Duet Wifi Bowden Extruder skipping.



  • Hi everyone. I am new to the Deut family but I am already in love with it. I bought a Duet wifi because a stepper driver on the clone control board for my FLsun delta printer died.

    I had no issues setting things up mechanically and getting the first auto calibration done was a bit of a hassle but I got it to calibrate and it was repeatable within 2 revisions. The issue I am having now is when I went to do my first print the extruder started skipping quite bad after a few seconds. I followed a few extruder calibration things but they seem to make no real difference.

    If I try to send a g1 E100 F90 code it skips after about 30mm of filament being pulled into the extruder gears. If I half the feed rate to F45, it never skips but it also never stops extruding. Changing the E steps/mm seems to make no appreciable difference. My printer setup is a non geared, bowden extruder feeding into an E3d V6.

    Any help would be greatly appreciated.



  • Hi and welcome.

    It does sound rather like your extruder steps per mm are dramatically out. What are they set too and how did you arrive at the setting? For an E3D geared extruder the steps are in the order of about 400 so for a non geared extruder, I'd expect to see around 1/3rd of this - say 130 but it depends on very many factors (diameter of the hobbed bolt, filament size etc).
    Ian
    Edit. What happens if you try feeding filament through the web interface? With the hot end connected and heated, you won't able to user much more than 5 or 10 mm/sec, with the hot end disconnected, you will be able to use higher speeds.



  • This is my M92 line: M92 X100 Y100 Z100 E150 It is at 150 but it made no difference when it was lower. I have been doing everything through the web interface. I measured the hobbed gear and is measured at 6.5mm. what do you mean feeding filament with the hot end disconnected? as in physically disconnected?



  • @lolmodule:

    ….......................what do you mean feeding filament with the hot end disconnected? as in physically disconnected?

    Yes. On the web interface you have speeds of 5, 10, 20 40 and 60 mm/sec. With hot end heated, you'll only be able to use 5 or 10 mm/sec because that's a fast as you can reasonably melt filament (it depends a bit on your hot end - an E3d volcano might be able to do a bit better). So if you try and use the higher speeds, the extruder will skip steps and/or grind the filament because you will be trying to force it through the hot end faster than it can be melted. The higher speeds are only there for loading and unloading filament.

    Edit. Just re-read your original post - trying to feed the filament through the hot end at 90mm/sec isn't going to work for the reasons given above. I'm surprised that you could feed it at 45mm/sec. The mystery now is why it never stops. How long have it left it extruding for?


  • administrators

    The F values in the G1 command are not mm/s but mm/ minute:
    https://duet3d.com/wiki/G-code#G0_.26_G1:_Move

    So F90 is slow.

    Lolmodule; we need to see your config.g and some details about your extruder gearing in order to help.



  • Thanks for the responses guys. Here is a picture of the extruder I am using. ( I cant remember what it is called)

    Here is my config.g:

    ; Think3DPrint3D configuration file for Mini Kossel for testing Duet WiFi

    ; Communication and general
    M111 S0 ; Debug off
    M550 My Delta ; Machine name and Netbios name (can be anything you like)
    M551 Preprap ; Machine password (used for FTP)
    ;*** If you have more than one Duet on your network, they must all have different MAC addresses, so change the last digits
    M540 P0xBE:0xEF:0xDE:0xAD:0xFE:0xED ; MAC Address
    ;*** Wifi Networking
    M552 S1 ; Enable WiFi. Disabled for setup and testing. Enable once set up on your network.

    M555 P2 ; Set output to look like Marlin
    M575 P1 B57600 S1 ; Comms parameters for PanelDue

    G21 ; Work in millimetres
    G90 ; Send absolute coordinates…
    M83 ; ...but relative extruder moves

