Re: [CAD_CAM_EDM_DRO] Re: Lathe CNC retrofit

Hi Ballendo:
I was thinking of a system similar to what I have seen on some taper
turning attachments where the crossslide nut is attached to a long tube
which can then be clamped to the taper attachment, or to the cross slide
depending on whether you are taper turning or not.
I had thought to rig something similar, so that undoing a single clamp
releases this loooong nut from the carriage.
So the nut looks like a tube with the actual ballnut at the tailstock end,
and the rest just clearance for the screw.
The tube can be clamped anywhere along its length.
This setup makes for a relatively short stroke machine, but for the kind of
turning I do, it's perfect.
I typically need less than 6" of stroke.
I'd probably put a wiper at the back of the tube to keep the chips out of
the screw at the exposed end.
I called this elongated nut a "drawbar tube " because that's what the bar on
the taper attachment is called in some of the machine manuals I've read.
I agree; It is a somewhat confusing name.

I'm thinking of mounting a separate short cross slide on top of the existing
slide with a couple of Jergens bushings or taperlocks as the X axis.
I want a quickly set up and quickly removable setup for formturning profiles
on mold cores and for cavity turning.
I want to avoid all of the setup hassles that go with having to set tool
length and diameter offsets, so it's an advantage to me to have the axes
adjustable and disconnectable.
The other option, of course is to have an X-Z slide assembly that I can drop
in front of the carriage and snug down with a single quick disconnect.
Something like the Omniturn retrofit, but without gutting the lathe first.
Now, should this be a stepper setup or a servo rig??
I need very smooth motion for turning shallow tapers, and I get the distinct
impression, from Jon Elson's posts in particular, that I have a far better
chance of achieving this with servos.
Would you concur??

Cheers

Marcus

----- Original Message -----
From: "ballendo" <ballendo@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Wednesday, January 30, 2002 8:50 AM
Subject: [CAD_CAM_EDM_DRO] 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.