Re: leadscrew bearings / machine design(2nd gif dwg)

Wally:

I believe the lead should be in tension. It's a column buckleing
issue. All should keep in mind: no scale was implied in the stackup
layouts. By definition, the further apart the bearings are, the more
stable the installation will be...and the thicker the lead/support
plate. The one advantage to the B method of using two bearing
retainer plates is the increased distance between the bearings, for a
given thickness of support plate. The disadvantage is the counterbore
required to engage the inner bearing's outer race.

The disproportionate scale results from never having seen one :)

Ron

--- In CAD_CAM_EDM_DRO@egroups.com, "Wally K" <cnc4me@u...> wrote:
> Jan:
>
> I would like to know more about your ballscrew mounting methode.
> Instead of getting very wordy, is it like methode A, B, or, C. In
> the drawings stackup2, and 3 gif, but with more distance between
the
> bearings. Also i am getting confused if a ballscrew is supposed to
> be held in compression or in tension.
>
> Wally K.
>
>
> --- In CAD_CAM_EDM_DRO@egroups.com, JanRwl@A... wrote:
> > 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.!