This is a lathe fixture for replacing broken teeth on a brass clock wheel. The fixture permits you to make slits in the rim of a gear where once dwelled whole teeth. Into these slits, solder new teeth and then use a file to put on the proper tooth-tip profile.
The wheel is indexed by a spring-loaded detent, seen to the left of the gear, when there is more than one tooth to replace. The whole teeth provide the proper indexing interval.
The wheel is held down by a finger clamp
The one-piece spring and detent as well as the clamp are made from 1/16" gauge plate (flat tool steel). The narrow springy part of the detent has been hardened and tempered to blue. The parts are made by sawing them out with a jeweler's saw, using a pattern. The knob on the detent is made from brass, and is riveted on the spring detent.
The clamp and the detent spring are bolted to the bed through slots, with one bolt each. This permits adjustment for varying-sized wheels as well as tension on the detent spring and clamp. The clamp has a 2-26 set screw in its tail, to provide clearance for the material of the wheel.
The saw is an ordinary slitting saw, available from toolhouses. These saws are available in diffent widths. You can also move the lathe carriage a bit left or right to widen the knotch, making several passes into the wheel to do it. The depth of the sawcut into the wheel is controled by the lathes' crossfeed knob, seen below.
The wheel mounts on a washer, especially sized to its bore. The washer screws onto the base plate with a tapered (flat head) screw. The fixture is held up by an adjustable post, which slides down into a hole in a slitting saw table which is bolted to the cross-slide of the lathe. The hole for the post is on the right of the 1"x1" aluminum block.
The post is riveted onto the base plate. There is a set screw on the left end of the block (not visible).
