Extruder motor - possible board problem?
December 31, 2013 08:23AM
Hello everyone,
I've got to the commissioning stage of my Ormerod and appear to have a problem with the extruder motor circuit:

Problem:
Extruder motor judders rather than rotates

Troubleshooting already completed:
Ruled out motor: - disassembled extruder assembly and plugged E-motor into the Y axis loom. Operated Y axis through Pronterface - E-motor rotated perfectly
Ruled out wiring loom:- replaced z axis wiring loom with extruder loom. Operated Z axis through Pronterface - z-axis works perfectly
Pinpointing extruder connection on Duet board: plugged y-axis motor and loom into extruder socket of Duet board and operated extruder through Pronterface - Juttering y-axis.

I have the extruder loom plugged into the Duet board as described in the wiring section, with 3 empty pins to the left and 1 empty pin to the right of the connector. The red wire is to the left of all 4.

All other hardware plugged into the board is working correctly (having replaced the microSD card)

Please let me know if it's possible to plug the extruder in anywhere else on the board, or what other troubleshooting options are possible.
Re: Extruder motor - possible board problem?
December 31, 2013 09:23AM
As with the x-axis slider the 3mm washers can jam up the 9mm bearings in the extruder. I recommend dismantling the extruder and turning down the diameter of the washers to about 6mm. You can use an electric drill with 3mm screw and nut to hold the washers. Then a file to remove the excess. Do 3 washers to have one for the x slide.

Rory
Re: Extruder motor - possible board problem?
December 31, 2013 10:35AM
Thanks Rory,
Originally thinking the motor or cogs could be fouling on something, I disassembled the extruder assembly and simply have the motor without cogs or assembly plugged into the board (at which point it still stutters). As described above, I connected this motor into different ports at which point it worked, to prove the motor is not at fault.
I think either the software, firmware or board are at fault, as the motor and looms are shown to be OK. Does anyone know a direct G code I could use to try and turn the extruder motor?
Thanks,

#397
Re: Extruder motor - possible board problem?
December 31, 2013 10:37AM
I would check on the underside of the board that all 4 of the header pins that the extruder motor connects to have been soldered. It might also be worth examining the rightmost of the four A4982 chips on the top side, to see if there are any solder bridges between pins.

Edited 1 time(s). Last edit at 12/31/2013 10:37AM by dc42.



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].
Re: Extruder motor - possible board problem?
December 31, 2013 11:49AM
The 4 pins look well soldered and there's nothing obviously wrong with the soldering of the chip (my eyes aren't brilliant)... The top right pin (when holding it so the writing on the chip is the right way up) of the chip doesn't look spot on, but no more inconsistent than some of the others on the board.
LED D11, seemingly connected to that part of the circuit is constantly out (which I assume to be correct)
Can someone confirm whether pins 25-28 on motor/extruder loom are the same as the normal extruder pins - i.e. could I buy a 2x2 connector, remake the loom and try operating the extruder from there?
Thanks again,
Re: Extruder motor - possible board problem?
December 31, 2013 12:07PM
The LEDs next to A4982s are connected to the endstop switches. Only the y-axis of the Ormerod has an endstop switch, so only the Y-led comes on (it goes off when the endstop switch is activated).

You can find the schematic of the Duet board here.

Edited 1 time(s). Last edit at 12/31/2013 12:08PM by dc42.



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].
Re: Extruder motor - possible board problem?
December 31, 2013 01:19PM
Got to say that I would probably send the board back at this point. Its seems you have narrowed it down to "something" on the board.

Annoying I know but ...

regards
Andy


Ormerod #318
www.zoomworks.org - Free and Open Source Stuff smiling smiley
Re: Extruder motor - possible board problem?
January 01, 2014 05:52AM
Thanks - yep, I think I'll be doing that tomorrow when the German postoffice opens. Thanks for posting the circuit diagram - I disassembled the board end of the extruder loom and plugged it into the parallel pins of the 'motor loom' (pins 25 - 28). The result is that it stutters just as before - so I believe I have now narrowed it down to the extruder stepper driver section of the board, which I feel it is beyond my skill to attempt to troubleshoot and repair.
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