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

I calculated that my 600 oz in servo motor would have a lifting force
of 2500 lbs but the gecko 320 kept faulting even with the gain turned
up. It may have been also do to the fact that the 600 oz in motor used a
250 cpr encoder so there were an awesome number of steps per in i.e.
250X4X5X10=50000. So I took the shotgun approach and put a 50 CPR
encoder on a 900 oz in motor. It was more than up to the task and as I
recall didn't even get warm. I'm sure the two changes in combination
solved the problem.
Dan

-----Original Message-----
From: vrsculptor [mailto:vrsculptor@...]
Sent: Friday, November 22, 2002 8:22 AM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Re: SeriesII Quill Zaxis CNC addon ideas:
Like JonE's?


Dan,
No disagreement with what you said but there are significant
differences between the Tree's knee and a Bridgeport knee. The box
ways on the Tree's knee are huge and the bearing surface (turcite) is
several times larger than a Bridgeport. It was designed from the get
go to be active. I haven't powered mine yet but plan to soon.

How big a motor did you end up with?

Roger

--- In CAD_CAM_EDM_DRO@y..., "Dan Mauch" <dmauch@s...> wrote:
> 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@p...]
> Sent: Friday, November 22, 2002 12:46 AM
> To: CAD_CAM_EDM_DRO@y...
> 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@k...>
> To: <CAD_CAM_EDM_DRO@y...>
> 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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there,
> for OT subjects, that are not allowed on the CCED list.
>
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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
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