[Mini Miller]

Hey guys, I have done so much research that my head is spinning. I have purchased a set of Superior Electric Slo-Syn series M092-FD08 steppers for my Grizzly mini-mill cnc project. The motors are rated at 3 volts, 4 amps and I will be using a 48 volt, 10 amp power supply.

I am looking for a low cost stepper drive that can take 50 volts or more and handle 4 amps per phase. I have looked at most of the drive makers that we know of and a lot of them only handle 2.5 or 3 amps, or the voltage is not high enough. Is my only choice to go with Gecko 201 drives?

From what I have read here, the recommendation is to go with a half-winding wiring scheme for fast stepping and higher power output. Is it not a good idea to go with a full-winding scheme and get a lower power drive? How about some of the unipolar drives with less features? They seem to have the right current handling capacity.

Thanks for any help that you can offer.
Mini-Miller

[vladdy]

check out ebay [or other auctions] for the actual matching drivers, Superior Electric... I picked up a couple of PDM500'a and a PDT155 a while ago, less than $40 each as far as I remember..
Everything is there, hook up 110v, the motor, and the step direction lines, and go..
the PDM500 shows that those motors are driven at 3a when using a Superior controller...[bipolar]

[swarfmacdaddy]

Mini, believe me, geckos are not your only choice, but they are the only choice a sane person would make. Their customer service alone is well worth the price. They never grew tired of my stupid questions. They were always cheerful.and i know they must have answered the same questions a thousand times before from others who thought they were the only person that bought geckos. point of story: I wired one wrong and smoked it, They fixed it for free, I dropped one on a concrete floor, fixed for free. Dont even count on that kind of service from anyone else!! NO i dont work for them. I am just relating my experience with them. I bought controller software from a vendor(who shall remain nameless) and got nothing but rude, insulting responses to my questions.After dropping $200 on their crap. Really, stick with the standard. You wont regret it.

[swarfmacdaddy]

Mini, sorry i didnt read close enough. Why do you want to run @ 10 amps? I would still opt for Geckos and run em open @ the 8 amp limit.

[ViperTX]

Mini Miller,

3 volt coils and you want to run them at 48 volts at their max. current? Why, just wanna cook them? I didn't see any max. volt spec. on the data sheet...but there should be a max. power spec. I would be looking for a much lower supply voltage and a current rating of closer to 20 to 25 amps.

[Mini Miller]

Hey Viper and Randy, as I understand, you want a power supply that is 20 - 25 times the voltage of your motor which would be upwards of 60 volts. I happen to have found a very nice unregulated, toroidial power supply that is rated at 42 volts, 10 amps. Sounds perfect to me. Am I missing something?

For the current, you need to figure out how you are going to wire a motor, and add up all 3 of them. If I wire these in parallel (half-winding) mode, i'll be drawing all 4 amps that the motors are rated for. Take 67% of that number, add up all 3 motors, and I get about 8 amps. If I am figuring something wrong, please let me know.

As I am thinking about drives, I feel like I have to make a choice here.
1. wire the motors in series (full-winding) which uses half the rated current (2 amps), and go with a less expensive drive. This is not the most efficient way to run a stepper motor.

2. wire the motors in parallel (half-winding) which uses all 4 amps, and buy Gecko's. This is very efficient and gets more power for as given voltage.

I can't seem to find any other drives that are rated above 48 volts, 3 amps, and do bipolar and unipolar. I am dying to purchase something and get on with my project. Any help is appreciated.

Thanks guys,
Mini-Miller

[ViperTX]

Yes, you're probably underrated for current unless you're using a supply for each stepper. The key is that you must limit the current to the stepper to the maximum rated current or you'll have a toaster.

[ger21]

Hey Viper and Randy, as I understand, you want a power supply that is 20 - 25 times the voltage of your motor which would be upwards of 60 volts. I happen to have found a very nice unregulated, toroidial power supply that is rated at 42 volts, 10 amps. Sounds perfect to me. Am I missing something?

For the current, you need to figure out how you are going to wire a motor, and add up all 3 of them. If I wire these in parallel (half-winding) mode, i'll be drawing all 4 amps that the motors are rated for. Take 67% of that number, add up all 3 motors, and I get about 8 amps. If I am figuring something wrong, please let me know.

The 20-25x "rule" is something mentioned in the Gecko white papers, I believe. There has been some discussion of it's validity on some other groups. The higher the voltage, the higher the top speed you can attain. Also, the hotter your motors will get. Ideally, you want to use the lowest voltage to get the speed that you need. This will keep your motors the coolest. It won't hurt anything to run them @ 42V and see how they are working. Monitor the temp of the motors, make sure they stay under 100° C. I'd guess they will. If they get hotter , use less Voltage.

The 8a figure is correct for Gecko drives. Other drives may need more. It looks like you have a perfect power supply for those motors.

[BigDaddyG]

Mini,
Well I have to agree with Gerry! I have the same motors, run them on a 48vdc, 6 amp supply thru Stepperworld.com FET-3 boards. They are rated at 80vdc, and can handle up to 15 amp as supplied and can go higher with mosfits. They are priced at about 130.00 for a 3 axis board and they do sell a 4 axis (FET-4) as well. I just ordered some from them not too long ago and am very pleased.

