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    Triple Z / Stall detection and DWC failure ....

    Tuning and tweaking
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    • Garfield
      Garfield last edited by

      So I don't know where to put this particular post.

      I've been having some issues getting my Z axis sorted 'satisfactorily'. The printer is a coreXY, the controller a Duet3 on RC2 firmware, 2.0.7 DWC.

      I have two kinds of 'homing' for Z.

      1 : Drives the bed to its lowest position, hard stops all three Z steppers which synchronises them where the bed is 'mechanically' levelled - how I do this is a different topic.

      2 : Sets print level using three axis bed levelling (Kinematic mounted bed).

      My problem is with number 1. I cannot set a stall current that works - S2 is too sensitive, S3 is not sensitive enough - I really need the system to tell me what current it thinks that it is seeing because I have the printer running on a lab PSU whilst setting up and the current never even gets close to the rated current of a single stepper let alone three of them.

      My next problem can be seen in the following image - details follow the image

      DWC Homing Error.png

      First off - I didn't cancel so G28 Z Error I don't understand.

      next the text below it does not exist in ANY of my homing GCODE - not in homez.g nor homeall.g

      next - X and Y are homed - why the error - you can't home Z unless they are

      next yet again the text below does not exist in ANY of my homing GCODE - not in homez.g nor homeall.g, nor the gcode below that.

      Then the stack overflow, then the failed.

      These are my homez and homeall - as you can see nowhere does the text reported exist .. so where is it from - it is not my code so how can it be cancelled !!!

      ; homez.g
      
      G91                ; relative positioning
      ; G1 H2 Z5 F1600    ; lift Z relative to current position
      G1 H1 Z320 F1800   ; move Z down until the endstop is triggered
      G92 Z320           ; set Z position to axis maximum 
      G1 H2 Z5 F100
      
      ; homeall.g
      ; called to home all axes
      ;
      G91                     ; relative positioning
      G1 H1 X-320 F1000 ; coarse home X
      G1 X4 F600 ; move away from the X endstop
      G1 H1 X-10 F250 ; fine home X
      G92 X-157
      G1 H1 Y-320 F1000 ; coarse home Y
      G1 Y4 F600 ; move away from the Yendstop
      G1 H1 Y-10 F250 ; fine home Y
      G92 Y-127
      G1 H1 Z330 F1600 ; coarse home Z
      G1 H1 Z-4 F330
      G1 H1 Z330 ; fine home Z
      G92 Z320
      G1 H1 X0 Y0 F360 ; move nozzle to centre of bed
      G90                     ; absolute positioning
      
      
      dc42 1 Reply Last reply Reply Quote 0
      • dc42
        dc42 administrators @Garfield last edited by

        @Garfield said in Triple Z / Stall detection and DWC failure ....:

        My problem is with number 1. I cannot set a stall current that works - S2 is too sensitive, S3 is not sensitive enough

        • Typically you need to use M913 to reduce the motor current while doing stall-detect homing.
        • Additionally, Z steps/mm values are often too high for stall detect homing to work.
        • The sequences starting M120 and ending M121 are what DWC sends when you press the buttons to jog the axes.
        • The Homing Failed message means that a stall wasn't detected before the G1 H1 Z command in homez.g completed.

        Duet WiFi hardware designer and firmware engineer
        Please do not ask me for Duet support via PM or email, use the forum
        http://www.escher3d.com, https://miscsolutions.wordpress.com

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        • Garfield
          Garfield last edited by

          Well that explains the push and pop because I tried to move the axis after the failure - the steppers were unresponsive.

          dc42 1 Reply Last reply Reply Quote 0
          • dc42
            dc42 administrators @Garfield last edited by

            @Garfield said in Triple Z / Stall detection and DWC failure ....:

            Well that explains the push and pop because I tried to move the axis after the failure - the steppers were unresponsive.

            Probably because homing failed, and by default regular axis movements are not allowed until homing has been done.

            Duet WiFi hardware designer and firmware engineer
            Please do not ask me for Duet support via PM or email, use the forum
            http://www.escher3d.com, https://miscsolutions.wordpress.com

            1 Reply Last reply Reply Quote 1
            • Garfield
              Garfield last edited by Garfield

              Well I'll be, I'm officially dumb as a box of rocks - it works - can you explain how the current reduction works ?

              Is this a reduction in the actual current or the detection - seems a bit counter intuitive - I was reading all the stuff about how too slow and such is a problem.

              Just trying to understand without code diving.

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