Which stepper motors should I use?

[Robotics Guy]

I'm trying to build a *very* small CNC machine to drill homemade PCBs. I've decided to go the cheap route, using threaded rod from the local hardware store, which hopefully will work OK for my purposes. The frame shouldn't be too hard to build, but the thing that I'm most concerned about is which stepper motors to use. I don't think they need to be very powerful, since my machine is so small and only is going to be used for drilling.

The website I've been looking at for stepper motors is alltronics.com. I've never purchased from them, but they have lots of different motors reasonably priced. These are the ones in my price range:

http://www.alltronics.com/cgi-bin/it...-stepper-motor
http://www.alltronics.com/cgi-bin/it...-stepper-motor
http://www.alltronics.com/cgi-bin/it...-stepper-motor
http://www.alltronics.com/cgi-bin/it...-stepper-motor
http://www.alltronics.com/cgi-bin/it...-stepper-motor

Does anyone have some advice for me on what motor to use? Is there a better website to order from?

I really appreciate the help, thanks

[pminmo]

Here is another alternative: http://www.mpja.com/prodinfo.asp?number=17748+MS

You can see this motor run in this video of mine: http://pminmo.com/which-stepper-motor

There are two different motors illistrated in the video, the 2A motor (faster one of the two) in the video is the same motor at mpja, just doesn't have the second shaft.

[Robotics Guy]

Thanks for the recommendation! I think I'll go ahead and buy three of the motors you linked to. In addition to knowing that they work, they are cheaper then the ones I was looking at!

Would you happen to know the correct way to wire them?

Did the stepper motor pull a full 2A when you ran it? The reason I ask is because I have these motor drivers on hand.

[pminmo]

The motors were set at 2A.

[Robotics Guy]

Hi pminmo,

What voltage do you think is best to run the PK266-02A at?

[pminmo]

For the money up to 40V, you can run it higer but cost verses benifit curve changes. Little performance improvement verses cost of higher components...(driver and power supply). Even at 27V it's a zippy little motor.

[Robotics Guy]

pminmo, thanks for all of your help.

The stepper motor controller that I'm building says (in one of the IC's datasheets)

drives two phase bipolar permanent magnet motors, four phase unipolar
permanent magnet motors and four phase variable reluctance motors

I'm wondering what you think is better, unipolar or bipolar?

[pminmo]

It's not a simple answer unfortunately. If you have a six wire motor and you want rapids, there is little difference between half coil bipolar and unipolar at the same driver voltage levels. If you can run at much higher voltage levels, then full coil bipolar will give you more power. It depends on the coil voltage ratio of the motor supply.

[Robotics Guy]

Is the 36V 10A power supply enough to run full coil, do you think? If not, to run it half coil do I just use the center tap with one of the other wires?

[Robotics Guy]

So with my 36V power supply should I run it half coil or full coil?

In either case, do I wire it as in this picture?

http://www.probotix.com/cnc_images/unipolar_ill_02.jpg

[Kelinginc]

I'm trying to build a *very* small CNC machine to drill homemade PCBs. I've decided to go the cheap route, using threaded rod from the local hardware store, which hopefully will work OK for my purposes. The frame shouldn't be too hard to build, but the thing that I'm most concerned about is which stepper motors to use. I don't think they need to be very powerful, since my machine is so small and only is going to be used for drilling.

The website I've been looking at for stepper motors is alltronics.com. I've never purchased from them, but they have lots of different motors reasonably priced. These are the ones in my price range:

http://www.alltronics.com/cgi-bin/it...-stepper-motor
http://www.alltronics.com/cgi-bin/it...-stepper-motor
http://www.alltronics.com/cgi-bin/it...-stepper-motor
http://www.alltronics.com/cgi-bin/it...-stepper-motor
http://www.alltronics.com/cgi-bin/it...-stepper-motor

Does anyone have some advice for me on what motor to use? Is there a better website to order from?

I really appreciate the help, thanks

This motor will be ok
NEMA 23 BIPOLAR STEPPER MOTOR 185 oz-in
http://www.kelinginc.net/NEMA23Motor.html

[pminmo]

Depends on your screw pitch.