[Gyvven]

I was at my local surplus store and I found a bunch of steppers for $5 each. They are Pacific Scientific M22NRXD-LSS-NS-08, and from everything I've been able to find out about them they are approximately a 240 oz motor. I wasn't able to find this exact motor but found several M22NRXD models.

Here's the info off the labe:
model: M22NRXD-LSS-NS-08
Po; 55 W (I'm not sure if this means watts or not)
VS (DC) 65
1.25 A Bipolar series
1.8 deg Step

The specs online for other M22NRXD motors report holding torque per winding as 1.62 to 1.79 Nm. What does per winding mean?

http://www.micromech.co.uk/dir_produ...powermax.shtml

Can anyone verify that I'm calculating this correctly? Will these be strong enough to power a JGRO or Joe's design? I'll run up and buy them if you say so.


Thanks,

Gyv

[jcoats]

http://en.wikipedia.org/wiki/Stepper_motor will give you an overview of stepper motors.

At 240 in/oz they are OK. Not to under powered, not really powerful though.

A good place to start! ... make sure any controller you get supports the type of motor (bi-polar I think you said, the other option is unipolar)

[Gyvven]

Jcoats,

Thanks for the Wiki.

I did some digging, called PacSci, and found out these were for a proprietary use and they couldn't give any other info. Probably an over-run that didn't get used, hence my find in the surplus store.

But I'm now confused because the specs on the PacSci website say they are 1.68Nm, period, whereas the link above says per winding. Looking at the motors at Hobby CNC they are getting a 40% increase going from unipolar to bipolar. Would that hold true for these? And then I need to find a way to get 65v to them. Any suggestions there?

[irving2008]

You can ignore the 65v specification. This is NOT the voltage to use but the maximum voltage that can be applied to a winding before breakdown. All it tells you is that you shouldn't use more than 65v on the driver. The important spec is the 1.25A per winding. The other detail gleaned from the label is they are wired bipolar series, so the phase coils are in series - higher resistance, higher inductance - which means these motors are going to struggle to give torque at high speeds - but for your application they should satisfy to get you started. I would look for a 36 or 48v driver to get the best out of them (Gecko G540 for example), you may find them underpowered to get reasonable rapids on 24v. The Gecko might be overkill now, but gives you scope to upgrade the motors later.

[automationtechinc]

You can ignore the 65v specification. This is NOT the voltage to use but the maximum voltage that can be applied to a winding before breakdown. All it tells you is that you shouldn't use more than 65v on the driver. The important spec is the 1.25A per winding. The other detail gleaned from the label is they are wired bipolar series, so the phase coils are in series - higher resistance, higher inductance - which means these motors are going to struggle to give torque at high speeds - but for your application they should satisfy to get you started. I would look for a 36 or 48v driver to get the best out of them (Gecko G540 for example), you may find them underpowered to get reasonable rapids on 24v. The Gecko might be overkill now, but gives you scope to upgrade the motors later.

check here to see the stepper motors
http://www.kelinginc.net/StepperMotor.html

[KTP]

Here are your motors:

http://www.pacsci.com/products/step_...xproducts.html

If they are the double stack M series, which by your part number they seem to be, then indeed they are 253 oz-in motors with rare earth magnets imbedded between the poles. A very nice motor for $50, a steal at $5.

I would think they would be of far higher quality than the made-in-china models everyone else sells.

[Gyvven]

Irving, thanks. I was wondering about the voltage and speed. But I have a question about the "Bipolar Series" statement on the label; since the motors have an 8 pin connector can't they be wired any way I choose? FYi - The RPMs are also listed on the label as 1500.

I currently have a decent 24v PSU and will be starting with that and probably a hobbycnc board since my budget is half a shoestring and it's WAF is considerably higher due to it's price.

I'll start off with a JGRO based on cost and my own stock of 3/4" MDF and black gas pipe lying around. I figure I'll end up spending $200-300 in the next couple weeks. I'm sure that price will rise, but I can hope. I'll start a new thread for my build soon.

