It is unprecedented for me to post twice in an evening, but the Computer table needed a finale. So I finale-d it.
So we are back to the dividing head. The critical part of this is getting the angles right, so that the gears will mesh.
My original idea was to make the support post vertical. Then I had to measure the angle at which the shaft hole would be drilled. This was very difficult. The thing is very small and really there are no reference surfaces.
While I was at it I decided to add a right-side support. This is to keep the worm from going forward, instead of turning the gear. I clamped it up and was able to drill the holes -- but in the wrong places! I had drilled and tapped the hole for the worm end in the wrong place :((. I rescued this with a plain old 10-32 screw. I can adjust this screw to compensate for the "endshake" (as we clockmakers say) in the worm. It is unsightly but it works.
The sector arms must be locked in place once you have determined the spacing of holes. This depends on the number of teeth you are going to cut. Simple, I said. Just use a couple setscrews. Yes, but the setscrews push the sector arms apart! Aargh! I should learn General Relativity instead of this machine shop biz. However, a spring load on the sector arms should do it. So I found a suitable spring (I hope) in my odds and ends bag, and now I have to machine a suitable spring-hold-downer. This is a job for the Taig:
I have a piece of scrap in the Taig chuck; I am machining the thing to two diameters, one to fit the crank and one to push down on the spring. I will use a setscrew to hold this thing down on the shaft, maybe a spot of Loctite, too. I have cross-drilled the thing,. Tomorrow, tap it, file a flat on the shaft. There are lots of things to be done yet, but I have made progress. Sufficient unto the day is the evil thereof.