Re: rolled ball screws

Hoyt,

Different strokes for different folks...

A coupla differences between my recomendations and your response:

1)Using two nuts costs more out of pocket, plain and simple. This
group is aimed at DIY so the "asm'g" is not that big of deal.
Especially compared to machining the parts to join two nuts! (which
is easier, pouring out some balls and putting new ones in? Or buying
TWO nuts; engineering, buying and making the parts to allow for
preload, and assembling too? Which point you prob'ly will have to re-
load some balls anyway!)

2) the length OF two nuts, PLUS the distance BETWEEN the two nuts,
means that any lead variation will be increased in its effect,
compared to the one nut approach. Which "leads"(pun intended) to the
fact that the yield issue, which you have correctly stated exists in
BOTH cases, is much less for the single nut technique I outlined.

Both Dan Mauch and myself (at least) have done this successfully. I
have also made double nut preloads. I can say that for me, the single
nut is MUCH easier.

Hope this helps,

Ballendo


--- In CAD_CAM_EDM_DRO@yahoogroups.com, Hoyt McKagen <bjammin@i...>
wrote:

> At 04:04 PM 1/27/03 -0000, you wrote:
> >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.
>
> Too harsh. There's always a certain amount of elastic distortion in

any

> material.
>
> >What CAN work with rolled thread, is to slightly oversize the

balls.

>
> This amounts to exactly the same thing. In either cae you're

relying on

> elasticity.
> But putting a spacer into the system is easier than asm,g oversize

balls.

>
>
> Regards, Hoyt McKagen
>
>
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