RE: [CAD_CAM_EDM_DRO] Bent Nook ballscrews ?????

On Mon, 2003-08-11 at 11:31, Dan Mauch wrote:
> I while back I posted some results of testing the lead accuracy of the
> Saginaw ball screws in my mill/drill. I was surprised to see a pitch
> error of .002 in one inch. It was only at one place. The rest of the
> ballscrew was pretty close to being spot on but that .002 was surpising
> in one inch.

When we powered up the servos, we tested travel on this axis
thoroughly. The travel distances were extremely accurate in the areas
and travels we tested. We used both 0.001" and 0.0001" dial
indicators.

> You may want to try manually turning the ballscrew over
> it's entire length to see if the jamming is in one spot or in several
> places, then adjust for the tight spot or install a spring loaded
> compliant nut.

Spring compliant nuts are a total NO NO. With the forces involved with
a ball screw setup, they do NOT keep the ball nuts preloaded.

If there is a pitch problem, we might have to adjust the ball nuts
slightly loose. Thus far I am pretty certain it is a bent screw issue.
The ballnuts get tight for 1/2 a revolution and then loose and then
tight, etc.


> Dan
>
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