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    Clearpath Servos with 1XD Expansion

    Scheduled Pinned Locked Moved Unsolved
    Duet Hardware and wiring
    clearpath expansion 1xd duet 3 servo
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    • jballard86undefined
      jballard86 @JoergS5
      last edited by

      @JoergS5 20200726_135227.jpg

      Here is one example, the shifts are sporadic in direction, they can be along axis lines, and then diagonally.

      A real simple shape such as a cube has no issues, but if you add any features it becomes problematic.

      1 Reply Last reply Reply Quote 0
      • jballard86undefined
        jballard86 @JoergS5
        last edited by

        @JoergS5 ill mark the pulleys and retest.

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        • jballard86undefined
          jballard86 @JoergS5
          last edited by

          @JoergS5 I milled shallow flats in my servo shafts, they are still lined up with the set screws, however I marked them just in case.

          Ran file, marks still line up.

          JoergS5undefined 1 Reply Last reply Reply Quote 0
          • JoergS5undefined
            JoergS5 @jballard86
            last edited by JoergS5

            @jballard86 your layer shifts look interesting...

            One remarkable detail is that the shift is of the kind if it shifts, left and right shift to the same direction. So the shift is not due to a lower print distance.

            One reason for layer shifts are print bed shifts, but when you get less shifts with lower speed, so this is unprobable. Can you exclude this possibility? (how good is your Z movement system?)

            The next possible reason is that the nozzle touches the object while layer change and moves it. There is something called Z-hop in the slicer to take the nozzle away.

            One possible reason, not probably not in your case but I want to mention it, is that something is in the way for the actuators, like cables, which disturb the movement.

            One intersting detail in your image is that there are multiple layers shifting into one direction, then multiple layers shifting into the other direction, but different number of shifts for every direction. There must be a reason for this. If we found the reason, we know the solution!

            It would be interesting to make a test at layer change, whether the coordinates are still correct, but testing the values at the endstops.

            jballard86undefined 1 Reply Last reply Reply Quote 0
            • jballard86undefined
              jballard86
              last edited by

              Z axis is remarkably stiff, z rails, kinematic mounts, all aluminum, mounted to 1"x2: aluminum bar for increased rigidity.

              Never had good luck with zhop in the 10+ years ive used 3d printers. so Zhop is disabled.

              Nothing is disturbing movement, besides the clearpath software would give me an error if there was an over torque situation, which would indicate that there was a collision of some sort in this type of scenario.

              but you are right, the shifts are interesting. Ive taken everything out of the question that is unnecessary for a print to print (albeit ugly), Ive verified that the servos are not missing steps, ive modified accelerations, jerks, speeds, etc with no change.

              I know that for some reason there is a pause on the 1XD boards when there is a layer change where the servos actually go into an idle mode.

              ive deactivated the bed heater (110v) encase it is causing interference, ive checked that all cables are not ran next to a cable that would cause issues with interference.

              This problem is firmware, hardware, or interference related.

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              • jballard86undefined
                jballard86 @JoergS5
                last edited by

                @JoergS5 1595788369262748058825589497704.jpg 15957884262876700327851583911019.jpg

                JoergS5undefined 1 Reply Last reply Reply Quote 0
                • jballard86undefined
                  jballard86 @JoergS5
                  last edited by

                  @JoergS5

                  I have tested after a series of layer shifts:

                  After Homing
                  Duet (0,0)
                  Servos ( 3574, -426)

                  After a few layer shifts
                  Duet (0,0)
                  Servos (3500, -417)

                  The servos know where they are and the Duet thinks it knows where it is, but it has had something happen in communication or elsewhere that causes it to loose its actual location (im thinking it has to do with the 1XD boards)

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                  • JoergS5undefined
                    JoergS5 @jballard86
                    last edited by JoergS5

                    @jballard86 I have thought about why the direction of the layer shifts is different. Maybe it is because the fast movement to the begin of the new layer is from left to right or right to left. Did you check that the steps/mm are all correct? And if layer changes, is there something special in the G-Code like using G0 instead of G1, different speeds or something other special?

