Thanks!
when faced with using 3 phase equipment in home shops, many hobby machinists make rotary phase converters from surplus 3ph motors, others convert to a dc motor and run it with a VFD, this gives variable motor speed. I've never done this myself though, all my machines are single phase.
I think a disc is better than a belt for this apllication because
1. Discs are cheaper and easier to change than belts.
2. Belts always have a seam or joint. I think the "bump" every time the seam comes around would be less than ideal for this kind of precision work.
There are probably some instances where a belt is the only way, such as certain crown guards, but I haven't encounted these yet. I'll deal with this when the need arises. It may be possible to accomplish the same thing by adapting an old jigsaw or die filing machine.
I buy psa film discs from Amazon, I'm happy with them so far. I also have a 3000 grit diamond lapping disc on its way to try. You can also order lapidary abrasive discs graded in microns, but I haven't worked out exactly what grades I'll need yet with this system, being unfamiliar with it.
Here's what I bought to start
http://www.amazon.com/SUNGOLD-ABRASIVES-74623-6-inches-Assorted/dp/B00HNDMAMS/ref=pd_cp_hi_0
The rotating spindle jig rides in bronze/Teflon bushings, to allow rotation and linear motion. It can be moved relative to the abrasive disc wth the carriage and crossfeed. The spindle housing is attached to its mounting post by way of a shaft clamp collar, so it's height-adjustable and can rotate around the mounting post also. So it can be adjusted in all 3 axis, and to any vertical or horizontal angle. I don't have any indices or degree wheels on any of this, I'm more of an eyeballer. I think it would just slow down the setup, and not really add any useful improvement to the finished result.