Printer sits with hot end on print for ~4 1/2 minutes(!!) before End

  • So, this is odd and scary. I've just completed my 6th or 7th print with the Duet, using the same slicer (Cura) and same start/end gcode.

    I just wrapped up a 9h print and I was monitoring the printer because it was getting close to done. I watched the print head move to a corner of the print and just stop. It sat there for a few seconds while I fumbled with the bed and pulled it out of the way. It had started melting a hole into the print, but thankfully it doesn't impact it much.

    I took a screen shot of the web interface next.

    I highlighted a few things.

    • The Duet was reporting 95.6% completion.

    • Both heaters had beed turned off.

    • The total layers was reporting 21. It was actually 154, with a last, 155th layer for ironing, which had been completed. (Cura counts ironing as a layer apparently)

    • The filament usage was WAY off. Or it was accurate and the expected usage was way off.

    About 4 minutes after I took the screen shot, the printer homed X and Y, and raised the Z by 5mm as the end G-Code tells it to.

    This happened once before, though I didn't see it happened and was scratching my head about it. I printed a small calibration cube and came back to see it stuck to the hot end, off the print bed by about 5mm with the X and Y homed.

    My gut is telling me ironing has something to do with this, but all of my prints have been ironed on the top layer for a week or so now.

    Here's my end GCode from Cura, I think it's clear this was hit because the heaters were off. Not sure where it went wrong.

    M104 S0 ;extruder heater off
    M140 S0 ;heated bed heater off (if you have it)
    G91 ;relative positioning
    G1 E-1 F300  ;retract the filament a bit before lifting the nozzle, to release some of the pressure
    G1 Z+5 E-5 X-20 Y-20 F9000 ;move Z up a bit and retract filament even more
    G28 X0 Y0 ;move X/Y to min endstops, so the head is out of the way
    M84 ;steppers off
    G90 ;absolute positioning

  • administrators

    You should have M83 as well as G91 in that end gcode, otherwise you are relying on Cura having just sent G92 E0 shortly before that end GCode so that the G1 E-1 is relative to the current position. Other than that, I don't see anything that would cause a problem.

  • Hi dc42, I expect this will happen again, anything I can do to capture more information on the problem? I should have run an m122, now that I think about it.

  • administrators

    Is it a Duet WiFi or Duet Ethernet?

  • @dc42:

    Is it a Duet WiFi or Duet Ethernet?

    Sorry David, I didn't see you had replied. It is a Duet Wifi. I'm running 1.20 (2017-12-23).

    I can also confirm it is not the new ironing setting that's causing any issues. This has happened on all three of my prints since I posted, two of which don't have ironing on. The machine is basically frozen while this occurs, I have to do an emergency stop (the normal M0 stop does nothing) and wait for it to boot back up before moving my print head away from my print.

    It's definitely hitting the end code - I see the extruder retract but after that, it hangs. The next line in my end code is

    G1 Z+5 E-5 X-20 Y-20 F9000 ;move Z up a bit and retract filament even more

    Any ideas?

    Thanks again.

  • administrators

    Please add the M83 command that I suggested earlier to your end GCode, also upgrade your firmware to 1.21RC3 (read the upgrade notes first) and see whether the problem is resolved.

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