Really odd problem mid-print stops and fast retracts



  • Here's a new issue I haven't seen here, or with other firmware before.

    Midway through a long print, sliced with Kisslicer (Pro) - the print halts and the extruder starts spinning very fast retracting the filament for 10 min and then ends the print. This has happened twice at the same layer (layer:57) in the code.

    Just as a test, to see if the problem was the file, I edited the gcode, removed the layers up to 57 and restarted the print from that point and new weird behavior happens.
    The printer starts by spurting out a lot of filament and then clogs the hot-end.

    Understand, I've used this method many times with my rambo/repeier to fix prints that stopped in the middle, and this behavior has never happened. With the other firmware, the printer just starts printing at the height/XY positions and correct amount of filament.
    More importantly, there is nothing in the code at LAYER:57 that is any different than layers 1-56. There's no fault or error message, nothing.

    Does relative vs. exact extrusion play a role in the repair problem? It might explain the odd extrusion behavior when starting from E202+, but the default for repetier is absolute extrusion also and this weird stuff never happened.

    Moreover, It doesn't explain why it stopped and starts retracting really, really fast for a long time.

    For reference, here's the start of the file after editing:

    G21
    M107
    T0
    M104 S200
    M190 S60
    M109 S200
    G28
    G90
    G92 E0
    M82
    G0 F18000 X16.726 Y-11.512 Z14.8
    G0 ZZ17.096 Y-11.273
    ;TYPE:WALL-INNER
    G1 F2400 X17.697 Y-12.178 E202.49996
    G1 X18.337 Y-13.041 E202.59898

    Here's the start of the file before editing:

    G21
    M107
    T0
    M104 S200
    M190 S60
    M109 S200
    G28
    G90
    G92 E0
    M82
    G0 F18000 X37.246 Y-36.087 Z0.3
    G1 Z0.3
    G1 F6666 E0

    And here's the part between the last working and the failed layers:

    G1 F2400 X-35.2 Y-19.882 E9850.43843
    G1 F2400 X-31.68 Y-20.745 E9850.49042
    ; LAYER:57
    G0 F18000 X40.862 Y21.314 Z14.3
    G0 X40.74 Y20.889
    ; TYPE:WALL-INNER
    G1 F2400 X39.666 Y21.157 E9850.54145


  • administrators

    Editing files sliced with absolute extrusion is tricky because you need to make sure that after the lines you deleted, there are no G1 commands with an E parameter until after the next G92 E0 command. Use relative extrusion instead, it makes editing the files easier and technically it makes far more sense.

    My guess is that somewhere around layers 56 or 57 there is something that made a difference.


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