against walls (B) eccentrically disposed, and are, therefore, in such a position that they easily slide over the inclines.
[Fig. 87]. Bench Clamp.—A pair of dogs (A, B), with the ends bent toward each other, and pivoted midway between the ends to the bench in such a position that the board (C), to be held between them, on striking the rear ends of the dogs, will force the forward ends together, and thus clamp[p. 77] it firmly for planing or other purposes.
[Fig. 88]. Helico-Volute Spring.—This is a form of spring for tension purposes. The enlarged cross-section of the coil in its middle portion, with the ends tapering down to the eyes, provides a means whereby the pull is transferred from the smaller to the larger portions, without producing a great breaking strain near the ends.