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Dual Direct Drive Extruder

Discussion in '3D printers' started by Keith Davis, Jun 10, 2020.

  1. Keith Davis

    Keith Davis Veteran
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    Keith Davis published a new build:

    Read more about this build...
     
    JustinTime likes this.
  2. JustinTime

    JustinTime Journeyman
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    Keith, you think that two cooling fans, blowing on each other, will cool better than a one fan mounted on the cooling fins?
     
  3. Keith Davis

    Keith Davis Veteran
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    Good catch, Justintime :thumbsup:. 3D's Chimera comes with a 30x30 mm fin fan that screws right into the fin blades. My pics do not show that fan.
     
  4. peer23peer

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    Are you planning on dual extrusion at the same time? Given you have two NEMA 17s as actuators. That is a lot of extra weight that you will be carrying. And that extra weight needs be supported with a stiffer frame, which in turn slows down your gantry acceleration or it will introduce unwanted vibrations. Or are you gonna keep your keep your print head locked and move your bed, which will result in a much smaller buildvolume. Either way it might be worth it to see if you can get away with one actuator for the direct drive.
     
  5. Keith Davis

    Keith Davis Veteran
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    Correct, this would never work on a flimsy printer by Anet, Prusa, or Creality. It would require a solid, rigid z axis frame using aluminum extrusions
    with V-wheels for the Z gantry. such a frame is a structurally sound as a Y axis which carries far more weight. Something like Vulcan Pro V2
     
  6. peer23peer

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    Good to know you weren't planning on using flimsy printer constructions ;-) Just keep in mind that bowden-tubes, with all their flaws, are used for a reason. A common mantra we often say at Ultimaker is: "You have to carry and accelerate every gram on the printhead". Extra mass can result in a degraded print quality but at the very least requires an upgrade of the motion system as a whole. A lessen I learned when working on a couple of prototypes for our next gen. printhead (also direct drive).
     
  7. Keith Davis

    Keith Davis Veteran
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    You have to ALSO carry and accelerate every gram on the BUILDPLATE
     
  8. peer23peer

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    True its all about compromises, and every design choice has implication. One big interesting puzzle.
     
  9. Keith Davis

    Keith Davis Veteran
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    The main value of a direct drive dual extruder would be for printing flex filament, which can not be done cleanly with a bowden-tube and certainly not at high speeds.
     
    peer23peer likes this.
  10. Troy Proffitt

    Troy Proffitt Well-Known
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    I've been working on a dual extrusion setup similar to you, but the one I used is based on the bondtech process:
    Dual BMG Chimera+ for CR-10 by Festivejelly

    I modified it so that instead of the 2 50mm radial fans for parts cooling, I'm using a CPAP blower attached using a tube:
    dual_2.png dual_1.png 20200518_150858.jpg 20200611_134526.jpg
     
  11. Keith Davis

    Keith Davis Veteran
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    COOL Troy!!!

    What size motors are you using?
     
  12. Troy Proffitt

    Troy Proffitt Well-Known
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    Those are pancake nema 17s. Pretty light
     
  13. Keith Davis

    Keith Davis Veteran
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    Gee, and I have a case of those motors and have never tried one for an extruder :banghead: I will now!!
     
  14. Troy Proffitt

    Troy Proffitt Well-Known
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    Well the Bondtech BMG Extruder includes a 3:1 gear reduction which provides not only better accuracy, it also triples the strength of these small steppers. I really like gear reduction on both z axis and extruders since they don't move very fast during prints.
     

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