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Bi-Motion Box Printer

Discussion in '3D printers' started by Keith Davis, Sep 7, 2017.

  1. Keith Davis

    Keith Davis Master
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    Keith Davis published a new build:

    Read more about this build...
     
  2. JustinTime

    JustinTime Master
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    I had bad experience with these linear bearings. I used both cheap Chinese ones and more expensive US bought ones and the failure rate on both batches was horrendous. 50% or more. I used the 8mm ones. Maybe the bigger ones are better.
     
  3. Keith Davis

    Keith Davis Master
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    I think you would probably experience failure with using linear bearings in place of rotational bearings if the bearing was was being used to position the linear rod. In this usage the rod's position is defined by regular bearings at both ends and the linear bearings "allow" rotation while carrying the weight of the center rods and extruder. I actually use 45mm long bearings (although the drawing shows only 25mm ones) that have the ball rows in a spiral instead of straight lines.
     
  4. Rob Xaos

    Rob Xaos New
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    I like this elegant and solid design. I will very likely use it as inspiration for a build of my own.

    Some suggestions:
    I would double up on both pink rods (I'm a rigidity advocate)
    I would mount the drive motors at the top and directly couple them to the yellow fuscia rods. Although that would not be as visually tidy as your design it would eliminate a number of moving parts.
     
  5. Burning-man

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    sorry for my lack of knoweldge, but what software did you use to build your printer? and where can you find a dual extrusion hotend like in your picture?
    Thanks
     
  6. Keith Davis

    Keith Davis Master
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    I used Sketchup Make. That dual hot end is a Chimera. Google it by that name.
     
  7. Steve Jeppesen

    Steve Jeppesen Well-Known
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    Nice work Keith.

    Can't imagine a whole lotta air will be moving thru up to two, 4mm OD x 3mm ID tubes, that would be cooling the part down. I've nothing to back it up but gut feeling thinks you should try for a much larger ID/total volumn soultion - but who knows LOL
     
  8. Keith Davis

    Keith Davis Master
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    I saw this on a high end printer a couple if weeks ago. At the time I didn't think too much about it so I don't remember which one it was. I don't have any 3mm ID so I hooked up a 50mm blower fan to a 2mm ID tube yesterday and it delivered a pretty strong jet stream.

    I saw it when I was searching for clues as to why some desktop printers sell for $2500 while most others are 2 grand less. I have a customer (TrueUp LZ) who's company is looking to buy a dozen Ultimakers, so...... Of course Ultimaker's obvious secret sauce is their incredibly light X & Y system. But, Eric at Ultimaker pioneered the use of a bowden filament feed and there's a secret there too. It uses a 50 in/oz motor, but it's geared 3:1 so it delivers an incredible 150 in/oz power.

    Ahhh... found some 4mm ID 6mm OD PTFE tubing. Easy adaptation. Thanks Steve, I'll try it too.
     
    #8 Keith Davis, Nov 4, 2017
    Last edited: Nov 4, 2017
  9. Holy1

    Holy1 New
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    Hi Keith, I like what you are doing here. I am curious why you went from a 12" to an 8" build plate. Also had you decided what linear bearings you will be using?
     
  10. Keith Davis

    Keith Davis Master
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    Only because the "client" wants a 8" x 8" x 18" build area. LM8LUU (45mm long). I've had really good luck with this guy, the rod ends are polished to prevent damage to the bearing balls when putting them on. 2 x 8mm 15" Hardened Shafts with 2 LM8LUU Rod Rail Long Linear Bearing Motion | eBay
     
  11. Holy1

    Holy1 New
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    Thank you for the link. I didn't realize you were making it for someone. Keep up the good work.
     

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