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I have 3 CD drive stepper motors on a 9V 2A power supply, and they are being driven with EasyDrivers. I am using an Arduino with grbl to control the drivers. The current for the motors is at the lowest point possible (because the voltage at TP1 on the EasyDriver is at the lowest point possible), but the motors are still very hot (painful to touch) for some reason.

I have been testing out the motors with commands like X10 Y10 with an acceleration of 10 mm/s^2 to get the motors to move. However, the motors will still be very hot. Is this part of the problem?

But the strangest part is the the motors will move for way more distance than they should- they will just "roll" as if they are not torqued at all after they move the assigned 10 mm. But when they are stopped, there is definitely torque on the motor.

How do I fix this behavior? I can't change the voltage, so should I change the acceleration, or the current supplied to the motors, or something else?

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  • \$\begingroup\$ If you shut everything off and let it cool down do they work again? How hot is the driver chip getting? I believe they have thermal shutdown built in. It's possible you're overheating the driver. \$\endgroup\$ – jwygralak67 Nov 11 '13 at 19:46
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    \$\begingroup\$ You should probably be able to reduce the current either by changing the sense resistor, or else getting out of chopping mode entirely by lowering the power supply (if still in the working range) or adding power resistors in series with the coils. \$\endgroup\$ – Chris Stratton Nov 11 '13 at 19:58
  • \$\begingroup\$ @jwygralak67 Yup, when I turn it back on again everything still works. And I have a fan cooling the drivers... They are not very hot. \$\endgroup\$ – Blue Ice Nov 11 '13 at 20:17
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    \$\begingroup\$ @jwygralak67 EDIT: Never mind about the device turning off after 5 min. Turns out that I accidentally unplugged the power cable. :) \$\endgroup\$ – Blue Ice Nov 11 '13 at 20:24
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    \$\begingroup\$ Schematics ? Obviously there is a problem. And if you are here it's because you want some help to find your error. Because there is an error somewhere. If you say that the motor is correctly connected, let us doubt about that. In fact, let us doubt about everything! That's the way we could find the error, ultimately. Thus we have to know what you intended to do (the schematics) and then we could, at least, answer if the problem is at the intention (design) or implementation (build stuff is not what the schematics says). Thus, please provide a schematics. \$\endgroup\$ – Blup1980 Nov 12 '13 at 12:22

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