RE: [CAD_CAM_EDM_DRO] Re: Yet another NEMA 42 roadblock

First I want to thank everyone for their assistance.

Perseverance apparently pays off occasionally. I got a hold of a Superior
Electric engineer who used to work for Sigma Instruments before Superior
bought them more than twenty years ago (reason there was no mention of Sigma
on the web).

For reference for anyone else with this problem in the future:

The stepper is apparently Sigma part number: 21-4288-D200-F03
He said it was generally run at over 100 volts so running it at 65 volts DC
is apparently fine
The rated current is 12.5 amps (he recommended for milling to run it at no
more than 6.25 amps in series as he said it is a slow speed-high torque
application) He recommended against 1/2 winding as not beneficial unless
drivers were too small

The motor is rated at 1800 oz/in holding torque and 1500 oz/in running, 50
steps/sec, 200 steps/revolution

Now the best part:

In parallel:

Phase A: terminal 6 is jumpered to terminal 3, terminal 1 is jumpered to
terminal 5
Phase B: terminal 4 is jumpered to terminal 8, terminal 7 is jumpered to
terminal 2

In series:

Phase A: terminal 1, 6 is jumpered to 5, Phase A': terminal 3
Phase B: terminal 7, 4 is jumpered to 2, Phase B': terminal 8

Based on his advice, I think I'm going to raise the power supply voltage,
cover my eyes, hold my ears and throw the switch.

I'm always open to last minute advice before I melt this thing down!

Regards,
Jeff



-----Original Message-----
From: turbulatordude <davemucha@...> [mailto:davemucha@...]
Sent: Thursday, February 20, 2003 11:12 AM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Re: Yet another NEMA 42 roadblock


<snip>

>
> Jeff,
>
> You won't likely hurt your motor if you connect the coils
> incorrectly. I think your motor does not match the one you have
> documents of. So go ahead and connect it in various ways. It will
> just sit and hum, or buzz if you get it wrong. Keep trying, that's
> one of the prices of "surplus" motors<G>
>
> Hope this helps,
>
> Ballendo
>
> P.S. I think Mariss has said that you CAN hurt a DRIVE, if you hook
> up an 8 wire motor incorrectly!

<snip>


2 things, first, I think these are existing froma 120volt or higher
system so if they were run at 100 volts and 8 amps, or 800 watts,
running them at 30 volts and 4 amps or 120 watts will show they are
working, but not do heavy duty work.

Second point is that you are correct that completely miswired ie:coil
A into coil B on the drive will cause damage. That is why I said to
use single coils and not mess with guessing how to use the 8 wire in
series or parallel. besided probably half of us use only 2 coils to
begin with and the 3% gain is not worth the worry to a newbie.

Dave





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