The most essential part of this tool is the threaded screw B, which acts as a rack, and the worm-wheel, solid with the dial C.
The worm-wheel which meshes into this screw is solid with the dial, as shown at C.
The cam c to be cut is bolted on to the face of the worm-wheel, which faces the headstock of the lathe.
It may here be shown that a worm-wheel may be made to work correctly with a square thread.
This worm-wheel is made in two parts screwed firmly together.
The cutter worm acting as a screw causes the worm-wheel to rotate upon its axis, and therefore to feed to the cutter.
Upon the opposite end of the shaft is the worm-wheel in the process of cutting.
In addition to this two stationary supports may be placed beneath the worm-wheel (one on each side of the cutter).
At the end of d′′ is fixed, in the usual manner, the worm-wheel for the dividing mechanism.
The live spindle is driven by a worm-wheel, provided around the circumference of the face plate.