Re: [CAD_CAM_EDM_DRO] re:Re: leadscrew bearings / machine design(2nd gif dwg)

Hi,

This is an unusual approach which is a bit overkill and, in theory at least,
could lead to problems with binding due to differential expansion. A more
usual approach would be to have two angular contact bearings at one end and
a plain bearing at the other, the shaft diameter at this end being a close
sliding fit in the bearing so that any expansion of the leadscrew relative
to the machine frame (or vice versa) will not cause deflection of the screw.

Ian
--
Ian W. Wright
Sheffield UK

----- Original Message -----
From: <JanRwl@...>
To: <CAD_CAM_EDM_DRO@egroups.com>
Sent: 25 October 2000 05:03
Subject: Re: [CAD_CAM_EDM_DRO] re:Re: leadscrew bearings / machine
design(2nd gif dwg)


> Sorry to disagree with learned wizards, but, though very, very stupid and
> very, very, very ugly, I had been there, done that, and the most-rigid and
> "bestest" way to do the ends of a lead-screw are to have two SEPARATE
> angular-contact bearings on EACH end (total, four per screw!), each pair
set
> at least twice the screw-major-diameter apart (between them), or, at least
> twice major screw-dia. plus one bearing-thickness "on-center". Really!
Just
> havin a pair of bearings with "no" space between them (oh, maybe just a
> spacer between the two inner-races) is no-where NEAR the same as the
> "spaced-apart" pair! Unless you are talking a total screw-length no more
> than, say, ten times the major-dia.!
>
>
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