Re: rolled ball screws

Greg,

The bottom-er line is that if you have a non-compliant spacer between
two nuts on a rolled ballscrew, you will then USE the yield value of
the bearings and races themselves to accomodate the inherent lead
innaccuracies.

Which is a BAD thing! VASTLY reduced life, uneven motion (or even
locking up), and possible catastrophic failure are all possible
consequences...

What CAN work with rolled thread, is to slightly oversize the balls.
Dan Mauch first made me aware of the possibility, and it works.
Single nut (cheap), oversize balls (cheap,but hard to find), and time
spent reloading, and you've got a solution.

If the balls are TOO oversize, you're right back where i started
above. But if you get the size right, and let themn "work in" a bit
before asking for full load and quick traverse; the slight burnishing
of the rolled thread and nut actually helps seat the two parts
together. Shorter nuts are better for this technique, which means it
is not suited to high loads. Dan and I used it in mill/drills,where
it works well.

Hope this helps,

Ballendo

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Greg Jackson" <greg@t...>
wrote:

<snip>

> Bottom line is that a stiff system between the nuts allows for

longer life

> on the ballscrew without the risk of the working load overcoming

the nut

> preload system.
>
> Greg
>