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Bad Nema 17 stepper motor?

Posted by Sambone 
Bad Nema 17 stepper motor?
December 25, 2020 12:37AM
During a print my x axis most frequently gives out. I just did an ohm check. Any documentation shows my coils should be about 2-3 ohms (4V/1.5A). However I get a standard 30 ohms amongst all motors, with my failing motor having one about 50, and my larger y axis motor is about 8 for each.

As for prints failing, anything from scrambled garbage on my lcd display, motor skipping steps or shifting and working partially, or giving out completely. This causes a trough to be printed running on the y axis.

Does this indicate a fried motor, or do I potentially have fried drivers? I've shuffled them around before and thought I was able to isolate a fried driver, but I still occasionally got issues.

Running on a Folger Tech Prusa i3 acrylic frame now with dual extruders.
Re: Bad Nema 17 stepper motor?
January 04, 2021 10:43PM
Well, I solved my issue. I now have a fan on my stepper drivers. One heatsink fell off long ago so I made the attempt to go the extra mile and use thermal paste. I suppose I never got them mounted correctly. Just bought PETG for the first time and enjoying my functional printer again.
Re: Bad Nema 17 stepper motor?
January 05, 2021 05:11AM
Thanks for sharing the solution

Re: Bad Nema 17 stepper motor?
January 05, 2021 11:27AM
Stepper motors almost never fail. All they are is fixed coils of wire and magnets on a spinning rotor. After a LOT of use, the bearings may fail depending on how the motor is loaded, but it's really hard to burn up the coils. If you do burn up the coils, you will be able to smell it. No smell, no burned coils.

I had an industrial surplus stepper fail after several years in a 3D printer (plus God only knows how much use in the machine it was pulled from). The bearing races started flaking apart and bits of metal got lodged between the rotor and stator pole pieces. Operating became rough, but didn't stop the motor from turning. The motor was as good as new when the bearings were replaced and the rotor and stator cleaned off.

Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
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