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    After tool change extruder absolute position is ignored

    Scheduled Pinned Locked Moved
    Duet Hardware and wiring
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    • opticalundefined
      optical
      last edited by optical

      I have a PNP machine with dual head.
      Board: Duet 3 MB6HC (MB6HC)
      Firmware: RepRapFirmware for Duet 3 MB6HC 3.1.1 (2020-05-19b2

      Axes description.
      X,Y - Standard axes.
      Z - Shared axis for both tools(head).
      E1,E2 - Axes configured to absolute positioning. Thes axes handles rotation of each head.

      Rotation axes has to be set to absolute position, because the openpnp is sending absolute rotation for the tools.
      Current setup uses tools which each is mapped to use single E axis. The reason for this is that i'm unable to define Tool with custom axis for remapping there is currently only support for X,Y. Therefore i had to use E selection.

      Issue:
      T0
      G0 180 ; Tool 0 moves to 180
      T1
      G0 180; Tool 1 moves to 180
      T0
      G0 180 ; Tool 0 moves to 360. This is the issue.
      Note that the machine is displaying that E0 is at 360 now. It is not that it resets the position, but it uses the current position as 0 for absolute movements.
      Could you tell me if it's desired behavior ?
      Configuration of axes:
      M82 ; absolute extruder moves
      M584 X0 Y1 Z2 E3:4 ; set drive mapping
      M350 X64 Y64 Z4 E32:32 I1 ; configure microstepping with interpolation
      ; Other direction current etc. are propably not needed

      Tool definitions:
      ; Define Tool 0
      M563 P0 D0
      ; Define Tool 1
      M563 P1 D1

      Whole configuration:
      config.g

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      • droftartsundefined
        droftarts administrators
        last edited by

        @optical I'd guess you have an M83 command (set extruder to relative mode) somewhere. Check the gcode and your tool change gcode files in the sys folder, eg tfree0.g, tpre0.g and tpost0.g. These run on tool change if they are present. For full explanation see https://duet3d.dozuki.com/Wiki/ConfiguringRepRapFirmwareCartesianPrinter#Section_Tool_change_files

        Ian

        Bed-slinger - Mini5+ WiFi/1LC | RRP Fisher v1 - D2 WiFi | Polargraph - D2 WiFi | TronXY X5S - 6HC/Roto | CNC router - 6HC | Tractus3D T1250 - D2 Eth

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        • opticalundefined
          optical
          last edited by optical

          I have searched the configuration and found M83 in scripts resume.g and pause.g.
          Can i ask you when these scripts are invoked ?
          I will try to erase it and came back to you. However, i'm worried that this is not the issue.

          The tool scripts are not present.

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          • opticalundefined
            optical
            last edited by optical

            I have remove the M83 gcodes from resume.g pause.g. These were not the issue. They were never called.

            I have performed these commands with following result:

            T0
            G0 E100 ; E0 - 100, E1 - 0
            T1
            G0 E0 ; E0 - 100, E1 - '-100' <- this is fault 
            G0 E0 ; E0 - 100, E1 - '-100' 
            G0 E0 ; E0 - 100, E1 - '-100' subsequent commands shows that the Extruder is indeed in absolute mode
            

            It looks like the absolute position of the E axis is retain between the tools. (i dont know why it is inversed)

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            • dc42undefined
              dc42 administrators
              last edited by

              Extruders are inherently relative. Don't use them where you need absolute positioning; create additional axes using M584 instead.

              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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              • opticalundefined
                optical
                last edited by optical

                I would like to do that however how can i configure tool mapping for this new axes ?

                https://duet3d.dozuki.com/Wiki/Gcode#Section_M563_Define_or_remove_a_tool

                Shows only X,Y axes are supported for the remapping ?

                If you cannot use extrudes in absolute manor why then support M82 ?

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                • dc42undefined
                  dc42 administrators
                  last edited by dc42

                  Are you saying that you need to use the same G1 xnnn command for some axis designator x, no matter which tool is selected? And that you need each tool to remember the position of that axis, independently of the other tool?

                  Are you using OpenPNP?

                  Does this axis represent rotation of the PnP head?

                  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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                  • opticalundefined
                    optical
                    last edited by optical

                    Yes that is the use case.

                    Yes i'm using OpenPNP. Inside open pnpn i have defined 2 nozzles. Each have premove command set to "T0" or "T1". I have digged pretty deep inside the documentation and this is the prefered way. I haven't found a way how to define 2 rotation axis inside openpnp.
                    This is preferd way according openpnp documentation

                    Yes this axis represent rotation of the PnP Head.
                    currently i'm, using this type of head

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                    • opticalundefined
                      optical
                      last edited by

                      Hi.
                      I have tried 3.2beta2 and 3.2beta1 issue present in both of the versions.

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