Twicx's Dual E3D Direct-Drive Extruder

Discussion in 'E3D-v6 and Lite6' started by twicx, Mar 6, 2014.

  1. twicx

    twicx Well-Known Member

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    Hello all!

    So I'm working on a whole load of mods for my existing Felix 1.5 Rev E. The core to these mods is a new Z-Axis system with a more centralized axis of movement, and a Dual E3D Direct-Drive Extruder, powered by a new RUMBA board. So far, progress has been mixed. The compact design of the extruder means I'm doing a lot of testing with my current setup, and work is very busy, which cuts into the time a lot. The 2 x V5 hot ends will be driven by 2 x NEMA11 Geared motors, with a trinity labs hobbed pully. The bearing wheels for them are based on a reverse-spring mechanism, which means that there will be a spring between the two arms essentially pulling them both into the hobbed pully. That's proving to be the most difficult bit to work out, but I'm making good progress on them over the last few days.

    I'm hoping to get all the extruder done, printed and assembled in the next 2 weeks, although I won't be wiring it up till i get the new Z axis done first. However, for those interested, the extruder progress as follows:
    [​IMG]

    I've done some successful test prints in PLA of the motor brackets, and the airduct, but the next thing is to get the base, bearing arms and the lock for the hot ends done. Hopefully have some new progress parts done by mid next week. :)
     
  2. twicx

    twicx Well-Known Member

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    So, some small updates today.

    Following today's delivery of PVA Filament, 2 x 0.25 Nozzles, and Haribo (gotta love the little details!), I now have all the parts. I've a list of parts to print for the extruder carriage. There's 9 in total for the extruder, which is probably a lot, but some of them, like the bearing arms, are very small. The tricky part will be figuring out good print temperatures and speeds for printing in ABS for the carriage base and lock (the part that holds the hot end in place.) I haven't used ABS before, but I'll do a little test print first, any tips on temperatures would be great.

    I think my best plan of action for this is also to get the gantry and box for the electronics printed soon after. I've a RUMBA board, a new motor, new thermistors, new Z axis spindle etc to go in too, and I think I'd be better off doing all the wiring and electronics in one go, rather than in bits and pieces. I've very little experience working with the firmware side of things, so it's kinda daunting!

    Pics of parts to follow tonight when I get home from work! :)
     
  3. Eaglezsoar

    Eaglezsoar Administrator

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    Nice design! ABS temperatures for me have average 210c - 230c
    Good luck in getting all of this working and like I said, I am impressed by the design.
    I can tell that you spent many hours working on this and it sure looks like time well spent.
     
  4. twicx

    twicx Well-Known Member

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    So after a particularly busy week in work, I'm back to printing parts today. Right now, I have the 2 bearing arms, vent and back section of the motor brackets printing. All that's left after that is the extruder base and feeder cover and it'll be ready for assembly! Slow progress, but it's getting there!
     
  5. Eaglezsoar

    Eaglezsoar Administrator

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    It will be nice to see some pictures of the finished product.
    Congratulations on getting as far as you have.
     
  6. twicx

    twicx Well-Known Member

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    Thanks! I would like progress to be quicker, but it's the kind of thing to go slow with to make sure I get it right! In any case, here's more or less the full compliment of parts involved (except for the 2 x 0.25 e3d nozzles I left on my desk in work!) which shows the motors, hobbed bolts, hot ends, fans, new RUMBA board, the front part of the motor brackets, various screws etc and the new Z axis components
    [​IMG]

    and a pic of today's prints, which are coming along nicely! It also shows the old extruder which will soon be replaced. I like that the new extruder will be smaller in the direction of the Y axis, but a bit deeper away from the metal frame, which isn't a problem. It's more or less the same weight, but it still goes back to the idea of having a direct-drive dual extruder over a bowden one to make it easier for things like flexible filament.
    [​IMG]
     
  7. Eaglezsoar

    Eaglezsoar Administrator

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    Very nice! Thanks for posting those, and all the hard work.
     
