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    Using a measured z/steps value vs calculated

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    • Phaedruxundefined
      Phaedrux Moderator
      last edited by

      I'd probably print a larger object than just a small cube to make sure the measured steps are accurate over a larger range.

      Z-Bot CoreXY Build | Thingiverse Profile

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      • Turboundefined
        Turbo @Phaedrux
        last edited by

        @Phaedrux will be back when 100mm tall cube print is done

        Cant stop tuning wont stop tuning.
        Dbot, Custom i3, Voron 0&2

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        • Turboundefined
          Turbo @Phaedrux
          last edited by Turbo

          @Phaedrux 100mm tall print (changed to 99.9 due to 0.3 layer height) shows up as 99.6mm. Still 0.3mm off but only slightly. if it was a steps thing wouldn't it be a greater inaccuracy due to the increase in height?

          Cant stop tuning wont stop tuning.
          Dbot, Custom i3, Voron 0&2

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          • A Former User?
            A Former User
            last edited by A Former User

            How thick is a single layer? (as printed)

            Turboundefined 1 Reply Last reply Reply Quote 0
            • Turboundefined
              Turbo @A Former User
              last edited by

              @bearer 0.2 mm when requesting 0.2mm. this is before adding a scaling modifier to the z axis.

              Cant stop tuning wont stop tuning.
              Dbot, Custom i3, Voron 0&2

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              • nhofundefined
                nhof
                last edited by nhof

                You should expect step/mm error to be proportional to the print height. If you're getting the same overall error regardless of the print size it's likely due to something else.

                Could be backlash or something mechanical, particularly if the first layer Z plane was approached from the opposite direction of subsequent layers. Most cheap stepper gearboxes have quite a bit of backlash, usually they're quoted at 1.5 to 3 degrees, which would be up to .33mm with a 20t 2mm pulley (40mm/rev).

                Steps/mm numbers look correct, my calc gives out 414.545455 steps/mm. Assuming 200 steps/mm motor, 20t drive gear, 5 2/11 gearbox, 2mm belt pitch.

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                • arhiundefined
                  arhi @Turbo
                  last edited by

                  @Turbo said in Using a measured e/steps value vs calculated:

                  @arhi i know what youre saying but that doesnt answer my question. If the calculated z steps is giving me an inaccurate dimension, is something else wrong or is it just hardware deficiency?

                  Well the topic you created is e/steps and then you are talking about Z/steps so it's not really clear what you are asking.

                  I personally never measure "part" to determine machine properties. Plastic is hard to measure and can lead you astray in many ways. Attach an indicator or caliper to the head, move head known value, read actual moved value from the caliper - compare.

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                  • Turboundefined
                    Turbo @arhi
                    last edited by Turbo

                    @arhi my bad, so used to seeing the term e steps and not z steps. fixed in title.
                    ill try that method shortly. although having part dimensional accuracy is the point, and while i get measuring the printers accuracy like you're saying, it really wouldn't help me if the printer is accurate to 20.00mm for example, but the prints are coming out a different size.

                    Cant stop tuning wont stop tuning.
                    Dbot, Custom i3, Voron 0&2

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                    • arhiundefined
                      arhi @Turbo
                      last edited by

                      @Turbo said in Using a measured e/steps value vs calculated:

                      @arhi my bad, so used to seeing the term e steps and not z steps. fixed in title.
                      ill try that method shortly. although having part dimensional accuracy is the point, and while i get measuring the printers accuracy like you're saying, it really wouldn't help me if the printer is accurate to 20.00mm for example, but the prints are coming out a different size.

                      more than one thing is influencing part dimensions... you start with making your printer move "properly", ignore part size, make sure you printer move the way it supposed to. then if parts are wrong size find out why (extruder calibration, slicer calibration, shitty slicer, bad print surface, butterflies... ) ... but you can't start to fix other issues unless you are sure your printer movements are accurate..

                      also if your cube is wrong .1mm on 10mm, is it wrong again .1mm on 100mm or is now 1mm wrong? FDM is not a super precise process, .1mm is not a big issue, 1% is a big issue

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                      • Turboundefined
                        Turbo
                        last edited by

                        @arhi You were right with regards to the printer not moving "properly". So, after switching to linear rails on the z axis, I found my z axis dimensions to be spot on with the calculated value. I believe there may have been some unwanted friction using the v-rollers, causing the prints to come slightly short.

                        Cant stop tuning wont stop tuning.
                        Dbot, Custom i3, Voron 0&2

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