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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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    • Phaedruxundefined
      Phaedrux Moderator @theruttmeister
      last edited by

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

      The closest is if you for some reason have a very long filament guide tube that imparts so much friction that you can't pull filament down it with just your extruder.

      If that's the case, just get a tube with a larger ID.

      Z-Bot CoreXY Build | Thingiverse Profile

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

        @Phaedrux said

        If that's the case, just get a tube with a larger ID.

        Diminishing returns... cable chain, multiple tight radius bends, long total length, TPU. But its an edge case.

        The solution was to beat it to death with a huge motor and a drive that doesn't slip! (and shorten and simplify the tube run). Prints got suddenly got 50% heavier... turns out the old head was not putting out anything like what it was supposed to.

        But for most people, yeah, a decent diameter bit of FEP and a good spool holder is all you need.

        Isolate, substitute, verify.

        engikeneerundefined 1 Reply Last reply Reply Quote 0
        • engikeneerundefined
          engikeneer @theruttmeister
          last edited by

          @theruttmeister @1997alex I think there is one other (very specific) occasion where you might be combining bowden & direct drive - a single hotend Y-splitter multi-material printer where you need direct drive (e.g. to print flexibles, or because you hate bowden). I'm thinking multiple bowdens connecting through a Y-splitter (similar to the original Prusa MMU), then a single direct drive extruder actually pushing the filament through the hotend.
          In reality here, the bowdens are more like loading devices to swap the active filament, whilst the direct drive is doing the brunt of the extrusion. You'd probably want to have the bowdens at quite low currents in normal running in case they are out of sync with the main direct drive extruder.
          Of course, there are many other reasons why this might not be a great design (filament clogging, lots of extruders etc) hence I've not seen one in real life, though there was someone else on the forum that mentioned they were working on one a while ago...

          E3D TC with D3Mini and Toolboards.
          Home-built CoreXY, Duet Wifi, Chimera direct drive, 2x BMG, 300x300x300 build volume
          i3 clone with a bunch of mods

          theruttmeisterundefined 1 Reply Last reply Reply Quote 0
          • 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

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                        • 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?

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                                • 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.

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                                          • 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
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