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    How to calibrate the extruder

    Tuning and tweaking
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    • Brmatt
      Brmatt last edited by

      I have found that my extruder is WAY over extruding. It pushed out a little over 14 inches of filament when instructed to push out 50mm. Seems its over extruding about 7 times too much. I believe this is the parameter I need to change however I am unsure about the formatting of it. Is it a set up as E(steps):(mm)?
      0_1543614907324_253776ec-4df0-42d6-9f0a-13dce10f0bcd-image.png

      Stephen6309 Phaedrux 2 Replies Last reply Reply Quote 0
      • Stephen6309
        Stephen6309 @Brmatt last edited by Stephen6309

        @brmatt The extruder is calibrated for the amount of filament going into the hotend.

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        • Brmatt
          Brmatt last edited by

          And? Sorry I don't follow what you are saying

          Stephen6309 1 Reply Last reply Reply Quote 0
          • Brmatt
            Brmatt last edited by

            For reference I am using a bowden tube set up and while testing this I was not feeding into the hotend, just out if the end of the open tube. I told it to extrude 50mm at 5mm/sec. Instead it extruded around 350mm.

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            • aidar
              aidar last edited by

              Have you ever read documentation? specially section https://duet3d.dozuki.com/Wiki/Step_by_step_guide#Section_Initial_configuration

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              • Stephen6309
                Stephen6309 @Brmatt last edited by

                @brmatt You calibrate for how much filament fed into the extruder, you don't use what's coming out of the nozzle.

                Phaedrux Brmatt 2 Replies Last reply Reply Quote 0
                • Phaedrux
                  Phaedrux Moderator @Stephen6309 last edited by

                  @stephen6309 I dont think he has the nozzle on, so as long as you're measuring from the right points it's a totally valid way to measure e steps.

                  Z-Bot CoreXY Build | Thingiverse Profile

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                  • Phaedrux
                    Phaedrux Moderator @Brmatt last edited by Phaedrux

                    @brmatt M92 E###:### refers to two seperate extruders. If you only have one extruder, you can remove the colon and second value.

                    The number itself refers to the steps needed for the motor to move 1 mm.

                    I just noticed that the guide in the Duet documentation is not yet written (I should fix that) but here's another guide that gives a good overview on the general procedure.

                    https://mattshub.com/2017/04/19/extruder-calibration/

                    It's specific to Marlin, but the math is the same.

                    You can use this formula if you have a known gear ratio extruder to get you close to the ideal steps per mm.
                    e_steps_per_mm = (motor_steps_per_rev * driver_microstep) * (big_gear_teeth / small_gear_teeth) / (hob_effective_diameter * pi)

                    Then you can use the actual extrusion measurement to fine tune it with this formula.

                    New e steps = old_e_steps * (100 / (110 - distance_to_mark))
                    M83; to set relative extrusion
                    Make a mark on filament 110mm from the top of extruder
                    G1 E100 F100; extrude 100mm at slow speed
                    Measure distance from top of extruder to mark.
                    If it went below, estimate how many mm it went down, and enter a negative number.

                    The longer you extrude, the more accurate your final result would be. 100mm is a good start. You may need to repeat the process a few times.

                    Z-Bot CoreXY Build | Thingiverse Profile

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                    • dc42
                      dc42 administrators last edited by

                      If an E steps/mm of 663 is about 7 times too much, then I guess you are using an un-geared extruder. Is that correct? Those usually have around 100 steps/mm.

                      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

                      Brmatt 1 Reply Last reply Reply Quote 0
                      • Brmatt
                        Brmatt @Stephen6309 last edited by

                        @stephen6309 as Phaedrux said I don't have the nozzle on that's what I meant when I said "not feeding into the hotend, just out if the end of the open tube"

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                        • Brmatt
                          Brmatt @dc42 last edited by

                          @dc42 That is correct it is un-geared. Thanks for the advice. Ill start messing around with the number.

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