[KTP]

Gyvven, here is the hookup diagram from the pacsci website:

http://www.pacsci.com/support/docume...llbulletin.pdf

That will show you how to wire them in unipolar, bipolar parallel and bipolar series.

[Gyvven]

A very nice motor for $50, a steal at $5.

And don't I know it!

And thanks, I had already found the hook up diagram. I was wondering if somehow the label was saying that the motor was hardwired into a bipolar series configuration.

I ran out yesterday and nabbed 3, they still have 4 more if anyone is interested (and is close to Minneapolis). I got them at Ax-Man in Crystal. They seem to be new-old-stock, and I haven't tested them yet.

If anyone is really interested I might be convinced to buy them and ship them, no added cost other than taxes and shipping.

[KTP]

No, they are not hardwired or prewired in any configuration. The label is just stating the specs for a common wiring configuration for those type motors.

[Mike Nash]

Unless you are on a shoestring budget, you ought to grab the other 4. If you've spent any time at all reading these forums you should realize there will be a second machine. $20+tax for four motors instead of $39 each is a no brainer. Besides, they're worth a bunch on ebay if you decide you can't use them.

If you really don't want them, I'll send you a check for the 4 for $10 each plus whatever for shipping. You can wait for it to clear the bank too. I don't need them, but I have a friend who's forever wanting to me CNC his stuff.

[vlmarshall]

Grab a fourth for yourself as a spare! You may need it one day, as a replacement, or for a dual-screw axis. While you're there, grab the others.

[irving2008]

Irving, thanks. I was wondering about the voltage and speed. But I have a question about the "Bipolar Series" statement on the label; since the motors have an 8 pin connector can't they be wired any way I choose? FYi - The RPMs are also listed on the label as 1500.

I currently have a decent 24v PSU and will be starting with that and probably a hobbycnc board since my budget is half a shoestring and it's WAF is considerably higher due to it's price.

I'll start off with a JGRO based on cost and my own stock of 3/4" MDF and black gas pipe lying around. I figure I'll end up spending $200-300 in the next couple weeks. I'm sure that price will rise, but I can hope. I'll start a new thread for my build soon.

As others have said, if you have all 8 wires then you can wire how you like, sometimes they are hard-wired. In which case go for bipolar parallel connection (2.5A/phase), you'll need a driver that can cope and a supply good for 5 - 6A for 3-axis. 24v will do in that config but I can guarantee you'll want to go higher soon but whether you can will depend on what driver you go for.

If budget is tight you could go for a Unipolar configuration as a unipolar drivers can be cheaper (1.77A/phase needed), but look for one with chopper or PWM current control. Don't go for one needing a voltage dropping resistor, its cheap but a false economy and you wont get anything like the performance you expect from the motor; most of your power input will be heating up the dropper resistors.

The 1500rpm on the label is indicative of the 'special' nature of the motor and may indicate maximum step rate in the environment it was designed for (1500rpm = 5000 steps/sec).

The attachment is the page from the PacSci catalog listing the specs for the M22NxxD series...

[ger21]

Before the influx of Chinese steppers a few years ago, I paid about $60 each for used M22 series steppers on Ebay. Mine are rated 2.3a series, though. I believe they are a well over $100 if purchased new.

[Gyvven]

Sorry, for not monitoring the thread for the last couple days. I've been busy ordering and building. I've also got a foundry build in the works. Hey, when you get laid off you might as well build stuff.

Irving thanks for the spec sheet from the catalog, the data I found didn't illustrate the differences in connections. That drop in torque is a little disappointing when going to the unipolar configuration. Oh, well.

I ordered the HobbyCNC EZ board and finished putting it together this morning. Yes I'm on a shoestring budget. (More like velcro, if anyone remembers those shoes. Cheap, easy and fast to get into.) I'll look for a bipolar driver later on, when I can afford it. I just hope the 168 oz-in is enough for a JGRO. It should be if I go with an acme screw instead of all-thread. I'm not planning on alot of ipm anyway, I just want something that works.

Mike, I'll PM you about those other motors. I'll run up and see if they're still there.

Thanks to all for the help and advice.

Gyv