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

Ian;
I ,completely agree with you on this one,unless that the screw is thinner than it should
in which case it should be supported under tension with two sets of angular contact
bearings fitted back to back
regards
mariano


Ian Wright wrote:

> 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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> Welcome to CAD_CAM_EDM_DRO@...,an unmoderated list for the discussion of shop built systems, for CAD, CAM, EDM, and DRO.
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