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    Direct drive extruder and Bowden extruder on one machine?

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    bondtech tool e3d toolchanger extruder
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    • theruttmeisterundefined
      theruttmeister @engikeneer
      last edited by

      @engikeneer

      You could argue the Palette falls into this category.

      And in fact you can use the Palette to load filament into the head. But they have encoders and switches to make sure everything stays in sync.
      Palette splices though, because un-loading and loading filament is slow, wasteful and failure prone.

      Isolate, substitute, verify.

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

        @theruttmeister said in Direct drive extruder and Bowden extruder on one machine?:

        But they have encoders and switches to make sure everything stays in sync.

        😂

        Thanks for the laugh, I needed that.

        Z-Bot CoreXY Build | Thingiverse Profile

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        • theruttmeisterundefined
          theruttmeister
          last edited by

          You've lost me?

          Isolate, substitute, verify.

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

            @theruttmeister Sorry, I thought everyone was aware how notorious the Palette is for getting out of sync with splices taking too long and the buffer running out and there being no sensor to detect this and then snapping the filament.

            wasteful and failure prone.

            That part is bang on though.

            Z-Bot CoreXY Build | Thingiverse Profile

            theruttmeisterundefined 1 Reply Last reply Reply Quote 0
            • theruttmeisterundefined
              theruttmeister @Phaedrux
              last edited by

              @Phaedrux
              Clearly we have had very different experiences of the Palette... I've build multi-input heads, and I've used multiple generations of the Palette.
              The development units had some issues. But I have found the production units to be reliable. I'd certainly pick one over any multi-input design I've ever seen.

              Isolate, substitute, verify.

              1 Reply Last reply Reply Quote 0
              • aprzundefined
                aprz
                last edited by

                Very interesting points. I’ve heard of the mmu from Prusa it looks good and is less than the pallete but I’m not sure the mmu is worth buying at $299. The printer I have has a long Bowden tube and it takes while to push filament through and wanted to know if a single extruder at the other end of the bowden tube would be of any improvement besides loading quickly(already using a direct drive), considering that there’s articles on Bowden vs direct drive extrusion just came to mind.

                deckingmanundefined 1 Reply Last reply Reply Quote 0
                • Marco_76undefined
                  Marco_76 @theruttmeister
                  last edited by

                  @theruttmeister
                  I had a similar idea, taking the advantage of a nema 17 with high torque on the bowden side, and a small nema 8 (80-100g) as additional direct stepper? Maybe with a 3:1 or 5:1 gear ratio. The idea is to help the small nema 8, which alone would not work. Is it so creazy?

                  Marco

                  theruttmeisterundefined 1 Reply Last reply Reply Quote 0
                  • deckingmanundefined
                    deckingman @aprz
                    last edited by

                    @1997alex In answer to your original question but without getting into any debate about whether it's a good idea or not, yes you can do that and you would not be the first to use two extruders in a push-pull arrangement. Configuration wise, you simply define a tool to use two extruders and then set the mixing ratio to 1:1.

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

                    Marco_76undefined 1 Reply Last reply Reply Quote 0
                    • Marco_76undefined
                      Marco_76 @deckingman
                      last edited by

                      @deckingman
                      Thanks Deckingman . I know I can configure two steppers to work in sync, but the question in fact is if it is a good idea or not and if there are specific issues with this configuration. As of now I'm using the flex3drive system but I found the worm gear very fragile (it's the second tyme I'm oredering replacements). The other option which I'm evaluating is to change the plastic worm gear with metal gears.

                      deckingmanundefined 1 Reply Last reply Reply Quote 0
                      • deckingmanundefined
                        deckingman @Marco_76
                        last edited by

                        @Marco_76 My comment was addressed to the OP, not to you. However, in answer to your question of whether its a good idea or not, it depends on the usage case. If you have an extruder that doesn't grip the filament well, and if the incoming filament runs through a long tube which may or may not have bends and thus induces friction in the filament path, or if you use large heavy reels of filament which do not rotate easily, then a push-pull extruder arrangement will help. Personally, I use Bondtech BMG extruders (6 of them) mounted on a second gantry which tracks the hot end, and my (6) filament reels rotate freely, and I don't use PTFE tubes on the inlet side of the extruders, so a push-pull arrangement is not necessary in my usage case.

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

                        Marco_76undefined 1 Reply Last reply Reply Quote 0
                        • Marco_76undefined
                          Marco_76 @deckingman
                          last edited by

                          @deckingman
                          interesting solution. Is there any picture or schema which show this?

                          deckingmanundefined 1 Reply Last reply Reply Quote 0
                          • deckingmanundefined
                            deckingman @Marco_76
                            last edited by

                            @Marco_76 said in Direct drive extruder and Bowden extruder on one machine?:

                            @deckingman
                            interesting solution. Is there any picture or schema which show this?

                            Shows what? Do you mean the extruder gantry? If so then I guess you want to know more about my CoreXYUVAB printer. Plenty of information on my blog and YouTube channels which are linked in my description.

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

                            Marco_76undefined 1 Reply Last reply Reply Quote 0
                            • theruttmeisterundefined
                              theruttmeister @Marco_76
                              last edited by

                              @Marco_76 said in Direct drive extruder and Bowden extruder on one machine?:

                              @theruttmeister
                              I had a similar idea, taking the advantage of a nema 17 with high torque on the bowden side, and a small nema 8 (80-100g) as additional direct stepper? Maybe with a 3:1 or 5:1 gear ratio. The idea is to help the small nema 8, which alone would not work. Is it so creazy?

