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    Z trigger height

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    • FelixHundefined
      FelixH
      last edited by

      Hi all,

      Probably a very silly question, but I am in doubt right now, so please bear with me...

      On my Marlin Machines, I use the following start G-Code to set the Z-Probe Offset:

      M851 Z-0.32 ; set z probe offset
      

      On my Duet machines, I have the value hard-coded to the config.g file.

      My question is: can I also set the probe offset on the start G-Code also on the Duet Machines? I am assuming that much, but I just want to be sure...

      BTW: I know that on Duet is called Trigger Height and is calculated differently...

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      • Vetiundefined
        Veti
        last edited by

        yes you can issue the G31 command just like the M851 in marlin

        FelixHundefined 1 Reply Last reply Reply Quote 0
        • FelixHundefined
          FelixH @Veti
          last edited by

          @Veti thanks for the confirmation. If I add it on the initial Gcode, I can adjust it more rapidly, without having to reboot the board.

          Vetiundefined fcwiltundefined 2 Replies Last reply Reply Quote 0
          • Vetiundefined
            Veti @FelixH
            last edited by

            @FelixH

            I can adjust it more rapidly

            yes it takes effect without rebooting, but you need to do a new home

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            • Phaedruxundefined
              Phaedrux Moderator
              last edited by

              Perhaps using baby stepping would be more appropriate, then you wouldn't need to rehome.

              https://duet3d.dozuki.com/Wiki/Gcode#Section_M290_Baby_stepping

              Z-Bot CoreXY Build | Thingiverse Profile

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              • fcwiltundefined
                fcwilt @FelixH
                last edited by

                @FelixH said in Z trigger height:

                @Veti thanks for the confirmation. If I add it on the initial Gcode, I can adjust it more rapidly, without having to reboot the board.

                I have a pair of macros (print_begin.g and print_end.g) that are called (using M98) by settings in the slicers I use.

                Two of the things that happen in print_begin.g are a call to a macro configprobe.g and then a call to a macro probez.g

                The Z trigger height setting happens in configprobe.g using G31.

                So if I need to change it, I just edit the file and then subsequent prints use the new settings.

                No need to re-boot, no need to home.

                Frederick

                Printers: a E3D MS/TC setup and a RatRig Hybrid. Using Duet 3 hardware running 3.4.6

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                • FelixHundefined
                  FelixH
                  last edited by

                  Thank you all for your inputs.

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                  • FelixHundefined
                    FelixH
                    last edited by

                    Is there any kind of trick on finding out the correct trigger height? Any time I have to re-calibrate is like a trip to hell. After following this guide:

                    https://duet3d.dozuki.com/Wiki/Test_and_calibrate_the_Z_probe

                    I get, for example, a trigger height of 1.50mm. I set it on the config.g file and I do a test. The nozzle is way too far from the bed and I try to use Babystepping to get it closer. The Babystepping shows me a -0.15 (for example)... now what? Should I correct the config.g file and set the trigger height to 1.35 (1.5-0.15) ??

                    Phaedruxundefined fcwiltundefined 2 Replies Last reply Reply Quote 0
                    • Phaedruxundefined
                      Phaedrux Moderator @FelixH
                      last edited by

                      @FelixH said in Z trigger height:

                      Should I correct the config.g file and set the trigger height to 1.35 (1.5-0.15) ??

                      If it's consistent, yes.

                      If you do the G30 S-1 test multiple times over does it give a consistent result? Are you also homing in that same spot?

                      Z-Bot CoreXY Build | Thingiverse Profile

                      FelixHundefined 1 Reply Last reply Reply Quote 0
                      • FelixHundefined
                        FelixH @Phaedrux
                        last edited by

                        @Phaedrux yes it is consistent and also yes, it homes to the same spot.

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                        • fcwiltundefined
                          fcwilt @FelixH
                          last edited by

                          @FelixH said in Z trigger height:

                          I get, for example, a trigger height of 1.50mm. I set it on the config.g file and I do a test. The nozzle is way too far from the bed and I try to use Babystepping to get it closer. The Babystepping shows me a -0.15 (for example)... now what? Should I correct the config.g file and set the trigger height to 1.35 (1.5-0.15) ??

                          To get the nozzle to be closer to the bed you increase trigger height.

                          In your example you decreased it.

                          The trigger height determines how far the nozzle must move to reach Z=0. If the current value of the trigger height is leaving the nozzle above the bed then the nozzle did not move far enough. To get the nozzle to move more you increase the trigger height.

                          Frederick

                          Printers: a E3D MS/TC setup and a RatRig Hybrid. Using Duet 3 hardware running 3.4.6

                          FelixHundefined 1 Reply Last reply Reply Quote 1
                          • FelixHundefined
                            FelixH @fcwilt
                            last edited by

                            @fcwilt

                            To get the nozzle to be closer to the bed you increase trigger height.

                            In your example you decreased it.

                            This is exactly what puzzles me every time. The pop up on the Panel Due shows a minus value an yet, it’s the opposite...

                            fcwiltundefined 1 Reply Last reply Reply Quote 0
                            • fcwiltundefined
                              fcwilt @FelixH
                              last edited by

                              @FelixH said in Z trigger height:

                              This is exactly what puzzles me every time. The pop up on the Panel Due shows a minus value an yet, it’s the opposite...

                              I know it can be confusing.

                              When the probe is triggered the trigger height setting (assume 2 mm) says to the firmware "hey the nozzle is now 2mm above the bed". The firmware says to itself "ok so to move the nozzle to Z=0 I must move closer to the bed by 2mm"

                              When you adjust baby stepping to a negative value you are saying to the firmware "hey you need to move closer to the bed".

                              And as you can see to move closer to the bed requires a larger trigger height.

                              Frederick

                              Printers: a E3D MS/TC setup and a RatRig Hybrid. Using Duet 3 hardware running 3.4.6

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