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Overheating Stepper motors

Posted by Architect 
Overheating Stepper motors
January 12, 2011 10:44AM
any ideas are appreciated.
I have some eBay NEMA 17 stepper motors which have resistance of 4.2 ohms across the coils. I am driving them with the pololu A4983 drivers with a power supply of 12V. they are functioning and work fine when tuned using the pot on the driver but, after a short time the motors become too hot to touch and i am afraid they may melt the mounts on my Mendel or damage the motors themselves. the driver board does not seem to get very warm no matter what I set the pots too.

What are my options? I am planing on using the RAMPS circuit board to house the Drivers, can I put in some form of current divider to lower the output to the motors or should I lower the input voltage to say 8 or 9v?
Thanks again.
Re: Overheating Stepper motors
January 12, 2011 11:55AM
Stepper motors will get too hot for plastic brackets if you run them at the maximum rating, which usually states 80C rise.

Just reduce the current with the pot by about 30%, that will give you 70% of the torque but half the temperature rise. That way they run at about 60C rather than 100C. If you have PLA brackets you need to keep it below 50C.

Re: Overheating Stepper motors
January 12, 2011 06:03PM
thanks for the info 50 C seems incredibly hot but thats around where they are, I'll check the temps while they are running.
again thanks for the info.
Re: Overheating Stepper motors
January 13, 2011 04:55AM
... you can fix some heat sinks to the motors and blow air over them, so they'll stay cooler ...

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Re: Overheating Stepper motors
November 18, 2011 01:39PM
I have the same problem and I HAVE melted my stepper mounts (PLA)

still trying to adjust the power to find a happy meduim
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