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Dual Direct Drive Extruders Concept

Discussion in 'Mods and Upgrades' started by Tony Janus, Nov 8, 2014.

  1. Mike Kelly

    Mike Kelly Volunteer

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    Right that was all said assuming dual bowden. Just keep in mind I don't think it's possible to set different extruder steps per mm for different cold ends.

    Here's a mockup of what I envision doing. It's quick and dirty and the EZStruder was used as representation of a cold end only.

    bowden+direct.PNG
     
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  2. Magic-Goat

    Magic-Goat Member

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    Ooohh, I've been waiting for one of these, really want to be able to print flexible materials; slowing down the print doesn't bother me too much. I hope there's a way around changing the steps separately
     
  3. Tony Janus

    Tony Janus Member

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    Alright I'm starting to get confused now. I'm going to have to look over everything for a while and try to get what you're saying here. It sounds like a geared extruder like wades vs a bowden extruder would require different step settings?

    or, oh I think I just got it, you're saying the firmware most likely doesnt support the difference in steps between 2 different extruder designs? so conceivably, having one on the carriage like the image you posted, and then one mounted to the case with a bowden tube, as long as they are the same extruder design and motor, should work? Though, the EZstruder isn't meant to be in parts list, just visual representation.

    So basically, any extruder that could provide the torque required from both directly above the hotend, and outside the case, as long as it will fit and not put too much imbalance into the carriage, should work, as long as both extruders are identical??

    I'm sorry if I'm not getting it, I've had a long, difficult few weeks.

    I'm also unable to find the files for any of the other designs besides what on thingiverse, but you said those are not the most up to date. Are the new files uploaded anywhere?
     
    #23 Tony Janus, Nov 11, 2014
    Last edited by a moderator: Nov 11, 2014
  4. Stargrove1

    Stargrove1 Member

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    Thanks, you could be right by shipping costs. How do you deal with the different shaft diameter, standard Nema17 has 5mm, the gear has 6mm? Using different filament gear?
     
  5. Tony Janus

    Tony Janus Member

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    So, I'm not sure what all the different designs are called out there, but is the Robo3D based on Prusia? Cause from what I've seen, the Robo3D and Prusia i3 look pretty much identical in terms of mechanics.

    If this is true, then a dual wades may have already been solved. Just found these, wondering if it'll work, and if it could be adapted to a bowden/wades setup easier than what you're working on.

    Extruder: http://www.instructables.com/id/Build-a-Dual-Extruder-for-3D-Printing/
    Carriage: http://www.thingiverse.com/thing:93513

    Looking at the carriage, it doesn't seem to have the build quality that yours and others do, and it doesn't seem to have hotend height adjustment, but it doesn't look too difficult to modify. Honestly, I like the look of your concept the best, but if this is easier and just as effective? Figured I'd share anyways.
     
  6. Mike Kelly

    Mike Kelly Volunteer

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    Essentially yes. If your extruder designs are different they'll have different steps per mm. That's why it's best to have the same design on both, as you described.

    There are ways to get around this limitation but it's a bit too hack-ish for my liking. I would prefer something in the firmware instead of things like adjusting filament diameters etc.

    I haven't uploaded the files anywhere but I can start collecting them for you if that's what you'd like. I poked around with the idea of a direct feed extruder that hooks up to the nema 17 geared stepper motor i'm using. I wasn't too happy with what I was coming up with, nor did I feel up to the task of designing a custom extruder, so that's gonna be a bit of a backburner.

    If you are interested in starting to print out the parts send me a conversation and I can generate them for you. There's a few bits of hardware you'll need to buy as well
     
  7. Mike Kelly

    Mike Kelly Volunteer

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    I stuck my hobbed pulley on a lathe and drilled it out to 6mm. That was probably overkill since the hole's already there and will naturally stay true. So just put it in a chuck and drill it out to 6mm would be my suggestion.

    I've seen hobbed pulleys with 6mm ID's but the company that sold them is out of business now and I haven't come across any since.
     
  8. Mike Kelly

    Mike Kelly Volunteer

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    The RoBo is probably closer to the mendel90 than the Prusa i3 but according to team robo it was something they dreamed up.

    Might be closer to the Prusa i2 which I think had the X axis rods the same way as the robo. Interestingly enough the design they sold us on for the kickstarter was closer to the prusai3, but that's a story for another day.

    Most people don't take into account nozzle height adjustment, which is why a lot of people struggle with dual extruders.. They tend to assume the nozzles will be exactly equal, which is pretty much impossible.

    I do like how compact the flying motor is, but my ultimate goal with dual extruders was to gain X travel while adding duals. Thus I try to avoid things that push me over the 50mm I'm currently sitting at.
     
  9. Stargrove1

    Stargrove1 Member

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    I'll probably do the same with more overkill than you, take it to the sample dept. and let our mechanic do it on lathe to ensure it stays fully centered :)

    I also found one or two selling them with 6mm, but the price wasn't right for me.

    Thanks for the motor link, both motor and pulley are on the way.
     
    #29 Stargrove1, Nov 12, 2014
    Last edited by a moderator: Nov 12, 2014
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  10. Magic-Goat

    Magic-Goat Member

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  11. Mike Kelly

    Mike Kelly Volunteer

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    Holy hell his printer is fast! I assume that must be a timelapse because it seems almost impossible to move that fast.

    That's a slick design, but in order to adapt it to the Robo you'd lose X travel. Though in principle it would probably be the same as with the stock greg's wade. I've been eyeing this design: http://shop.uniqueprototyping.com/V...per-Extruder-No-Motor-or-Pulley-EXT-31-XX.htm as something to base mine off of. They haven't released the files but the assembly guide gives me enough information to go on.
     
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  12. Magic-Goat

    Magic-Goat Member

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    Yeah i thought the same thing, if it was really that fast the frame would probably be shaking all over the place :p

    Well I'm really interested in a hybrid design/dual direct, i want to be able to print with support with the option for flexible materials and a slower print doesn't bother me too much. I'm happy to test out a design for you although I'd probably need guidance for the technical stuff
     
  13. Mike Kelly

    Mike Kelly Volunteer

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    Sure, shoot me a PM if you're ready to start printing stuff and I'll send you the files.
     
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  14. Galaxius

    Galaxius Well-Known Member

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    That's a nice design. I really like the tension spring setup. Must find/create something for the wades extruder. No more springs & bolts flying across the room.
     
  15. Magic-Goat

    Magic-Goat Member

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  16. Mike Kelly

    Mike Kelly Volunteer

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  17. Magic-Goat

    Magic-Goat Member

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    Their website says it's compatible with a majority of printers that run G-Code with standard filament. Probably will be pretty highly priced though, find out in a couple on months :p
     
  18. Mike Kelly

    Mike Kelly Volunteer

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  19. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Yea, the cyclops is from a known quantity (of quality).
     
  20. Magic-Goat

    Magic-Goat Member

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    Oooh, i hadn't seen this! Can't wait to see some pics of how they've set it up
     

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