Not working Extruder Stepper [SOLVED]

Hey Folks,

tonight a strange problem occured. The reading of the noozle went over 300° while i was away. So the electronics stopped heating, but the reading sticked at over 300 degree. The noozle totally cooled down, but the print went on.

So the stepper tried to extrude the filament through the cold noozle, which was obvioulsy not possible. When i came to the print in the morning, it was printing in the air. I stopped the pint and tried now to reprint, noticing, the extruder motor wont work.

It just kinda vibrates, but doesnt move the crank. Any idea on how to fix that? Even tried it on an external PSU with 1,2A... Just vibrating...
Do i need a new motor? If yes, is it covered by warranty?

Thanks mates,
nice printing,
Andreas

Edited 1 time(s). Last edit at 02/08/2014 12:52PM by djar.

I suggest you first remove the stepper from the extruder unit and check that the shaft rotates freely. Others here have reported that steppers can very occasionally get contaminated with metal particles, which causes them to lock until they are cleaned out.

If it rotates freely, but still won't rotate when you send extruder commands, you then need to determine whether the problem is in the stepper motor, the wiring loom, or the Duet board. For example, unplug the extruder loom from the stepper and connect it to one of the other steppers, then see if you can make that stepper rotate if you give it extruder commands.

It should not be possible to burn out a stepper or the Duet board by locking the shaft. So if a component has failed, then IMO it should be covered under warranty.

Edited 3 time(s). Last edit at 02/08/2014 10:34AM 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].

Thanks for your suggestions. After playing around a while, trying the stepper on other connectors, then powering off the board, let it be for a while and trying it again, it works again. How can that be? Overheating in the stepper driver?

Quote
djar
Thanks for your suggestions. After playing around a while, trying the stepper on other connectors, then powering off the board, let it be for a while and trying it again, it works again. How can that be? Overheating in the stepper driver?

More likely a dodgy connection, either in the wiring loom, on the Duet board, or just possibly in the stepper motor. If any one of the 4 connections doesn't make good contact, the motor will vibrate instead of step.

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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].