                              Marco

                              Not crazy... but I don't think you get much from that. A NEMA8, even with a gearbox, puts out such a tiny amount of torque that I don't think there's much benefit over a plain Bowden drive. But I've not tried it, so I don't really know for certain.
                              Its also easy enough to use decently large X/Y motors and a direct drive NEMA17... unless you really really want to go really fast.
                              Oriental motors make a really nice NEMA11 (actually not true NEMA bolt spacing... but anyway) with a 10:1 spur gearbox, its insanely expensive, but makes for a nice light direct drive extruder. Puts out ~42oz-in of torque. Its a bit long with that gearbox, but it works nicely.

                              https://catalog.orientalmotor.com/item/stepper-motors-motor-only/legacy-pkp-series-2-phase-bipolar-stepper-motors/pkp223d15a-sg10-1

                              I expect that the issue with a push/pull setup is going to be the stretch/compression in the bowden... if you have too much, the small motor may run out of torque. With the tube stretching/compressing to effectively absorb the extra torque from the larger motor.
                              Because the motors are running in sync, you might not gain anything at all... in a perfect world you would want to 'pre-load' the bowden tube, so that 100% of the torque from the large motor is being used for extrusion.
                              It might be that the natural 'spring' that is micro-stepping will absorb that variation.

                              Its would be fun to design and try such a setup.

                              Isolate, substitute, verify.

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                              • oliofundefined
                                oliof
                                last edited by

                                someone once linked a two-in-one setup with two bowden feeders and a direct feeder here on the forum, which is one application where I see this could be beneficial: decent control of the retracted filament that's not used, and nice short retracts on the print head.

                                <>RatRig V-Minion Fly Super5Pro RRF<> V-Core 3.1 IDEX k*****r <> RatRig V-Minion SKR 2 Marlin<>

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                                • Vetiundefined
                                  Veti
                                  last edited by Veti

                                  on verrf there was a presentation from ldo about their motor for the orbiter extruder

                                  https://www.thingiverse.com/thing:4223085

                                  Gear ratio - 7.5 (new option 7.2)
                                  Filament pushing force 120Ncm - 12.4 Kg
                                  Filament acceleration up to 660mm/s^2
                                  Retraction speed: 60mm/s
                                  Overall weight is about 140g
                                  

                                  the stepper motor is 70g

                                  theruttmeisterundefined 1 Reply Last reply Reply Quote 0
                                  • theruttmeisterundefined
                                    theruttmeister @Veti
                                    last edited by

                                    @Veti

                                    Nifty.

                                    I'd be worried about the long term durability of what looks like printed gears in that gearbox...
                                    But I've bought enough LDO motors over the years to trust them (even if I would plan for those gears wearing away...)

                                    3D printing really has made custom gears the easiest thing in the world!

                                    Isolate, substitute, verify.

                                    1 Reply Last reply Reply Quote 0
                                    • Marco_76undefined
                                      Marco_76 @deckingman
                                      last edited by

                                      @deckingman Impressive, I've seen your videos on your channel. I finally made my two flex3Drive working but I will take it as next generation, when I want to modify again my COREXYU 🙂

                                      deckingmanundefined 1 Reply Last reply Reply Quote 0
                                      • deckingmanundefined
                                        deckingman @Marco_76
                                        last edited by

                                        @Marco_76 said in Direct drive extruder and Bowden extruder on one machine?:

                                        @deckingman Impressive, ...........................

                                        Most people say "crazy" - (and they are probably right) 🙂

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

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                                        • dragonnundefined
                                          dragonn
                                          last edited by

                                          It does make sense, I am using it right now.
                                          I have a light Nema 14 direct drive and a large nema 17 bowden.
                                          The whole point of that bowden is to feed the filament inside the printer enclose so the small direct drive doesn't have to work so hard to get the filament.
                                          They is one big problem with that, it is hard to get the ratio perfectly, a slight amount to low on the bowden extruder and after some hours of printing it will span the filament bowden the bowden and direct drive. A small amount to much and it will tangle inside the printer enclose.

                                          T3P3Tonyundefined 1 Reply Last reply Reply Quote 0
                                          • T3P3Tonyundefined
                                            T3P3Tony administrators @dragonn
                                            last edited by

                                            @dragonn said in Direct drive extruder and Bowden extruder on one machine?:

                                            They is one big problem with that, it is hard to get the ratio perfectly, a slight amount to low on the bowden extruder and after some hours of printing it will span the filament bowden the bowden and direct drive. A small amount to much and it will tangle inside the printer enclose.

                                            Presumably the way to fix that is to use a trigger or two setup to measure the filament tension and then as the tension increases, feed a bit more filament. This can either be adjusting a constant feed from the pusher (ie. M220 + 0.1% ) or a simpler option is a loop of filament that as the loop reduces to a certain amount the pusher pushes until the loop increases past a certain amount. AFAIK thats how (some) filament extruders manage the spooling function.

                                            Anything that relies on perfectly aligning extrusion rates of long print time is bound to be very difficult to calibrate.

                                            www.duet3d.com

                                            dragonnundefined 1 Reply Last reply Reply Quote 0
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