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    Z axis gets reset to zero before print starts

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    • wifibeagleundefined
      wifibeagle
      last edited by

      I have a curious problem that appeared after changing back to a standard V6 clone from a dragon hotend. When I start a print the Z axis zero gets reset before the first movement. Then it air prints about 35mm above the bed. If I add a short pause (G4 S1) to the gcode file before the initial movement command it prints normally. I am currently using Cura 5.0 slicer with no additional starting gcode commands. Initially my start.g file was unchanged. I have tried several additions and deletions to that file without success. Including or excluding the wipe macro had no effect.

      Any suggestions? Editing the gcode file every time is a pain.

      The printer is a custon coreXY with a Duet3 and a single rev1 toolboard. It has 3 Z axis steppers for bed leveling. I have been running release 3.3 before and after the hotend switch. My Z probe has been a Precision Piezo Orion throughout.

      echo "start.g executing"
      M220 S100 ; reset speed factor
      M557 X35:285 Y35:285 S50 ; define default mesh grid
      G1 Z35.0 F1000 ; Move the platform down to 35mm
      ;G92 E0 ; reset extruder
      ;G1 X150 Y0 F6000
      ;G29 S0
      ;M376 H3
      ;G1 E5 F100 ; Extrude a short distance before wipe
      M98 P"0:/macros/wipe"
      ;G4 S1 ; wait then beep
      M300 S500 P500
      G4 S1

      wipe macro
      if !move.axes[0].homed || !move.axes[1].homed || !move.axes[2].homed
      exit

      if move.axes[2].machinePosition < 35
      G1 Z35 F500

      G1 X-15 Y20 F6000

      while iterations < 4
      M280 P4 S115
      G4 S0.2
      M280 P4 S80
      G4 S0.2
      continue

      M280 P4 S20

      Typical starting section of the gcode file
      ;FLAVOR:RepRap
      ;TIME:1838
      ;Filament used: 7.81383m
      ;Layer height: 0.35
      ;MINX:103.875
      ;MINY:90.082
      ;MINZ:0.35
      ;MAXX:144.943
      ;MAXY:219.915
      ;MAXZ:17.85
      ;Generated with Cura_SteamEngine 5.0.0
      T0
      M190 S70
      M104 S245
      M109 S245
      M82 ;absolute extrusion mode

      M83 ;relative extrusion mode
      G1 F1800 E-1
      ;LAYER_COUNT:51
      ;LAYER:0
      M107
      M204 T1500
      M566 X1200 Y1200
      G4 S1
      G0 F7200 X105.327 Y92.253 Z0.35
      G0 X103.876 Y96.79
      M204 P1000
      M566 X2100 Y2100
      ;TYPE:SKIRT
      G1 F1500 E1
      G1 F1800 X103.886 Y96.111 E0.07411

      Reference files
      config-g-6-14-22.txt
      M122.txt
      M122-B121.txt

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      • Phaedruxundefined
        Phaedrux Moderator
        last edited by

        Is it homing correctly?

        When exactly is the z axis getting set to 0?

        @wifibeagle said in Z axis gets reset to zero before print starts:

        appeared after changing back to a standard V6 clone from a dragon hotend.

        @wifibeagle said in Z axis gets reset to zero before print starts:

        My Z probe has been a Precision Piezo Orion throughout.

        The piezo depends on the rigidity and weight of the hotend. Perhaps when changing the hotend it's characteristics changed and it's triggering early in the homing move?

        Z-Bot CoreXY Build | Thingiverse Profile

        wifibeagleundefined 1 Reply Last reply Reply Quote 0
        • wifibeagleundefined
          wifibeagle @Phaedrux
          last edited by

          @phaedrux Thank you for your suggestions.

          There is no problem homing, zeroing the Z axis, G32 bed leveling or probing to verify the bed leveling.

          The reset seems to occur with the first slight XY move at the start of a print. Then a short delay, less than a second, Z zero reset and the start of the air print. It all happens so fast it is hard to tell the exact behavior. I would not expect the Z probe to be active at this time.

          There is a slight sensitivity difference for the piezo after the hotend change. It seems slightly less sensitive than before. Translating between probe locations at 6000mm/min there are frequent probe triggers. I have a 0.8 second delay between motion and the start of a probe. That has eliminated false trigering. Reducing the acceleration during probing also helped but not as much as the delay.

          I upgraded to 3.4.1 yesterday for other reasons. I will try a print today without adding the G4 delay and see if the problem persists.

          John

          wifibeagleundefined 1 Reply Last reply Reply Quote 0
          • wifibeagleundefined
            wifibeagle @wifibeagle
            last edited by

            @wifibeagle
            Reprinted a part that required the G4 delay after deleting that command. No problems with the print. It appears 3.4.1 may have cured the problem even if it has not completely solved the mystery.

            I can live with that!

            1 Reply Last reply Reply Quote 1
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