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    Getting both stringing and underextrusion

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    • Turboundefined
      Turbo
      last edited by Turbo

      I cant seem to figure out what would cause such a thing, as it's generally one or the other. After failing many retraction tests, I figured I'd try a benchy to see if anything had changed. Now not only am I getting underextrusion, but I'm also getting stringing, as if theres not enough retraction. When I increase retraction, the underextrusion gets much worse and the same goes for decreasing retraction and stringing.

      About the printer:
      D-Bot Corexy Printer with an E3D Chimera hotend. Bowden setup with 600mm Capricorn tubing and titan extruders, all genuine.
      this was printed with a .4 nozzle with Esun PLA+ at 210c (not a filament issue, works well on any other printer)

      PrusaSlicer Settings

      • Maxed out cooling
      • 2mm of retraction, although same results down to 1.3mm
      • 40mm/s retraction speed, although increasing the speed hasn't helped.
      • 60mm/s Print speed, pretty reasonable for the printer under normal circumstances
      • No pressure advance at the moment, as I was tuning extrusion shortly before this benchy.

      It seems like its retracting more than its de retracting, but I'm new to bowden so I'm not sure if I'm missing something blatantly obvious.

      Any more needed info I can hopefully supply.
      Thanks

      Ex. Benchy:
      MVIMG_20200327_123214.jpg

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

      Phaedruxundefined 1 Reply Last reply Reply Quote 0
      • Phaedruxundefined
        Phaedrux Moderator @Turbo
        last edited by

        @Turbo said in Getting both stringing and underextrusion:

        It seems like its retracting more than its de retracting, but I'm new to bowden so I'm not sure if I'm missing something blatantly obvious.

        check for loose couplings

        Z-Bot CoreXY Build | Thingiverse Profile

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        • Turboundefined
          Turbo
          last edited by Turbo

          @Phaedrux
          checked. all tight with the little spacer to keep them in place

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

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          • Phaedruxundefined
            Phaedrux Moderator
            last edited by

            How bout temperatures? Are you using an E3D thermistor? Do you have the correct values for it? Have you PID tuned? Have you done a temp tower? Have you tried a different filament?

            Next I'd try doing a rebuilt of the Chimera.

            Z-Bot CoreXY Build | Thingiverse Profile

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            • Turboundefined
              Turbo
              last edited by

              210c with a PID tune with a genuine e3d thermistor. never strays more than .1c.
              Id do a temp tower but i know this filament is good with my other printer, which uses the same pid tune and thermistor, but is direct drive.
              I have rebuilt it 3 times now in search of the problem. nothing painfully obvious

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

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              • Phaedruxundefined
                Phaedrux Moderator
                last edited by

                Pinch roller tension adjustment on the titan?
                Extruder motor current at 85% of rated motor max?
                Extruder calibrated?
                Retraction seems like it's in an ok starting point. so try tuning pressure advance now.

                Z-Bot CoreXY Build | Thingiverse Profile

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                • Turboundefined
                  Turbo
                  last edited by

                  Yep yep and yeah. I'll try tuning PA again, but last time it went up to about .7. Is that a familiar value with bowden?

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

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                  • Phaedruxundefined
                    Phaedrux Moderator
                    last edited by

                    that's not out of reason for long Bowden's. Definitely re read the pressure advance documentation. It's been updated recently.

                    Z-Bot CoreXY Build | Thingiverse Profile

                    Turboundefined 1 Reply Last reply Reply Quote 0
                    • Turboundefined
                      Turbo @Phaedrux
                      last edited by

                      @Phaedrux Pressure advance was right around .75-.8 for best results. however, this did not fix any stringing/underextrusion
                      I took off the nozzle to check that it wasnt doing more retraction than extrusion, and its perfect. Im at a loss here

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

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                      • Phaedruxundefined
                        Phaedrux Moderator
                        last edited by

                        worn out nozzle?

                        Z-Bot CoreXY Build | Thingiverse Profile

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                        • Turboundefined
                          Turbo
                          last edited by

                          SOLVED

                          For some reason, a medium retraction distance and slow retraction speed works best.
                          I found 2.4-2.8mm of retraction at 20-25mm/s retraction speed to work best.
                          I have no idea why the Chimera hotend is like this, and it pretty much goes against what everything on the internet says, even E3D's recommendations, but it works!

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

                          Phaedruxundefined 1 Reply Last reply Reply Quote 0
                          • Phaedruxundefined
                            Phaedrux Moderator @Turbo
                            last edited by

                            @Turbo said in Getting both stringing and underextrusion:

                            it pretty much goes against what everything on the internet says

                            It's not crazy if it works!

                            Z-Bot CoreXY Build | Thingiverse Profile

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