    ; Axis and motor configuration
    M569 P0 S1 ; Drive 0 goes forwards
    M569 P1 S1 ; Drive 1 goes forwards
    M569 P2 S1 ; Drive 2 goes forwards
    M569 P3 S0 ; Drive 3 goes forwards
    M569 P4 S1 ; Drive 4 goes forwards
    M574 X2 Y2 Z2 S2 ; set endstop configuration (all endstops at high end, active high)
    ;*** The homed height is deliberately set too high in the following - you will adjust it during calibration
    M665 R99.558 L211.639 B85 H262.325 ; set delta radius, diagonal rod length, printable radius and homed height
    M666 X1.28 Y-1.54 Z0.26 ; put your endstop adjustments here, or let auto calibration find them
    M350 X16 Y16 E16 I1 ; Set 16x microstepping with interpolation
    M92 X100 Y100 Z100 E150 ; Set axis steps/mm
    M906 X1000 Y1000 Z1000 E1500 I60 ; Set motor currents (mA) and increase idle current to 60%
    M201 X1000 Y1000 Z1000 E1000 ; Accelerations (mm/s^2)
    M203 X20000 Y20000 Z20000 E3600 ; Maximum speeds (mm/min)
    M566 X1200 Y1200 Z1200 E1200 ; Maximum instant speed changes mm/minute

    ; Thermistors
    M305 P0 T100000 B3950 R4700 H30 L0 ; Put your own H and/or L values here to set the bed thermistor ADC correction
    M305 P1 T100000 B4388 R4700 H30 L0 ; Put your own H and/or L values here to set the first nozzle thermistor ADC correction
    M305 P2 T100000 B3974 R4700 H30 L0 ; Put your own H and/or L values here to set the second nozzle thermistor ADC correction
    M570 S180 ; Hot end may be a little slow to heat up so allow it 180 seconds

    ; Fans
    M106 P1 H-1 ; disable thermostatic mode for fan 1

    ; Tool definitions
    M563 P0 D0 H1 ; Define tool 0
    G10 P0 S0 R0 ; Set tool 0 operating and standby temperatures
    ;*** If you have a single-nozzle build, comment the next 2 lines
    ;M563 P1 D1 H2 ; Define tool 1
    ;G10 P1 S0 R0 ; Set tool 1 operating and standby temperatures
    M92 E663:663 ; Set extruder steps per mm

    ; Z probe and compensation definition
    ;*** If you have a switch instead of an IR probe, change P1 to P4 in the following M558 command
    M558 P4 X0 Y0 Z0 H4 ; Z probe is an IR probe and is not used for homing any axes
    G31 X0 Y0 Z0 P500 ; Set the zprobe height and threshold (put your own values here)

    ;*** If you are using axis compensation, put the figures in the following command
    M556 S78 X0 Y0 Z0 ; Axis compensation here

    M208 S1 Z-0.2 ; set minimum Z
    ;
    T0 ; select first hot end



  • You have M92 E663.663 in the "tool definitions" section which is ultimately setting your steps/mm at 663.663 as it comes after the 1st one.

    In my config I set the E steps in that same tool section, so to copy what I did.. remove the E150 from the initial M92 command (the one that is in the "axis and motor defenition" section, and change the figure in the last M92 ("tool definitions") to be what you think it is, which 150 would seem a reasonable starting point just from the picture of your extruder.

    With it set to 663 steps per mm which is probably 4.3 times more that it should be.. and you attempting to extrude 100mm at a time, no doubt it would have felt like it would never stop! (it may have done almost 1/2 meter of extrusion lol)

    disconnect your bowden tube from the output of the extruder…start with smaller 10mm test lengths and measure how much comes out from extruder into free air and adjust your E steps until its close to 10mm, only then move up to a larger amount like 50mm

    FYI, in actual real world prints.. the extrusion feed rate is really quite slow.. as an example a print I am about to do with movement speeds of 65mm/s (woefully inadequate measurement of printing speed), simplify 3d tells me the filament usage is 12504.6mm .. and it will take 1hr 34mins. that works out to an average feedrate of around 2.14 mm/s going through the extruder. Sure that's a very crude and simplistic calculation, not taking into account retraction etc etc.. but it still gives a rough idea of the sort of average speed the extruder works at..



  • @Crash69:

    You have M92 E663.663 in the "tool definitions" section which is ultimately setting your steps/mm at 663.663 as it comes after the 1st one.

    HOW did I miss that! I will change that now and run a few small extruder tests like you suggest and come back with an update. Thank you so much!



  • Update: Took a few runs through to whittle down the right steps for the extruder. printed a calibration cube and it had a few issues but they weren't the fault of the printer. I tweaked a few settings in slicer and the cube turned out almost perfect. Thanks so much for the help!



  • @lolmodule:

    I tweaked a few settings in slicer and the cube turned out almost perfect. Thanks so much for the help!


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