On Tue, 16 Aug 2011 09:32:29 -0500, "Pete C."
wrote:


"Lloyd E. Sponenburgh" wrote:

I'm doing a cnc conversion on a 13x40 gearhead lathe.

My Z servo will be belt driven, so I think I can handle that.

Do any of you have a recommendation for a zero backlash coupling for the X
drive, which will be direct?

(metric AC servos)

LLoyd

That depends on how accurately you can mount the servo. The big CNC
machines I used to work on had rigid couplings with precisely located
motors. For a retrofit you are probably looking at a coupling that will
accommodate some misalignment. I'd look at the helical couplings or the
flex disk couplings. I wouldn't even consider anything like the lovejoy
or similar with any sort of insert.

Try Mcmaster.com, flexible shaft couplings, catalog page 1165.

Hmm. I like the lovejoy for retrofits. Easy to disassemble. The only
possible solution on a couple locationsI've had. I suppose a purist
would say there's an RCH of backlash in them. IMHO, a tinsy fraction
of the total system backlash. I suppose if your building parts for
NASA or Medtronic it might not be good enough.

Just my 2 cents

Karl