Good Luck man and let me know how you make out,
Glen

[Mini Miller]

Yo BigDaddy! (I always wanted to say that).
That's the first good news I have heard all day. I have been all over the Stepperworld website and they give no specifications for their product other than the 15 amp current. So you are running M092's at 48 volts with a FET3? Are you happy with the features, performance, etc from that product? Maybe we can trade email offline so I can get some more details.

Thanks alot,
Min

[BigDaddyG]

Min,
Yepper! In fact I just got in touch with them and asked them to forward me the spec's on the boards so I could pass it along to you. Yes, I have some M092's on a Enco Conversion. I am very happy with the product and have been for some time. In fact, I expect to have 3 FET-3 boards waiting at my door when I get home tonight. I just ordered 3 for some conversions I am building and they are due in today. I will not go on too long now, as soon as I get the spec sheet I will get it to you. Contact me and send me your email address and I will be happy to lend any assistance I can. Where are you located, I am in the Sunny Tampa Fla area. Just send me a private contact.
Regards,
Glen

[ger21]

Since your'e using them on the mill the Stepperworld boards might work OK for you. Most of the guys that have used them on wood routers find them too slow. A gecko will give better performance, but if the FET works for you, go ahead and use it.

Glen, don't you need some big resistors on there to run at that voltage, though. Don't they generate a lot of heat?

[ccm]

Glen, I've got the FET3 as well and would be curious as to what you're using for Transistors as well. My motors are spec'd @ 1.7V 4.7A per phase.... and I'm running them @ 12V, using a transistor to limit the current down to 9.2amps or so.... but I've been unlucky trying to find 100 - 150Watt Power resistors online...I've got an Active Electronics store nearby, but the phone # doesn't work anymore ( did they get bought out and move to Canada ? ).
By my math.... I need @12vdc a 1.1ohm, 96 watt pwr resistor at least, right now I'm getting away with heatsink'd 1 ohm 25 watt units, BIG HEATSINKS!
And they're hot within minutes......
I'd be curious what you have figured out what works best.
I just got an email back from Russ over at S.W. and he says in his email that it's a good idea on the FET3 not to exceed 5amps per phase on each axis so even though they'll probably deal with 15amps / axis... he advises to keep it around 10amps or so total / axis.

- Art

[BigDaddyG]

Art,
Allied Electronic, 100w + heat sink mountable and about $20 - $30 each. Many different types to pick from. I have some projects underway and will be trying some different types and would be happy to pass my findings along in a few weeks. I am actually trying to find a specific type and stick with them. As it is now, I have been using what ever I could get my hands on, kept no documentation etc.......

I will be happy to pass on what I learn in the next few weeks if you can wait that long. But in the mean time I think you can find what your looking for at Allied, if you find something that works let me know.

Regards,
Glen

[ccm]

Thanks for the info Glen, looking forward to your findings.

-Arthur

[BigDaddyG]

Art,
I am looking mainly at the Caddock 100w Power Film (have some on order) at about $8 -10 a piece (cat page # 1160) and the FPA 100 Film Power Resistors (cat page 1158) at about 28.00 a piece. I think these are the ticket but want to make sure. Again, I will be happy to let you know. Contact me and remind me, I tend to be forgetfull!
Regards,
Glen

[ViperTX]

Glen, I've got the FET3 as well and would be curious as to what you're using for Transistors as well. My motors are spec'd @ 1.7V 4.7A per phase.... and I'm running them @ 12V, using a transistor to limit the current down to 9.2amps or so.... but I've been unlucky trying to find 100 - 150Watt Power resistors online...I've got an Active Electronics store nearby, but the phone # doesn't work anymore ( did they get bought out and move to Canada ? ).
By my math.... I need @12vdc a 1.1ohm, 96 watt pwr resistor at least, right now I'm getting away with heatsink'd 1 ohm 25 watt units, BIG HEATSINKS!
And they're hot within minutes......
I'd be curious what you have figured out what works best.
I just got an email back from Russ over at S.W. and he says in his email that it's a good idea on the FET3 not to exceed 5amps per phase on each axis so even though they'll probably deal with 15amps / axis... he advises to keep it around 10amps or so total / axis.

- Art

Look at having a power resistor per phase and you should be able to get by with a 50 watt 2 to 2.5 ohm resistor.

[BigDaddyG]

ViperTX,
Thanks, I thought I might be looking at the wrong ones, I am at work and my info is at home. Do you have any experience with any that you have used or liked?
Regards,
Glen

[fair451]

Mini Miller
Possibly this drive could be in the range of what you are looking for.
http://www.centent.com/cn0142.htm
I do have some of these available.

[ViperTX]

ViperTX,
Thanks, I thought I might be looking at the wrong ones, I am at work and my info is at home. Do you have any experience with any that you have used or liked?
Regards,
Glen

Glen,
You're asking about power resistors....I use whatever is available.