I had come to the conclusion that I would have to make something bespoke. The Skyfire one looks good and specs are what im looking for. Guess it will be a pricey.

Why did you discount the harmonic drive?

I do have an optical indexer that I could use to cut a nice accurate gear in steel and then turn the worm in phosphor bronze and make up a spring loaded tooth to take out the backlash

Phill
What resolution do you get out of that set up?