Re: [CAD_CAM_EDM_DRO] Mixing servos & stepper in same system

Tim,
Thanks for your response. I thought I'd be more comfortable using
servos on all the axes. I checked the torque on X & Y, and even with the
acme screws, they are pretty free running with 5 TPI. The Z screw on the
knee has 10 TPI, and using the "fishing scale method" (8 lbs. @ 8"), I
calculated 1,024 oz/ins. I'm planning to buy servos that put out 600 oz/ins
of torque. If I gear X & Y @ 2:1, and gear Z @ 4:1, does that seem to make
sense? Can Mach I software provide the feed and control on Z, and speed
control to the VFD, for various size drills?

Marv Frankel
Los Angeles

----- Original Message -----
From: "Tim Goldstein" <timg@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Saturday, January 04, 2003 10:58 AM
Subject: RE: [CAD_CAM_EDM_DRO] Mixing servos & stepper in same system


> I think you have been given poor advise. If you are going to use servos
> on X & Y than use one on Z also. I had Bridgett set up with XY servo and
> Z stepper for a while as I was locating another servo motor. When I
> switched to a servo on Z my Z feeds increased by 50%. The problem with
> steppers on my Z is that it is geared at 4:1 reduction plus the screw.
> The stepper was always trying to go too fast. If you are still at a
> point you can alter the reduction ratios just set up z with more
> reduction and let those servo motors spin.
>
> Tim
> [Denver, CO]
> Sherline products at Deep Discount
> Mach1 & DeskCNC with credit card ordering www.KTMarketing.com/Sherline
>
> > -----Original Message-----
> >
> > Guys,
> > I'm stilll doing R & D on my system components, and it
> > was suggested that I use a stepper to drive the knee's X
> > axis, rather than a servo, because of the steppers better low
> > speed torque. Is there any problem doing that, or would it
> > accomplish the same thing by using the higher speed servo,
> > and just increase the gear ratio.
> >
> > Marv Frankel
> > Los Angeles
>
>
> Addresses:
> FAQ: http://www.ktmarketing.com/faq.html
> FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
>
> Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@...
> Moderator: jmelson@... timg@... [Moderator]
> URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
>
> 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
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>