I've been thinking about making a 10" rotary table for a cnc router to be able to do pearl inlay on large vessels and banjo rims. The table would be made of aluminum jig plate. Cutting forces would be minimal, and speeds relatively low, but it needs to have absolutely minimal backlash. Wondering the best way to accomplish this?

So far I'm thinking yo use a large cross roller bearing to support the table, found a used 8" diam one on ebay cheap. If you aren't familiar with these, google it, they are very cool.

I saw an earlier thread about using a harmonic drive to make a backlash free rotary, and that seems like a possibility. I can find them on ebay, but they are pretty small relative to the 10" table, and I'm wondering if they will work for small increments of motion at the periphery of a 12" diameter or larger object. If I want to move .002", that comes out to .019 degrees. If use a 150:1 reduction drive with a 200 step/rev stepper, that's 30,000 steps/rev. Which gives me about 1.6 steps for .002" travel at the circumference. Seems reasonable

Am I thinking correctly here? Supposedly harmonic drives have zero backlash, so this should work, yes?

Other possibilities are to use a worm gear drive, or a timing belt drive with several reductions. Not sure I could avoid backlash with these methods and keep the gizmo light and compact.

The harmonic drive seems like an elegant solution, plus I like the idea of using such an exotic item.

Edit - corrected math, was off by a factor of 10, sorry