Strange Extruder Behaviour afer upgrade to DuetWifi

  • Hi,

    Today i got my nice upgrade from my old 8bit board in my Delta printer.
    Installed everthing..config was easy and then i startet the first test print. A Calibration cube. leveling looks fine..printer starts with a good line..but then the E0 starts to become faster and faster..on second layer the nozzle is already diggin in a fat plastic line šŸ˜ž

    Took the Steps from my old marlin config.h were 96 so i used it here too..did a extruder calibration and after that i should set the steps per mm higher ??

    so why the extruder gets faster??

  • problably because you sliced with absolute extrusion (M82) and must use relative extrusion (M83)ā€¦

  • thats the starting code that Cura uses
    ;Sliced at: {day} {date} {time}
    ;Basic settings: Layer height: {layer_height} Walls: {wall_thickness} Fill: {fill_density}
    ;Print time: {print_time}
    ;Filament used: {filament_amount}m {filament_weight}g
    ;Filament cost: {filament_cost}
    ;M190 S{print_bed_temperature} ;Uncomment to add your own bed temperature line
    ;M109 S{print_temperature} ;Uncomment to add your own temperature line
    G21 ;metric values
    G90 ;absolute positioning
    M107 ;start with the fan off
    G28 ;move to endstops
    G92 E0 ;zero the extruded length
    G1 F200 E2 ;extrude 3mm of feed stock
    G92 E0 ;zero the extruded length again
    G1 F{travel_speed}
    ;Put printing message on LCD screen
    M117 Printingā€¦

    anyway..tried it again with the default value Steps/mm for E0 even worser..extruder stepper starts slow and speed up until i had to shutdown the printer

  • you must include M82 in your start code to tell the Duet you are using absolute extrusion, by default it is set to relative extrusion (M83)

  • thats in my config.g

    ; General preferences
    M111 S0 ; Debugging off
    G21 ; Work in millimetres
    G90 ; Send absolute coordinatesā€¦
    M83 ; ...but relative extruder moves
    M555 P2 ; Set firmware compatibility to look like Marlin
    M665 R105.6 L215 B90 H307 ; Set delta radius, diagonal rod length, printable radius and homed height
    M666 X0 Y0 Z0 ; Put your endstop adjustments here, or let auto calibration find them
    M208 Z0 S1 ; Set minimum Z

    so M83 is active

  • just put M82 in your cura start codeā€¦

  • yes..thats was the config.g it was a M83..exchanged it to a M82 and its ok now..just small tweaks left to do

    Thx for your competend and fast help šŸ˜‰

  • really strangeā€¦i change the M83 to a m82 in the config..first print was done and the printer retracted all the filament i had to put a g83 in the end.code from cura..
    had never such problems on the marlin 8 bit

  • administrators

    The alternative fix would have been to put G92 E0 prior to the G1 E command that is retracting filament at the end if your print. That G1 E command might be in your slicer end gcode, or in your stop.g file if you have one.

    We recommend using relative extruder coordinates. Recent versions of Cura support it, and every other slicer I know of has done so for years.

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