Modified Ender-3 behaves strangely when starting to print



  • Hello.

    I'm facing an issue, that I do not know how to solve.

    I have a Duet Wifi 1.02 board running the latest firmware
    that I have married with a printer based on Ender3, it has dual Z rods
    and a custom printhead. It has a 300mm Z height. The machine homes and calibrates
    fine, all axes move to right directions when moving the printhead/bed/Z
    through the web interface and it all seems fine.

    What is not fine, is that when start to print, there's some
    anomalies - like when I start a print job and straight after homing the
    printhead starts to move upwards, goes to very near the top
    and starts to move down pausing after every 10 seconds or so.

    I have a Duet3 machine as well, that I built - everything is
    fine there, I'm using the same slicer.

    Conf files are here: drive.google

    Any thoughts?



  • @Tanel_76

    M671 X-37:200 Y0:0 S10 ; Leadscrew at left connected to Z, leadscrew at right connected to E1
    M208 X0 Y0 Z0 S1 ; set axis minima
    M208 X235 Y235 Z300 S0 ; set axis maxima

    this does not make sene, this would place the second leadscrew inside your bed.

    M564 H0 ; Allow unhomed movement

    not a good idea to have this in your config.g

    G31 P500 X30 Y25 Z2.94 ; set Z probe trigger value, offset and trigger height
    M557 X15:215 Y15:195 S20 ; define mesh grid

    i would expect his to give you an error in the console about some points not being reachable.

    M308 S0 P"bed_temp" Y"thermistor" A"Build Plate" T100000 B4138 ; Set thermistor + ADC parameters for heater 0 Bed
    M308 S1 P"e0_temp" Y"thermistor" A"Nozzle" T100000 B4138 ; Set thermistor + ADC parameters for heater 1 HotEnd

    your thermistor config is wrong. B4138 is the default. look up the correct value in your thermistor documentation.

    G29 S1 ; Load previously set bed map

    this should be in your slicer start g code after the G28, because here you are loading the heightmap without establishing z=0

    your bed.g is incorrect for dual z leveling setup.
    see
    https://duet3d.dozuki.com/Wiki/Bed_levelling_using_multiple_independent_Z_motors
    on how to set up the bed.g

    post the beginning of a generated g code from your slicer



  • @Veti said in Modified Ender-3 behaves strangely when starting to print:

    @Tanel_76

    M671 X-37:200 Y0:0 S10 ; Leadscrew at left connected to Z, leadscrew at right connected to E1
    M208 X0 Y0 Z0 S1 ; set axis minima
    M208 X235 Y235 Z300 S0 ; set axis maxima

    this does not make sene, this would place the second leadscrew inside your bed.

    The z leadscrew position coordinates are a bit of mystery to me.
    When looking at some examples, would the correct setup be:

    File config.g:

    M584 X0 Y1 Z2:4 E3; two Z motors connected to driver outputs Z and E1
    M671 X-20:255 Y0:0 S0.5 ; leadscrews at left (connected to Z) and right (connected to E1) of X axis
    M208 X-0:235 Y0:235 ; X carriage moves from 0 to 235, Y bed goes from 0 to 235.

    and File bed.g:

    G28 ; home
    G30 P0 X20 Y100 Z-99999 ; probe near a leadscrew, half way along Y axis
    G30 P1 X180 Y100 Z-99999 S2 ; probe near a leadscrew and calibrate 2 motors

    When assuming, that the Z1 and Z2 leadscrews are positioned -20mm from X0 and
    +20mm of Xmax, which is 235?

    M564 H0 ; Allow unhomed movement

    not a good idea to have this in your config.g

    Without M564 H0 I could not home. Got an error immediately.

    G31 P500 X30 Y25 Z2.94 ; set Z probe trigger value, offset and trigger height
    M557 X15:215 Y15:195 S20 ; define mesh grid

    Yes, the first row was not reachable, that I know.

    i would expect his to give you an error in the console about some points not being reachable.

    M308 S0 P"bed_temp" Y"thermistor" A"Build Plate" T100000 B4138 ; Set thermistor + ADC parameters for heater 0 Bed
    M308 S1 P"e0_temp" Y"thermistor" A"Nozzle" T100000 B4138 ; Set thermistor + ADC parameters for heater 1 HotEnd

    your thermistor config is wrong. B4138 is the default. look up the correct value in your thermistor documentation.

    I tweaked the thermistor settings a lot and the default was the only value, where I did not get errors
    during heat up.

    G29 S1 ; Load previously set bed map

    OK, I will delete that.

    this should be in your slicer start g code after the G28, because here you are loading the heightmap without establishing z=0
    your bed.g is incorrect for dual z leveling setup.
    see
    https://duet3d.dozuki.com/Wiki/Bed_levelling_using_multiple_independent_Z_motors
    on how to set up the bed.g
    post the beginning of a generated g code from your slicer



  • @Tanel_76 said in Modified Ender-3 behaves strangely when starting to print:

    M208 X-0:235 Y0:235 ; X carriage moves from 0 to 235, Y bed goes from 0 to 235.

    isnt the ender 3 bed 225?

    Without M564 H0 I could not home. Got an error immediately.

    then you have a different problem. what error?

    I tweaked the thermistor settings a lot and the default was the only value, where I did not get errors
    during heat up.

    did you use the values from the ender guide?
    https://duet3d.dozuki.com/Guide/Ender+3+Pro+and+Duet+Maestro+Guide+Part+2:+Configuration/38



  • The Ender 3 has an advertised and usable print area of 220 x 220 mm. However, the size of the print build surface actually measures 235 x 235 mm.

