Potentially toasted stepper? Y-axis loses steps in one direction

Hi Guys,

I've been lurking the forum for a long time and just recently finished final assembly on a semi-customized MendelMax 2. Right now i'm in the process of calibrating everything and I'm concerned I left calibrating the stepper currents until last...

If the printer has been on for a little while (10 min?) the Y axis will lose steps in the - direction on non-print moves. The very first calibration cube print didn't see this problem, but revisiting the same g-code after spending time doing bed leveling and making sure everything is square results in a print where the first few layers are square, then they start drifting off in the Y direction. The Y stepper is very hot to the touch, hot enough I can't keep my fingers on it. If I try to dial back the current at the stepper driver, it stops moving in the Y- direction (though Y+ will still work).

I've tried varying the tension on the belt which may have been over tight to begin with. I've tried playing with the current as noted above. I haven't done much on changing up the acceleration/max speed, though i'd like to be able to keep that as high as possible.

Since this only seems to be a problem in one direction, i'm worried that I blew the stepper. Thoughts? Debug steps? Is it possible to re-built steppers?

Thanks!

If the stepper motor is moving consistently at all, it isn't blown, although it's possible that it is binding when hot. Check that the Y axis moves freely in both directions when the printer is not powered, and try replacing the stepper driver module that drives the Y motor.

Edited 2 time(s). Last edit at 05/29/2015 06:32PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I'm concerned about the binding at hot. Will try swapping out motors with one of the Z axis motors (since they don't seen to need as high torque nor get as hot) and swap stepper drivers to see if either helps.

Thanks for the input!