Re: Lathe CNC retrofit

Marcus,

Yes, that was my concern. But also that the saddle structure is
oftened tapered as well. Which means you are "forcing the issue" from
a relatively weak position, irrespective of way construction.

Your solution seems fine, but would present one problem: Won't the
chips be trapped in there with that spinning ballscrew? Some sort of
sliding way covers (between the way covers<G>) seems in order to keep
the chips out...

On a re-read of your post, I may not be understanding your use
of "drawbar tube"; but I think my misunderstanding might only mean
that you have already considered the chips?

Hope this helps.

Ballendo

P.S. For lathe lovers, at the Houston metalworkers Club (the link was
posted by Jan R recently), there is a very interesting article/
project on an "electronic" leadscrew. If yer messin' with lathes, be
sure to take a look, IMO.

--- In CAD_CAM_EDM_DRO@y..., "Marcus & Eva" <implmex@a...> wrote:
> Hi Ballendo:
> Are you concerned about carriage racking with this approach?
> I would assume that this is an issue on any lathe with an
asymmetric bed, ie
> one that has a prismatic way in front, and no contact on the sides.
> I am assuming therefore that it does not apply to square way
machines like
> the small Atlas.
> I've considered dropping a ballscrew in a drawbar tube directly
under the
> tailstock, between the ways.
> Unclamping the drawtube would function as a "quick-disconnect",
allowing the
> lathe to be used manually as needed.
> Can you see any objections to this basic design.
> I had thought to use two manual pulse generators like the
Bridgeport EZ
> Turn, but I'm finding that you really lose the "feel" of the
cutting action
> with MPG's, so a quick disconnect is a better option for me.
> Cheers
>
> Marcus
>
> From: "ballendo" <ballendo@y...>
> To: <CAD_CAM_EDM_DRO@y...>
> Sent: Wednesday, January 30, 2002 1:35 AM
> Subject: [CAD_CAM_EDM_DRO] Re: Lathe CNC retrofit
>
>
> > Smoke, others,
> >
> > Be careful. Most lathes are designed to be driven from the front.
The
> > location of the ways 9vee vs. flat), and the saddle and apron
> > construction are all designed around this assumption (on most
lathes).
> >
> > And Fred is right, there are greater forces acting on lathes than
> > many assume.
> >
> > There have been successful cnc lathe conversions using a rear
mounted
> > screw, so it can be done. But be sure you understand the forces
> > involved and how they relate to one another, and the final results
> > attainable with the converted machine.
> >
> > Hope this helps.
> >
> > Ballendo