Purge more before changing extruder? Code?

  • This topic has 5 replies, 3 voices, and was last updated 4 years ago by Wim.
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  • #5787
    stefaan
    Participant

    How can I purge before the printer changes extruder?
    When I do a dual print and the top layers are a different color I want to purge more.

    Example at layer 15 the printer changes extruder but does not purge enough and I sometimes get underextrusion for a few seconds.

    ;LAYER:15
    G92 E0
    G1 F2400 E-8.00000
    G1 Z3.050
    ;Switch between the current extruder and the next extruder, when printing with multiple extruders.
    ;This code is added before the T(n)

    T0
    ;Switch between the current extruder and the next extruder, when printing with multiple extruders.
    ;This code is added after the T(n)
    G1 F500 E-0.5
    G1 F50 E0.5
    G92 E0
    G1 F3000 E-4.5
    G1 F12000

    G0 F12000 X95.904 Y151.546 Z3.200
    ;TYPE:WALL-INNER
    G1 Z3.200
    G1 F2400 E0.00000
    G1 F3000 X96.685 Y162.990 E0.15104
    G1 X96.657 Y163.373 E0.15609

    #5800
    roger uceda
    Moderator

    In start/end-gcode
    PostSwitchExtruder
    You can type:
    ;Switch between the current extruder and the next extruder, when printing with multiple extruders.
    ;This code is added after the T(n)
    G1 F500 E-0.5
    G1 F50 E0.8
    G92 E0
    G1 F4500 E-4.5
    G1 F{travel_speed}

    This way you will purge 0.8mm, set zero in the extruder, retract, and start printing.
    If you want extra purge, just modify it:
    ;Switch between the current extruder and the next extruder, when printing with multiple extruders.
    ;This code is added after the T(n)
    G1 F500 E-0.5
    G1 F50 E1.2
    G92 E0
    G1 F4500 E-4.5
    G1 F{travel_speed}

    #6039
    Wim
    Participant

    MAKE PURGE TIME DEPENDENT !
    The problem with changing the start/end gcode is :
    a) both extruders do the extra purge (if you want it just for one extruder)
    b) the extra purge of an extruder is not needed if the extruder was used shortly before, since it won’t have lost a lot of material.
    c) this takes much more time to print
    I think I might have a better solution (I had the same problem) :
    MAKE THE AMOUNT OF PURGE DEPENDENT ON THE TIME THE EXTRUDER WASN’T USED (IDLE), so :
    -> Purge more ONLY if the extruder wasn’t used for a long time (since it will have lost more material)
    -> Purge little if the extruder was used shortly before (since it didn’t loose that much material)

    This would be a far more better option resulting in less loss of material, faster, and more reliable prints
    Wim

    #6269
    stefaan
    Participant

    I change it in my gcode if I print somthing that uses the second extruder a lot later in the print.
    If I print something that changes printhead constantly it is not needed to purge extra.

    #6299
    Wim
    Participant

    Exactly, that’s why I proposed to change the software to make the extruder purge more when not used for a long time.
    In stead of having to change the gcode all the time.

    #6301
    Wim
    Participant

    I posted this on Github already as a feature request.

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