    I did not use the Ender 3 Pro Duet Maestro settings, I generated my settings in reprap configurator,
    I have a bit different machine with PINDA2 sensor and dual Z motors.

    I think I got an "insufficient axes homed" or just nothing, no movement at all
    without M564 H0.



  • @Tanel_76 said in Modified Ender-3 behaves strangely when starting to print:

    The Ender 3 has an advertised and usable print area of 220 x 220 mm. However, the size of the print build surface actually measures 235 x 235 mm.

    you are correct. then the x coordinates seem ok.

    I think I got an "insufficient axes homed" or just nothing, no movement at all
    without M564 H0.

    you get insufficient axes homed when executing homeall? post your homeall.g



  • This is my operational M671 on my ender-3 with dual lead screws

    M671 X-25:260 Y115:115 S5 ; Z Axis lead screw locations in relation to the X axis

    I have an operational config.g if you want a copy



  • @Tanel_76 said in Modified Ender-3 behaves strangely when starting to print:

    G28 ; home
    G30 P0 X20 Y100 Z-99999 ; probe near a leadscrew, half way along Y axis
    G30 P1 X180 Y100 Z-99999 S2 ; probe near a leadscrew and calibrate 2 motors

    Hi,
    I would like to see it, if possible.
    I got the machine to properly do the x-gantry calibration, now
    next thing to do is to the mesh compensation, after that I will try
    to print the test cube again.



  • Ender-3 dual leadscrew bed.g

    G28                         ; home
    G30 P0 X3 Y115 Z-99999      ; probe near the left lead-screw
    G30 P1 X200 Y115 Z-99999 S2 ; probe near the right lead-screw 
    G30 P0 X3 Y115 Z-99999      ; probe near the left lead-screw for the second time
    G30 P1 X200 Y115 Z-99999 S2 ; probe near the right lead-screw for the second time
    G91                         ; Relative positioning
    G1 H2 Z5 F8000              ; Lift the Z axis relative to its current position
    G90                         ; Absolute positioning
    G1 X105 Y105 F6000          ; Go to the centre of the bed
    G30                         ; Home the Z axis
    G91                         ; Relative positioning
    G1 Z5 F1000                 ; Lift the Z axis relative to its current position
    G90                         ; Absolute positioning
    


  • This post is deleted!


  • Got the machine calibrated,
    it's homing fine, when starting to print, it homes all,
    then starts immediately move upwards, until Z145
    then waits and starts to come back towards the bed slowly.

    Strange.


  • Moderator

    Post your homeall and homez.

    Post your slicer start gcode.

    Do you also have a start.g file in your system folder?



  • Hi,

    I threw the start.g out, after that the anomalies disappeared.

    The only issue is now the Z height, I have calibrated and reset the (G92 Z0)
    got the trigger height 2.4 and I have it in mu config.g
    Still, when starting to print, the nozzle goes like 4.5mm downwards
    from the calibrated height.

    I deleted the slicer start code (the initial line in Cura)
    just to see, what's happening.


  • Moderator



  • Homeall
    homez.g

    I think these are pretty standard.



  • @Tanel_76 said in Modified Ender-3 behaves strangely when starting to print:

    got the trigger height 2.4 and I have it in mu config.g

    post you new config, you might have made a mistake



  • The last conf file is here:
    https://pastebin.com/npPJ2iSK

    It's basically the same conf.g that I had uploaded earlier,
    I just changed the M671 and also thermistor settings.

    I copied the CaLviNx bed.g that he generously posted here.

    When I start a print job, the nozzle goes down about 4.5mm,
    I also recalibrated the Z height about 5 times,
    the drop in Z height was constant every time.



  • @Tanel_76

    so when you enter G28

    and move to G0 Z0 then nozzle is above the bed?



  • @CaLviNx said in Modified Ender-3 behaves strangely when starting to print:

    I have an operational config.g if you want a copy

    Is it possible to see the conf.g that you are using?



  • @Veti said in Modified Ender-3 behaves strangely when starting to print:

    @Tanel_76

    so when you enter G28

    and move to G0 Z0 then nozzle is above the bed?

    No, and that's the strange thing. after resetting Z
    I go G1 Z100 F400 and come down to G1 Z5 F400
    the nozzle ploughs into the bed. When I move
    down step by step, I see that the nozzle is above the
    bed around Z55 which is not logical at all.

    It's as if the G92 Z0 value is not entered correctly
    and the Duet gets another value from somewhere,
    which I can't find.

    PS Im using this guide
    https://duet3d.dozuki.com/Wiki/Test_and_calibrate_the_Z_probe#:~:text=In Duet Web Control%2C go,Save the file.

    And Duet seems to have the same symptoms, as if when you forget the M500 command after resetting Z in Marlin.
    I have to go to config-override.g and check that there are no G31 commands, when I'm near the printer again.



  • issue the G31 command to see if the duet got your offset set.


  • Moderator

    Where are you sending G92 Z0? I don't see that anywhere in your homing files.

    G90 ; absolute positioning
    G1 X-5 Y-5 F6000 ; go to first bed probe point and home Z
    G30 ; home Z by probing the bed

    Also, from your homing files the G1 XY move makes no sense. It looks like it's just pushing it into the corner? The choice of an absolute negative value seems odd since your M208 minimum doesn't allow negative positions.

    Regardless. You should choose a position that places the probe at the center of the bed.

    Also, remove M564 H0 ; Allow unhomed movement from your config just to make sure it's not allowing moves that would otherwise fail. It can be hiding issues that should be fixed.


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