  8. twicx

    twicx Well-Known Member

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    so I'm making serious progress today. Tensioner mechanism assembled, but I think I'm going to change to a higher-tension spring than what I have.
    [​IMG]
     
  9. Sanjay

    Sanjay Administrator
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    This is really awesome work! Well documented, - you're definitely in the runnings for a prize with this grade of thread! Keep up the good work.
     
  10. Eaglezsoar

    Eaglezsoar Administrator

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    Those stepper motors that you are using usually have an 8mm shaft, did you use a MK7 drive that you bored out to 8mm?

    That assembly looks awesome and I'm sure it will work well. The tensioning springs may need some tweaking but the design
    looks very solid.
     
  11. twicx

    twicx Well-Known Member

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    They're actually a 6mm diameter shaft on them, so I went with trinity labs' 6mm hobbed pulleys and they fit perfectly.

    Yeah the springs are ok at this stage, but I'm going to hop into my hardware tomorrow to get springs with higher tension. I could see myself making a Mk2 version of this, with a way of adjusting one of the end points of the springs to increase/decrease tension, but it's fine for the moment. I'm sure there will be a lot of tweaking once it's done, but it's getting there!
     
  12. Eaglezsoar

    Eaglezsoar Administrator

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    May I ask what the motors are that have the 6mm shafts. I have never seen them before.
     
  13. twicx

    twicx Well-Known Member

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  14. Eaglezsoar

    Eaglezsoar Administrator

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    Thank you! I have never seen 6mm steppers that were geared.
     
  15. twicx

    twicx Well-Known Member

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    Yeah I've seen a few extruders that use them. there's a Micron extruder that uses 13:1 gears, and I've seen a few using the 5:1 ones that I went for. It was an effort to keep the size down, but they're still relatively heavy. BUT, as far as dual direct-drive extruders go, I think its still pretty compact.
     
  16. Eaglezsoar

    Eaglezsoar Administrator

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    Most of the geared steppers are 8mm shafts, this one is quite a find with 6mm.
    I definitely will be getting a couple of them.
     
  17. twicx

    twicx Well-Known Member

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    The toughest decision I had was whether to go with 5:1 or 13:1 for the ratio. The micron one (http://www.3ders.org/articles/20131231- ... icron.html) uses the 13:1, which although would allow for more torque, the print speed would have to be a bit lower. So, I figured that 5:1 with good tension (looks like these springs should do it) would not only allow enough filament to flow, but would allow for better speed than the 13:1. Also, I think that because I'm using 1.75mm filament, there's less material going through than a 3mm system, so I think hope that the 5:1 will be ok!

    I'm still a little apprehensive about the electronics side of things. I'm very new to messing about with the firmware etc, and at the moment, I'm looking at that Cura software as opposed to Repetier host. It seems to be building a VERY good reputation so far.
     
  18. twicx

    twicx Well-Known Member

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    actually, on the issue of working with a new rumba board, it seems like it would be worth my while to do a wiring/function test before final assembly. Out of interest, how difficult would it be to wire everything up, not assembled and do tests to get things like motors, hot ends etc tested?
     
  19. Josh

    Josh Administrator
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    You definitely made the correct decision with the 5:1 - 56Nm Holding Torque is more than enough and going any further would severely slow you down and make retraction less effective.

    Regarding the firmware - why not just stick to Marlin? At least at the outset. In terms of slicers I use a combination slic3r and Cura depending on the application. Probably easiest to stick to Slic3r to start with since it is bundled in with Repetier Host.

    No reason not to test before you get everything onto the printer if you are wanting to be cautious. Just remember to never have a stepper driver plugged in without a motor attached. Doing so risks blowing the driver! We often test HotEnds off printer - just don't get burned, I have a few war wounds myself!
     
  20. twicx

    twicx Well-Known Member

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    Yeah its one thing to get a burn from a hot end, from an electrical component is worse! I used to build/repair guitar pedals and amps. 400 degree soldering iron burn, not fun haha!

    Also, looking at the RUMBA wiki, is there any reason why someone wouldn't do 1/32 microsteps? does it depend on the motor to support microstepping?
     

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