Re: Yet another NEMA 42 roadblock

Jeff,

Good to know your persistance has resulted in this reward. Good luck

Ballendo

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Jeff Goldberg" <jeff@w...>
wrote:

> 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@j...> [mailto:davemucha@j...]
> 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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