                    You can insert a macro at layer change to verify if the coordinate system is still correct, testing the positions at the endstops. There is a thread somewhere in the forum to test endstop at every layer.

                    => our posts crossed again 😉 Our thoughts are in the same direction, that the coordinates change at the layers.

                    jballard86undefined 3 Replies Last reply Reply Quote 0
                    • jballard86undefined
                      jballard86 @JoergS5
                      last edited by

                      @JoergS5
                      Its a core xy setting steps/mm is irrelevant, you use the Mcode to scale the x and y

                      Testing at later change could give some interesting results but I'm using hard stops, so not viable if the shifts are in the wrong direction. And as I can't log both servos count position at the same time and have to swap cables it could take an afternoon or longer to run and rerun tests.

                      Do you think the servos are loosing position or the duet? Im 100% confidant that it's the duet as I've already shown that.

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                      • jballard86undefined
                        jballard86 @JoergS5
                        last edited by

                        @JoergS5 Post crossing is happening often 😅

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                        • jballard86undefined
                          jballard86 @JoergS5
                          last edited by

                          @JoergS5 I'm adding a g4 s.5 on layer change, I predict it may stop the shift, but is also not an acceptable solution. Results in a few min.

                          JoergS5undefined 1 Reply Last reply Reply Quote 0
                          • JoergS5undefined
                            JoergS5 @jballard86
                            last edited by

                            @jballard86 M400 before layer change would be a test also. Maybe XY throws a movement away when Z move starts.

                            jballard86undefined 2 Replies Last reply Reply Quote 0
                            • jballard86undefined
                              jballard86 @JoergS5
                              last edited by

                              @JoergS5

                              g4 reduced a lot of the shifts, trying:

                              m400
                              g4 s.5

                              results in a few

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                              • jballard86undefined
                                jballard86 @JoergS5
                                last edited by

                                @JoergS5
                                still shifting with m400 and g4 s.5

                                JoergS5undefined 1 Reply Last reply Reply Quote 0
                                • JoergS5undefined
                                  JoergS5 @jballard86
                                  last edited by

                                  @jballard86 at the moment I don't have additional ideas. I will think about and tell you when I have a new one.

                                  jballard86undefined 1 Reply Last reply Reply Quote 0
                                  • jballard86undefined
                                    jballard86 @JoergS5
                                    last edited by

                                    @JoergS5 15957904407291965536359268878336.jpg

                                    This is interesting, it had shifts mid layer on the skirt

                                    I'm out of ideas as well, maybe @dc42 can give some more input.

                                    JoergS5undefined 1 Reply Last reply Reply Quote 0
                                    • JoergS5undefined
                                      JoergS5 @jballard86
                                      last edited by JoergS5

                                      @jballard86 slip through of the belt to the pulley is a possibiltiy also, but you would hear it. But I don't know how to verify it.

                                      jballard86undefined 1 Reply Last reply Reply Quote 0
                                      • jballard86undefined
                                        jballard86 @JoergS5
                                        last edited by

                                        @JoergS5 an I am unfortunately aware of that noise from when I was setting up hard stop homing

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                                        • tae wimjuundefined
                                          tae wimju
                                          last edited by

                                          Hi. This may be long-shot, but...have you check that all ClearPath motor has the exact same RAS setting, and that the motor are not set to "Auto RAS"? Keep the RAS setting fairly low, like no more then 25mS (mine only let me set maximum 16mS which work OK fine for me. But make sure the RAS values match exactly the same. Good luck with print machine!

                                          jballard86undefined 1 Reply Last reply Reply Quote 0
                                          • NitroFreakundefined
                                            NitroFreak
                                            last edited by

                                            I had the same exact problems on my JMC servo,
                                            I guess you are not using the duet expansion breakout board? That fixes it.
                                            You need the 5V logic for the steps to arrive properly, the 3.3v logic from the mainboard is enough to trigger some steps to run normally but not all of them.

                                            So yes you need the expansion breakout board. here is my thread on it
                                            https://forum.duet3d.com/topic/8948/3-3v-logic-for-5v-servomotor-optocouplers

                                            1 Reply Last reply Reply Quote 1
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