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    CoreXY - X-Axis Vibration Issues

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    • zaptaundefined
      zapta @Veti
      last edited by zapta

      @veti said in CoreXY - X-Axis Vibration Issues:

      i think this is why BLV uses 16 tooth pulleys and 0.9 Steppers on his cube.

      I just install same 0.9 stepper as the (x-y) motor of my printer and the vibrations of the (x-y) diagonal movements test are gone! I have another one on order for the (x+y) motor. It seems that 0.9deg steppers do make a difference.

      https://www.amazon.com/gp/product/B00W9A2L3S

      fcwiltundefined Vetiundefined 2 Replies Last reply Reply Quote 0
      • fcwiltundefined
        fcwilt @zapta
        last edited by

        @zapta said in CoreXY - X-Axis Vibration Issues:

        I just install same 0.9 stepper as the (x-y) motor of my printer and the vibrations of the (x-y) diagonal movements test are gone! I have another one on order for the (x+y) motor. It seems that 0.9deg steppers do make a difference.

        https://www.amazon.com/gp/product/B00W9A2L3S

        Was your printer already setup with a 24 volt power supply?

        Thanks.

        Frederick

        Printers: a small Utilmaker style, a small CoreXY and a E3D MS/TC setup. Various hotends. Using Duet 3 hardware running 3.4.6

        zaptaundefined 1 Reply Last reply Reply Quote 0
        • zaptaundefined
          zapta @fcwilt
          last edited by

          Was your printer already setup with a 24 volt power supply?

          Yes, all parts are on 24V, including heaters and fans, no buck converters and such. The only add-on is this SSR to reduce heat on the Duet https://www.auberins.com/index.php?main_page=product_info&products_id=288

          fcwiltundefined 1 Reply Last reply Reply Quote 0
          • fcwiltundefined
            fcwilt @zapta
            last edited by

            @zapta said in CoreXY - X-Axis Vibration Issues:

            Was your printer already setup with a 24 volt power supply?

            Yes, all parts are on 24V, including heaters and fans, no buck converters and such. The only add-on is this SSR to reduce heat on the Duet https://www.auberins.com/index.php?main_page=product_info&products_id=288

            And I just finished tidying up the wiring on my 12 volt setup making the conversion a bit more work. Sigh...

            So, let's see, I need new heaters, new fans, new steppers and a new bulb for my illuminated emergency stop button...

            Thanks for the info.

            Frederick

            Printers: a small Utilmaker style, a small CoreXY and a E3D MS/TC setup. Various hotends. Using Duet 3 hardware running 3.4.6

            zaptaundefined 1 Reply Last reply Reply Quote 0
            • Vetiundefined
              Veti @zapta
              last edited by Veti

              @zapta said in CoreXY - X-Axis Vibration Issues:

              I just install same 0.9 stepper as the (x-y) motor of my printer and the vibrations of the (x-y) diagonal movements test are gone! I have another one on order for the (x+y) motor. It seems that 0.9deg steppers do make a difference.

              Same for me. But can anyone give an explanation as to why this solves the problem?
              My current theory is that the microstepping can not hold the inbetween steps in all cases.
              i.e at some steps closer to the full step the holding force is not great enough which causes the driver to move/remain at the full step resolution. causing more filament to be extruded at the full step position.

              edit: found this https://www.machinedesign.com/archive/microstepping-myths

              zaptaundefined 1 Reply Last reply Reply Quote 1
              • zaptaundefined
                zapta @fcwilt
                last edited by

                @fcwilt said in CoreXY - X-Axis Vibration Issues:

                And I just finished tidying up the wiring on my 12 volt setup making the conversion a bit more work. Sigh...

                And I just tied up my wiring, which resulted in the SSR giving up smoke and dying. Apparently I connected the control input in reverse polarity. 😉

                This was an opportunity to look inside the SSR. It's built like a tank and the power Mosfet has a large chunk of silicon in it.

                Connected the 12A/24V bed to the Duet directly and everything works like champ. Not sure if I want to install a new SSR. I like the current simplicity.

                dc42undefined fcwiltundefined 2 Replies Last reply Reply Quote 0
                • zaptaundefined
                  zapta @Veti
                  last edited by

                  @veti said in CoreXY - X-Axis Vibration Issues:

                  Same for me. But can anyone give an explanation as to why this solves the problem?
                  My current theory is that the microstepping can not hold the inbetween steps in all cases.

