"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote:

Ig, I'm having a thought that I can do a really bang-up job on the
precision of my lathe conversion with the most crappy ball screws on the
planet.

I have found some very affordable magnetic DRO scales and readers that
provide simple quadrature output (and a zero index) at TTL levels, and
can be had in both 2 micro-inch and 1 micro-inch resolution for very
little difference in price.

The problem is if there is much backlash in the ballscrews, then you
will get servo "hunting" behavior, and it is pretty hard to get rid of
this. You can set a large deadband, but that is pretty counterproductive,
as it destabilizes the servo loop.

Jon