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    High retraction length

    Tuning and tweaking
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    • loft
      loft last edited by

      First thank you in advanced for any advice , I have spent months due to my lack of knowledge in 3d printer building trying to get my dbot printer to work.

      It seems that I'm having to use a large number to get my prints to stop having blobs and zits in my print.

      Right now my retraction length is 13mm which is extremely high and acctually causes jams due to the filament retracting so far back.

      I assum this is from another cause but I'm not sure what? Is it stepper settings for extrusion ? If so can I make small adjustments to fix it without throwing everything out of wack?

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      • AS-3D Druck
        AS-3D Druck last edited by

        If you are a Bowden User than you can try this:

        Max Retract Length = TZ length + (BT length / 250mm)

        (On the e3D V6 Bowden TZ length is about 2.5mm - 3mm)

        This is what i found yesterday in the Prometheus Hotend Wiki:
        https://www.distechautomation.com/pages/pro-v2-hot-end-guide#1.03

        Best regards
        AS-3D Druck / Andre

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        • KeeganB
          KeeganB last edited by

          @AS-3D:

          If you are a Bowden User than you can try this:

          Max Retract Length = TZ length + (BT length / 250mm)

          (On the e3D V6 Bowden TZ length is about 2.5mm - 3mm)

          This is what i found yesterday in the Prometheus Hotend Wiki:
          https://www.distechautomation.com/pages/pro-v2-hot-end-guide#1.03

          Jumping in here, because that formula interested me. I did a quick calculation with it for my Rostock Max and that would put my retraction at 5mm, which seems pretty high to me.

          Artemis
          Rostock Max v2
          Orion

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          • deckingman
            deckingman last edited by

            Like all these things, it's just a rule of thumb and every extruder/hot end/filament/speed/temperature/pressure advance setting/stepper motor/voltage combination will be different IMO

            Ian
            https://somei3deas.wordpress.com/
            https://www.youtube.com/c/deckingman/

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            • dc42
              dc42 administrators last edited by

              My rule of thumb is that retraction length should be about 1mm plus a little less than 1% of the Bowden tube length. This is with 1.75mm filament in standard 2mm ID tubing.

              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

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              • AS-3D Druck
                AS-3D Druck last edited by

                @KeeganB:

                @AS-3D:

                If you are a Bowden User than you can try this:

                Max Retract Length = TZ length + (BT length / 250mm)

                (On the e3D V6 Bowden TZ length is about 2.5mm - 3mm)

                This is what i found yesterday in the Prometheus Hotend Wiki:
                https://www.distechautomation.com/pages/pro-v2-hot-end-guide#1.03

                Jumping in here, because that formula interested me. I did a quick calculation with it for my Rostock Max and that would put my retraction at 5mm, which seems pretty high to me.

                Btw this is from the Prometheus Wiki maybe this calculation works better with there System.

                Best regards
                AS-3D Druck / Andre

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                • KeeganB
                  KeeganB last edited by

                  @AS-3D:

                  @KeeganB:

                  @AS-3D:

                  If you are a Bowden User than you can try this:

                  Max Retract Length = TZ length + (BT length / 250mm)

                  (On the e3D V6 Bowden TZ length is about 2.5mm - 3mm)

                  This is what i found yesterday in the Prometheus Hotend Wiki:
                  https://www.distechautomation.com/pages/pro-v2-hot-end-guide#1.03

                  Jumping in here, because that formula interested me. I did a quick calculation with it for my Rostock Max and that would put my retraction at 5mm, which seems pretty high to me.

                  Btw this is from the Prometheus Wiki maybe this calculation works better with there System.

                  Yeah, I read through that link. Interesting stuff in there.

                  Doing David's method puts my "calculated" retraction at about 6mm, which is even longer! Those lengths, whether right or wrong, seem like they'd suck too much molten plastic into the cooling area.

                  Artemis
                  Rostock Max v2
                  Orion

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                  • fma
                    fma last edited by

                    That's why I recently switched to a Lite6, as I don't print high temperature filaments. With the Lite6, you can retract whatever value you want without jamming it.

                    Frédéric

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                    • loft
                      loft last edited by

                      Thanks guys! I so far have tried the calculation and it seems to have worked. Im still getting a little blobbing but Im tweaking the extra restart a little to see if that helps. The jamming has stopped as well.

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                      • deckingman
                        deckingman last edited by

                        @KeeganB:

                        …............................................................
                        Yeah, I read through that link. Interesting stuff in there.

                        Doing David's method puts my "calculated" retraction at about 6mm, which is even longer! Those lengths, whether right or wrong, seem like they'd suck too much molten plastic into the cooling area.

                        Not really. It's certainly a fact that longer Bowden tubes need more retraction. The theory behind that, is that the filament buckles and twists inside the Bowden tube and 1mm in 100mm seems to be a not unreasonable value. So if you have (say) a 400mm Bowden tube and retract 6mm, then 4mm will be to "straighten out" the filament inside the tube and only 2mm will actually be pulled back from the nozzle. If there is any "play" in the couplings then that too can add to the amount of retraction needed. Typically the standard type of pneumatic couplings that are often used can have a couple of mm play if you don't use clips under them, so that could add another 4mm to what is needed. So adding it all up, a 400, Bowden tube with "sloppy" couplings could need as much as 10mm retraction in order to pull 2mm from the nozzle.

                        Ian
                        https://somei3deas.wordpress.com/
                        https://www.youtube.com/c/deckingman/

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                        • DeltaCon
                          DeltaCon last edited by

                          @KeeganB:

                          Doing David's method puts my "calculated" retraction at about 6mm, which is even longer! Those lengths, whether right or wrong, seem like they'd suck too much molten plastic into the cooling area.

                          I think perhaps David meant "1% of the bowden lenghth measured in centimeter". Bowden lengths on Delta's are most often mentioned in cm. That would put the retraction length at 1.6mm which is fine for E3D and HE280 hotends.

                          If you think trial and error is dangerous, try routine. That's even more so!

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                          • KeeganB
                            KeeganB last edited by

                            @DeltaCon:

                            @KeeganB:

                            Doing David's method puts my "calculated" retraction at about 6mm, which is even longer! Those lengths, whether right or wrong, seem like they'd suck too much molten plastic into the cooling area.

                            I think perhaps David meant "1% of the bowden lenghth measured in centimeter". Bowden lengths on Delta's are most often mentioned in cm. That would put the retraction length at 1.6mm which is fine for E3D and HE280 hotends.

                            Maybe, as that number seems much more reasonable.

                            Artemis
                            Rostock Max v2
                            Orion

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                            • dc42
                              dc42 administrators last edited by

                              No, I meant 1% of the Bowden tube length. I use 4mm on my Ormerod (350mm Bowden tube) and before I enabled pressure advance I needed 7mm on my delta (60mm Bowden tube).

                              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

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