On Tue, 16 Aug 2011 13:02:19 -0500, "Pete C."
wrote:


Ned Simmons wrote:

On Tue, 16 Aug 2011 11:21:27 -0500, "Pete C."
wrote:


Ned Simmons wrote:

On Tue, 16 Aug 2011 07:36:23 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com 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

I like Oldham couplings for this sort of thing. They're much cheaper
than higher performance options like bellows couplings, less fragile
and cheaper than helical beam couplings, and usually good enough in
all but the most demanding motion control apps. McMaster has a limited
selection; Lovejoy and Huco have much more. Lovejoy has some
comparison info in their catalog.

http://www.lovejoy-inc.com/products/...couplings.aspx

Those are not zero backlash couplers. McMaster has zero backlash
flexible couplers specifically intended for servo use. They aren't
particularly cheap, but if you only need one of them they should be
acceptable.

The Oldham couplings from Huco and Lovejoy are zero backlash,

The link you provided does not indicate the Oldham style is zero
backlash. The only three piece coupler on that page indicated as zero
backlash is the curved jaw GS series.

You're right, it doesn't say so specifically, but the page also
neglects to specify that the bellows coupling is zero backlash.

Here's Huco's description:

"Rotation is transmitted through a central disc that slides over the
tenons on the hubs under controlled preload conditions to eliminate
backlash."

http://www.huco.com/products.asp?cat=57

--
Ned Simmons