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Nema 17 motor for HobbyCNC?

Posted: Tue Mar 19, 2013 3:59 pm
by JoyMonkey
I have some hefty Nema 23 motors (305oz/in) that came with a HobbyCNC kit that I am going to use for the X and double Y axis. I picked up a Nema 17 from Inventables to run the Z axis. I figured the motor from Inventables would use less amps, be lighter, and be plenty powerful enough for what the Z axis needs.
Unfortunately, I didn't realize that the HobbyCNC driver boards can't run 4-wire bipolar stepper motors, which are exactly what the motors from Inventables seem to be.

Can anyone suggest a motor similar to the Inventables Nema 17 motor, but not bipolar?

Re: Nema 17 motor for HobbyCNC?

Posted: Tue Mar 19, 2013 6:56 pm
by Improbable Construct
I would check eBay.
Look for a NEMA 17 motor in the high 60 oz/in range.
70 oz/in is the most torque I have seen.
If you search by Located in USA only you Wong have to wait for shopping from china.
Do you need a 6 or 8 wire motor?

Re: Nema 17 motor for HobbyCNC?

Posted: Tue Mar 19, 2013 7:06 pm
by JoyMonkey
6 or 8 wire motors will work with the HobbyCNC Pro board, they just need to be unipolar. I'm having a look on eBay now. How does this one look...
http://www.ebay.com/itm/200907115080 (Spec sheet attached)

Re: Nema 17 motor for HobbyCNC?

Posted: Tue Mar 19, 2013 7:32 pm
by Improbable Construct
I would say it is a bit undersized at only 42 oz/in.
I think you want to look for something with more holding torque.
If you want to use a NEMA 23 motor for the Z axis
I do sell a kit...

Re: Nema 17 motor for HobbyCNC?

Posted: Tue Mar 19, 2013 7:54 pm
by JoyMonkey
Thanks.
Looking around, I don't see any unipolar Nema 17 motors with torque over 42 oz/in.
I do have a Nema 23 305oz motor to spare (I have 4 of those total), but I'm afraid that all 4 running together will be pulling too much current. Plus it's heavy as hell.
I guess I can try it out and see if any fuses blow, or find a smaller Nema 23.

Re: Nema 17 motor for HobbyCNC?

Posted: Tue Mar 19, 2013 8:37 pm
by pagercam
I'm no expert but from my looking around it generally seems that NEMA17 steppers top out at something like 68 oz-in and NEMA23 seem to start at 100 oz-in and go to something over 300 oz-in. Bipolar models seem to be about 30% stronger than unipolar models so something like 48 oz-in maybe as high as you can find in unipolar NEMA17s. There are probably some higher power ones but those will be a harder to find and much heavier (longer than standard). So it might be easier to find a smaller NEMA23.

Re: Nema 17 motor for HobbyCNC?

Posted: Fri Nov 15, 2013 6:51 pm
by samc99us
Just wanted to update folks if you're looking for a unipolar (6 wire) NEMA 17 motor.

This is the beefiest motor I could find for a reasonable price: http://www.aliexpress.com/snapshot/294063555.html

If you're in a rush (I'm not and can wait for shipping from China), then Pololu might be able to help you out: http://www.pololu.com/product/1200

Re: Nema 17 motor for HobbyCNC?

Posted: Fri Nov 15, 2013 11:02 pm
by cvoinescu
The Pololu motor has unimpressive torque, especially for a motor 48 mm long. Not sure whether that's because they measure it differently from the one from AliExpress, or it's a genuine difference.

Re: Nema 17 motor for HobbyCNC?

Posted: Tue Nov 19, 2013 4:55 am
by jland
I ordered some of these 92 oz-in Nema 17s from Stepper-Online directly here. I made the order of stepper motors and power supplies on Friday and got them today (Monday) shipped with DHL. Everything was very well packed. Unfortunately, it won't be until next year when my Shapeoko 2 kit arrives that I'll be able to test them!

Re: Nema 17 motor for HobbyCNC?

Posted: Tue Nov 19, 2013 5:52 pm
by Tom Smith
jland wrote:I ordered some of these 92 oz-in Nema 17s from Stepper-Online directly here. I made the order of stepper motors and power supplies on Friday and got them today (Monday) shipped with DHL. Everything was very well packed. Unfortunately, it won't be until next year when my Shapeoko 2 kit arrives that I'll be able to test them!

I HIGHLY recommend that you start out by choosing, and obtaining, an Arduino and the control board you plan on using, and a power supply so that you can get used to using the software->control chain even before the mechanicals are assembled. I assume you are sourcing the electronics yourself, given how you are stepper shopping :)

Pre-build activities include:
  1. Flashing Arduino with GRBL
  2. Connecting Arduino with Control board (gShield, tiny G, etc)
  3. Hooking up power to control board
  4. Connecting motors to control
  5. Manually jogging motors from your pc, using raw GCode, or a control program such as Universal GCode Sender
  6. Drawing a shape, converting to GCode, and sending GCode to Arduino using the software above
All this stuff gets you familiar with the process so that once you put the machine together, you know that you have a handle on the control electronics, and therefore, hopefully, are able to debug issues with a good basis on the control side. Additionally, it is all documented on the wiki, so you don't need to do too much research to figure it all out :) (most current is here)

Tom