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    XY size compensation

    Tuning and tweaking
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    • fma
      fma last edited by

      Hi!

      I'm doing some tests with Slic3r 'XY size compensation param'.

      I printed a test part, with different holes sizes, and measured them: I have a constant offset, but it is different along X and Y!!! I should increase X by 0.2mm, but Y by only 0.1mm… But Slic3r only has 1 global value.

      Any idea what can cause that?

      BTW, it is the same for external values: I got 71.8mm for 72mm along X, and 41.9mm for 42mm along Y...

      Thanks,

      Frédéric

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      • dc42
        dc42 administrators last edited by

        What type of printer do you have?

        See also https://duet3d.com/wiki/G-code#M579:_Scale_Cartesian_axes.

        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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        • fma
          fma last edited by

          It's a CoreXY.

          I can't use a scale factor, as it is really an offset. Same on a 5mm hole as on external 72x42mm rectangle (0.2/0.1mm)…

          I don't think it is a XY motor problem, but more an extrusion issue. But I can't see how it can be. Unless the nozzle hole is not circular?

          Frédéric

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          • dc42
            dc42 administrators last edited by

            If it's an offset rather than a scale factor, it is caused by backlash?

            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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            • fma
              fma last edited by

              I noticed that my rectangular test part, with all the holes, was not orthogonal. Which could explain why the holes are not circular.

              So, I printed another test part, made of a 100x100mm set square, in order to measure and correct this: it is perfect!!!

              I'm puzzled…

              Frédéric

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              • fma
                fma last edited by

                Sorry, I missed your post.

                I don't see any backlash in the carriage; belts are well tensioned. But I will check the hotend mount.

                Frédéric

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                • fma
                  fma last edited by

                  Ok, the problem of non orthogonality appears when the part cools down; there are big holes on one side, small ones on the other side, so PLA retracts and twists the part. That's probably why my holes are not circular.

                  I will make another bigger print test part to check.

                  Frédéric

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                  • DjDemonD
                    DjDemonD last edited by

                    Hi fma, one test for orthogonality which is quite robust with corexy is to print 5 squares, hollow only 2 layers tall, and maybe 2mm thick. Print one at each corner of the bed, and one in the centre. When they cool take them off and make sure they are all square and sit on top of one another perfectly. This test will show up slightly off square belt paths which exaggerate the effect in the corners rather than the centre.

                    Simon. Precision Piezo Z-Probe Technology
                    www.precisionpiezo.co.uk
                    PT1000 cartridge sensors NOW IN, just attach to your Duet board directly!

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                    • fma
                      fma last edited by

                      Thanks for the advice. But I'm not sure to see how the squares should look like; do you have an example, on Thingiverse, for example?

                      Frédéric

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                      • DjDemonD
                        DjDemonD last edited by

                        Not on Thingiverse but this stl should show you what i mean:

                        https://1drv.ms/u/s!Apv79JfGbPIwg4EvUgYnxrRgAAxV5g

                        Each one has a unique notch, so once you take them off the printer you can work out which was which.

                        If the centre one is a parallelogram then the x and y axes are not orthogonal (belt tension unequal) if any of the corner squares are not square then the belt paths are not precisely 90 degrees from the x carriage to y carriages and y carriages to motors/pulleys.

                        Simon. Precision Piezo Z-Probe Technology
                        www.precisionpiezo.co.uk
                        PT1000 cartridge sensors NOW IN, just attach to your Duet board directly!

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                        • fma
                          fma last edited by

                          Thanks!

                          Frédéric

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