                  I think that my experiment of having vibration in a single stepper diagonal move (I as actually holding the other belt with my finger to make sure that there are no vibrations from the stationary motor) supports that this is not necessarily a result of an interaction between the two motors.

                  Your explanation sounds reasonable to me. Microstepping and Interpolation have their limits, especially that it is a modulation of the underlying PWM and not direct linear current source.

                  Another potential factor is that the 0.9 steppers are also larger (for same torque) and thus have higher mass and smoother rotation (?)

                  1 Reply Last reply Reply Quote 0
                  • Vetiundefined
                    Veti
                    last edited by Veti

                    i found this very good analysis of microstepping https://hackaday.com/2016/08/29/how-accurate-is-microstepping-really/

                    1 Reply Last reply Reply Quote 0
                    • dc42undefined
                      dc42 administrators @zapta
                      last edited by

                      @zapta said in CoreXY - X-Axis Vibration Issues:

                      Connected the 12A/24V bed to the Duet directly and everything works like champ. Not sure if I want to install a new SSR. I like the current simplicity.

                      12A is well within the rating of the Duet. I recommend that at regular intervals you check that the screws in the VIN and bed heater terminal blocks of the Duet are still tight, until you are sure that they are staying tight. This is because high currents can cause creep in wires. Crimping the correct ferrules on to the wire ends reduces this risk.

                      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

                      zaptaundefined 1 Reply Last reply Reply Quote 0
                      • fcwiltundefined
                        fcwilt @zapta
                        last edited by

                        @zapta said in CoreXY - X-Axis Vibration Issues:

                        Connected the 12A/24V bed to the Duet directly and everything works like champ. Not sure if I want to install a new SSR. I like the current simplicity.

                        My heaters are all line voltage heaters (110 VAC) and thus an SSR is needed.

                        Frederick

                        Printers: a small Utilmaker style, a small CoreXY and a E3D MS/TC setup. Various hotends. Using Duet 3 hardware running 3.4.6

                        1 Reply Last reply Reply Quote 0
                        • zaptaundefined
                          zapta @dc42
                          last edited by

                          @dc42 said in CoreXY - X-Axis Vibration Issues:

                          12A is well within the rating of the Duet.

                          Yes, it seems to handle it very well and the mosfet is cool even at 100% PWM (looked at it with an IR camera).

                          I did crimp cheap Chinese ferrules, hope they are right, they seem to be made of aluminum(?). Not sure how it will behave when oxidized. I know very little about it

                          dc42undefined 1 Reply Last reply Reply Quote 0
                          • dc42undefined
                            dc42 administrators @zapta
                            last edited by

                            @zapta said in CoreXY - X-Axis Vibration Issues:

                            Yes, it seems to handle it very well and the mosfet is cool even at 100% PWM (looked at it with an IR camera).

                            The rated bed heater current of the Duet isn't set by the MOSFET, it's determined by heating of the PCB traces. Even when using 2oz copper instead of the usual 1oz, and duplicating traces on both sides of the PCB, it's hard to carry 20A on a PCB.

                            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

                            1 Reply Last reply Reply Quote 0
                            • zaptaundefined
                              zapta
                              last edited by

                              @dc42, I presume you are aware of this technique but just in case

                              http://www.eevblog.com/forum/blog/eevblog-317-pcb-tinning-myth-busting/

                              dc42undefined 1 Reply Last reply Reply Quote 0
                              • Vetiundefined
                                Veti
                                last edited by

                                we have a name. VFA (Vertical Fine Artifacts)

                                https://shop.prusa3d.com/forum/user-mods-octoprint-enclosures-nozzles--f65/stepper-motor-upgrades-to-eliminate-vfa-s-vertical-t28098.html

                                it seems if you make your printer more precise these artefacts start to show.

                                after getting an ender 3 to play with i found these artefacts as well on the ender 3.
                                funny thing is the user started seeing the problem around the same time.

                                1 Reply Last reply Reply Quote 1
                                • dc42undefined
                                  dc42 administrators @zapta
                                  last edited by

                                  @zapta said in CoreXY - X-Axis Vibration Issues:

                                  @dc42, I presume you are aware of this technique but just in case

                                  http://www.eevblog.com/forum/blog/eevblog-317-pcb-tinning-myth-busting/

                                  Yes, but it's not very effective, especially if you are already using 2oz copper.

                                  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

                                  zaptaundefined 1 Reply Last reply Reply Quote 0
                                  • zaptaundefined
                                    zapta @dc42
                                    last edited by

                                    @dc42, yes, this is a good point. Doubling the copper thickness doesn't double the solder.

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