Re: [CAD_CAM_EDM_DRO] SeriesII Quill Zaxis CNC addon ideas: Like JonE's?

Dan,
Thanks for the comprehensive input. My Enco mill is not quite that
heavy, but I was concerned about moving the knee up an down. Was the 4th
axis on that Tree Mill the quill? My biggest concern is motorizing that,
with positive control.

Marv Frankel
Los Angeles

----- Original Message -----
From: "Dan Mauch" <dmauch@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Friday, November 22, 2002 6:59 AM
Subject: RE: [CAD_CAM_EDM_DRO] SeriesII Quill Zaxis CNC addon ideas: Like
JonE's?


> I have to jump in here.
> I recently helped a customer put a 4 axis servo system onto a Ebay
> purchased 3500# Tree Mill which is probablty equivalent to a series 2
> mill. The machine as purchased had beautiful ballscrews with zero
> backlash on the XY axis. The knee was driven by a AC servo motor mounted
> onto a 5:1 gearhead driving an acme leadscrew. It was obvious that the
> machine had seen a lot of use but was in near perfect mechanical
> condition. The A/C servo controls were dead. During the retrofit we
> simply replaced the existing servo motors with ones compatible with the
> G320. It was really simple . Unbolt the existing motors and replace it
> with a standard servo motor with a 5/8" shaft. It used a 2/1 ratio
> timing belt/pulley. After it was changed over the only problem we ran
> into was that for some reasons the calculated size of the motor for the
> knee proved inadequate so we replaced the Z motor with a larger motor.
> It ran beautifully with a low (50)cpr encoder on the knee servo motor.
> From what I could see that machine must have had many thousands hours or
> use and yet the acme leadscrew on the massive knee, with no other
> assistance, seemed to be in good condition as we never did see any
> backlash or slop in the knee. The guy is currently using it to make
> parts. I can see no reason why driving the knee will cause him any wear
> concerns.
> Dan
>
> -----Original Message-----
> From: Marv Frankel [mailto:dcdziner@...]
> Sent: Friday, November 22, 2002 12:46 AM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: Re: [CAD_CAM_EDM_DRO] SeriesII Quill Zaxis CNC addon ideas:
> Like JonE's?
>
>
> Tim,
> Thanks for pointing out the screw wear problem to me. I hadn't
> even considered it, but it makes sense if you think about the constant
> up-and-down in almost the same area on the screw. I was pointed to some
> pictures the other day, at http://www.motovidia.com/MILL%20pics/, which
> showed a Z axis knee, with a ballscrew, and to keep the knee from
> falling through gravity, he had to mount a 150 lb. gas spring from the
> knee to the base, to balance it. I wonder if the tendency of the knee to
> fall, can be overcome by using a ball screw with a greater number of
> TPI?
>
> Marv Frankel
> Los Angeles
>
> ----- Original Message -----
> From: "Tim Goldstein" <timg@...>
> To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> Sent: Thursday, November 21, 2002 4:43 PM
> Subject: Re: [CAD_CAM_EDM_DRO] SeriesII Quill Zaxis CNC addon ideas:
> Like Jon E's?
>
>
> > Marv,
> >
> > The only downside of doing it with an acme screw is the wear. Carrying
> that
> > much weight and moving it all the time will likely yield an
> > inconsistent pitch in a relatively short time. Besides, on my machine
> > it was already equipped with the ground screws from the factory.
> >
> > Tim
> > [Denver, CO]
> > Sherline products at Deep Discount (now Mach1 CNC controller too)
> > www.KTMarketing.com/Sherline
> >
> > ----- Original Message -----
> > > Tim
> > > If you size your motor properly, with the right gearing, is it
> > really
> > > necessary to convert the knee to ballscrew? It seems to me, with
> > > that
> much
> > > weight on the screw, the original acme screw would have virtually no
>
> > > backlash. Gravity would take care of it. If we could figure out how
> > > to
> put
> > > the same amount of tension on the x and y axes, we would probably
> > > never
> > have
> > > to concern ourselves with their backlash. Aren't we doing almost the
> same
> > > thing with pre-loaded nuts?
> > >
> > > Marv Frankel
> > > Los Angeles
> >
> >
> >
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> OFF Topic POSTS: General Machining
> If you wish to post on unlimited OT subjects goto:
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> if you have trouble.
> http://www.metalworking.com/news_servers.html
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> http://groups.yahoo.com/group/jobshophomeshop I consider this to be a
> sister site to the CCED group, as many of the same members are there,
> for OT subjects, that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM.
> DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........ bill
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> OFF Topic POSTS: General Machining
> If you wish to post on unlimited OT subjects goto:
aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if
you have trouble.
> http://www.metalworking.com/news_servers.html
>
> http://groups.yahoo.com/group/jobshophomeshop I consider this to be a
sister site to the CCED group, as many of the same members are there, for OT
subjects, that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM.
DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
> bill
> List Mom
> List Owner
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>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
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