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    skew correction

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    • Simoneundefined
      Simone
      last edited by

      i have done a first tes for the skew but i dont know if i did it right so i did another test with the precedet skew compensation activated Axis compensations - XY: -0.00146, YZ: -0.00305, ZX: -0.00146
      the second test is giving me this number Skew factor: 0.0014215
      Skew distance @ 99.4 mm: 5.981661 mm for XY

      What i need to do i change the XY: -0.00146 whit 0.0014215 or i need to add them? im more confident using the second test diagonal measurement |the first wase the one whit the ruler
      https://docs.duet3d.com/en/User_manual/Tuning/Orthogonal_axis_compensation

      OwenDundefined droftartsundefined 3 Replies Last reply Reply Quote 0
      • Phaedruxundefined Phaedrux marked this topic as a question
      • OwenDundefined
        OwenD @Simone
        last edited by OwenD

        @Simone
        I presume you're using the macro provided on the page indicated?

        It would be better if you specified the measurements you took for each value, perhaps with pictures.

        If the skew is indeed 5mm @ 100mm then you need to fix the hardware misalignment, not try to compensate with software.

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        • droftartsundefined
          droftarts administrators @Simone
          last edited by droftarts

          @Simone I updated the documentation a while ago to include the second method, and it was then pointed out that the skew calculation output the skew factor with the incorrect sign. See https://forum.duet3d.com/post/307701

          I was going to check it and update the documentation, but I forgot! But as @CalinFlorin86 pointed out, if the angle was acute (ie AC > BD) the skew factor should be negative, and if the angle was obtuse (ie AC < BD) the skew factor should be positive. I have updated the documentation to note this, and updated the macro so the output should be correct.

          That the numbers you are seeing are basically the same (XY: -0.00146 the first time, and Skew factor: 0.0014215 the second time, though this should be negative), it sounds like skew compensation was not active the second time. Otherwise the print would be square, I think.

          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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          • droftartsundefined
            droftarts administrators @Simone
            last edited by

            @Simone I've updated the calibration macro again, so this time it actually works correctly! @OwenD was kind enough to point out the error in my maths, which gave NaN results in some circumstances, and checked that it now gives correct answers. See https://docs.duet3d.com/en/User_manual/Tuning/Orthogonal_axis_compensation#calculate-the-skew-factor

            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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