Spher′i-cal saw.
An annular saw, as the trephine.
A,
Fig. 5377. This usually has a guide-point
a at the end of a rod, secured by a set-screw
b, and passing through the tubular stem of the saw. See trephine.
B is a crown saw. These are sometimes as large as 5 feet in diameter and 15 inches deep.
In this case the saw is built up of three or four thin plates of steel bent to form portions of the circle, and riveted to an annular ring, which is fixed to the surface chuck of a kind of lathe mandrel by means of hook-bolts
h; the work is grasped in a slide-rest, which traverses within the saw and parallel to its axis.
i is a rough sheave cut by the crown-saw;
k, a brush back;
l, wheel-felly; and
m, a chair-back, cut by the oblique action of the saw.
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Spherical saw. |
A saw of a dished shape, the segment of a sphere, has been used for sawing curvilinear work.
The fence was made as the arc of a circle, and had a conductor to receive the work.
The circular fence was attached to a three-bar parallel rule, so as always to keep the curvatures of the fence, conductor, and saw parallel with each other.
