Re: [CAD_CAM_EDM_DRO] re:Lathe Rack & pinion.

Chris;
why don you put the ball screw on the other side of the carriage?
you could fix the bearings on a couple of clamps at the very beginning and at
the very end of the bed ,that way you will have a manual machine as well and
the lathe wont have to be modified
regards
mariano


Chris Hellyar wrote:

> OK, This is a bit larger than a taig though...
>
> I'm actually going to be up against this question myself sooner or later.
> I've got a new lathe (brand new and shiny) in the garage now, which I've
> bought to make the parts for my router.. This may seem a little over the
> top, but I did have access to a lathe at a friends place, but he's moved,
> and it's 50k's to the next nearest lathe I can use... Too much hassle, and
> it was a good excuse to buy a larger lathe than my wee "cnc" job.
>
> But I digress...
>
> The cross on the lathe will be fine to convert, very conventional threaded
> rod into a split brass or similar material nut which is "pressed" to take
> out the backlash. For that axis we can just put a toothed pulley on the end
> of the screw and away we go....
>
> The carrige however has a huge lump of mechanisim on the apron which means a
> second leadscrew is out, and the existing one is captive at both ends in the
> castings by some magic method of assembly. Without major work I can't see
> how to get a backlash free drive onto the screw. Not to mention the fact
> that the threading leadscrew is a typical interrupted acme thread job for
> driving the powerfeed, and the split nut has heaps of friction so probably
> wouldn't do the job too well.
>
> I think if I did mine I'd just rip out the leadscrew and most of the apron
> mechanism and put a new acme screw in there, but on the lathe I looked at
> the owner wants to keep all of the manual functionality.
>
> Cheers, Chris.
>
> * Design engineer, Assembly worker, Cleaner.
> * Ohmark Electronics. PO Box 5302, Christchurch, New Zealand.
> * http://www.ohmark.co.nz
>
> ----- Original Message -----
> From: <ballendo@...>
> To: <CAD_CAM_EDM_DRO@egroups.com>
> Sent: Sunday, November 12, 2000 1:09 AM
> Subject: [CAD_CAM_EDM_DRO] re:Lathe Rack & pinion.
>
> > Chris,
> >
> > I've seen a Taig lathe CNC retrofit that used the rack. The stock
> > taig HAS NO leadscrew. Sorry, I don't remember exactly where, it was
> > on the WEB, and recently... Prob'ly bookmarked it, but I'm
> > using "borrowed computer(s) just now.
> >
> > Hope this helps.
> >
> > Ballendo
> >
> > P.S. Call Taig and ask. The CNC stuff is done by the son. Different
> > co. name. The first Taig CNC lathe(by Taig) was the son's. When I
> > heard about it several years ago, I called and asked him how it
> > worked with the Rack drive. He said, "My Dad put in a leadscrew for
> > me"!!
> >
> >
> > > Anyone had any experience doing a retrofit to a lathe and used the
> > >Rack & pinion drive on the lathe apron instead of the lead screw?
> > >I've just looked at a lathe a friend is considering retrofitting
> > >after seeing my wee lathe,<snip>
> >
> >
> >
> >
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