Re: [CAD_CAM_EDM_DRO] which steppers to buy?

John:

I know some folks think they go too slow, but if you rewire a slo-syn
72hz AC/Syncronous motor that you can pick up for $29.00 at a few places,
you get tremendous strength from them. I don't know the OZ/Inch spec, but my
gantry (about 250lbs) can be driven by one of these things at 4inches/second
at a low gear ratio. If you don't care about speed, it's a good cheap
alternative. I feed mine at 50VDC at 2.5Amps and you can't stop the gantry
at 3:1 ratio, it will crush your hand. Re-wiring the motor is trivial and
you can get about two rev's per second from them or 120RPM. Not fast for a
stepper, but with their strength, you don't have to gear down as much.
Just do a web search for SLO-SYN AC SYNCRONOUS motor. They general sell
surplus for about $29.00 or less, weigh about 5lbs each or more, and under
the cover, you can just make about 10 cuts on a PC board, solder 4 wires to
the PC Board,and solder a few jumpers on the same board and voila, you have
a cheap strongman motor that I'll bet can turn just about any control
without gearing it at all if you don't need tight resolution. Let me know if
you want the wirng details. It takes me about 30 minutes per motor to rewire
them, and so far we've done 6 of them and are too happy with the results.

Art

----- Original Message -----
From: "Alan Marconett KM6VV" <KM6VV@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Monday, May 28, 2001 1:52 PM
Subject: Re: [CAD_CAM_EDM_DRO] which steppers to buy?


> Hi John,
>
> I understand what you are saying! I'd expect that you'd need something
> like 300-400 oz/in (from what I've heard for mill/drills, and 3 in 1's,
> but hay, If the motor mount fits, try it! I plan to try some old NEMA
> #34 S/S 300 oz/in motors on my new RF-31 mill, with 3:1 drives, even
> though their not really big enough! I will put on bigger steppers when
> I can afford them! For now, I'll even leave the Acme lead screws!
>
> Alan KM6VV
>
> marble here wrote:
> >
> > Ok Group every one is saying to use at least a 200oz
> > stepper .I called Smithy and asked then what they
> > would suggest stepper s for the 17X20 3 in 1 they sell
> > I was told that a 150 oz stepper and a 3:1 timing gear
> > now I am confused is this rating they say too small I
> > do have these stepper s now. I thought I should give
> > them a try just for the heck of it . Am I looking for
> > trouble using a small stepper I know that I can not
> > get any real speed out of them , but going slow I
> > think may be go till I learn more.
> >
> > John
>
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