At end of print a huge retraction occurs



  • (where this did not used to happen)

    Hi,

    I just swapped in a new (well second hand) PC and now find that with the new cura I installed (3.3 v wanhao 16.021) at the end of the print a massive filament extraction occurs like 100s of mm which once the molten filament cools in the cold end blocks the Microswiss coldend/hotend "tube" necessitating me removing the assembly every time and using a burner on it it get the PLA plug out. So I am struggling to find out why this dumb action occurs. Is there anything in the duet wifi config ie X.g files that would cause this?

    Also before the PC upgrade at the end of the print the part cooling fans would stop, not any more. Plus the head doesnt move to the mins any more it just stays where it finished.

    There is end gcode but its like its ignored.

    ;wanhao-d6 - ssj
    ;M104 S0
    ;M140 S0
    ;Retract the filament
    ;G92 E1
    ;G1 E-1 F300
    ;G28 X0 Y0
    ;M84
    ;End GCode
    M104 S0 ;extruder heater off
    M140 S0 ;heated bed heater off (if you have it)
    G91 ;relative positioning
    G1 E-0.25 F300 ;retract the filament a bit before lifting the nozzle, to release some of the pressure
    G1 Z+0.5 E-0.25 X-20 Y-20 F{travel_speed} ;move Z up a bit and retract filament even more
    G28 X0 Y0
    G90
    G1 Z160 ;move X/Y to min endstops, so the head is out of the way
    M84 ;steppers off
    G90 ;absolute positioning

    any ideas pls?



  • I'm gonna guess that when you installed the new cura you didn't enable relative extrusion, so when the G1 E-0.25 command goes it tries to retract all the way back to the start of the print.

    Either unhide the Relative Extrusion toggle in the Special Moves section, or add M83 to your start code to use relative extrusion.


  • administrators

    Add M83 to your end gcode before the G1 E-0.25 command.



  • Hmm yes and no.

    I did find that so added it.

    So this morning I printed 5 computer feet, printed perfectly.

    Did a second lot and it "power extracted" again. Here is the actual gcode end pulled from the duet wifi that just failed. I am not sure how much its etracting but its enough to push out the PTFE tube and show about 25mm, so I'd guess 50mm+.

    =====
    8><----
    G1 X16.802 Y104.254
    G0 F7200 X18.74 Y101.75
    G1 F1950 X21.88 Y98.61 E639.39334
    G1 X21.95 Y98.54
    ;TIME_ELAPSED:19197.090754
    G1 F1800 E637.99334
    M107
    ;M104 S0
    ;M140 S0
    ;Retract the filament
    ;G92 E1
    ;G1 E-1 F300
    ;G28 X0 Y0
    ;M84
    ;End GCode
    ;ssjM104 S0 ;extruder heater off
    ;ssjM140 S0 ;heated bed heater off (if you have it)
    ;ssjG91 ;relative positioning
    ;ssj G1 E-0.25 F300 ;retract the filament a bit before lifting the nozzle, to release some of the pressure
    ;ssj G1 Z+0.5 E-0.25 X-20 Y-20 F{travel_speed} ;move Z up a bit and retract filament even more
    ;ssjG28 X0 Y0
    ;ssjG90
    ;ssj G1 Z160 ;move X/Y to min endstops, so the head is out of the way
    ;ssjM84 ;steppers off
    ;ssj G90 ;absolute positioning

    ;ssj try 2 may2018
    ;End GCode
    M104 S0 ;extruder heater off
    M140 S0 ;heated bed heater off (if you have it)
    G91
    M83 ;relative positioning
    G1 E-1 F300 ;retract the filament a bit before lifting the nozzle, to release some of the pressure
    G1 Z+0.5 E-1 X-20 Y-20 F{travel_speed} ;move Z up a bit and retract filament even more
    G28 X0 Y0
    G90
    G1 Z170 ;move X/Y to min endstops, so the head is out of the way
    M84 ;steppers off
    G90 ;absolute positioning
    ;{profile_string}
    M106 S0
    M82 ;absolute extrusion mode
    M104 S0
    ;End of Gcode



  • @phaedrux thanks for this. I put my old harddrive in the new machine and pulled off the settings and Wanhoa's Cura 16.01 had M83 and when I had upgraded it with 16.021 it must have loaded the old profile. When I re-installed 16.021 the M83 was indeed missing so when copied to 3.3 as end code, oopsie. However I am still have strange problems.



  • I have clean up the end this is now what I have,

    8><---
    G1 X16.802 Y104.254
    G0 F7200 X18.74 Y101.75
    G1 F1950 X21.88 Y98.61 E639.39334
    G1 X21.95 Y98.54
    ;TIME_ELAPSED:19197.090754
    G1 F1800 E637.99334
    M107

    ;ssj try 6 may2018
    G91
    M83 ;relative positioning
    G1 E-0.25 F300 ;retract the filament a bit before lifting the nozzle, to release some of the pressure
    G1 Z+0.25 E-1 X-20 Y-20 F{travel_speed} ;move Z up a bit and retract filament even more
    G28 X0 Y0
    G90
    G1 Z170 ;move X/Y to min endstops, so the head is out of the way
    M84 ;steppers off
    G90 ;absolute positioning
    M106 S0
    M104 S0 ;extruder heater off
    M140 S0 ;heated bed heater off (if you have it)
    M82 ;absolute extrusion mode
    M104 S0
    ;End of Gcode

    if this stuffs up maybe I need a new sd card?



  • @gzcwnk said in At end of print a huge retraction occurs:

    G1 F1800 E637.99334

    Is that part of your end code or from Cura? That's the only large extruder move.



  • Yeah I assume that's the end where ist making the parts. i am at 97% so I am going to watch it finish, see if it goes mad. Might try videoing it.



  • @phaedrux "That's the only large extruder move." hence I am so confused I cant see why. Might install a Cura 2.x version if this continues.



  • Could you please attach the complete gcode file, that would be more useful than just the fragment shown. Thanks.



  • Hi, thanks. I am currently running another print. Its probably user error on my part, but if it stuffs up I wont know why (last print was perfect) so I'll upload the gcode off the printer directly.


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