Building the C-Bot 3D printer: Part 29 : Rearranging the Leadscrews

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The C-Bot build instructions have you create a cantilevered build platform, with two rear leadscrews to drive it up and down.  Other designs have modified this to have a triple-leadscrew system where two screws are in the back, and one in the front:  This provides for better stability for the cantilevered build platform.  I’ve noticed on my larger prints a bit of “bounce/vibration” that happens on the platform as it drops over the lifetime of the print.  It would make sense that attaching the front to something would reduce this.

I seriously contemplated going to a triple-leadscrew system, but this would involve buying more hardware, cutting another leadscrew, etc.  Not the end of the world, but I’d like to work with what I already have.  I got to thinking:  Why not just take one of the rear leadscrews and put it in the front?

That’s what I did this afternoon, and so far, it’s worked out really well:  I had a long enough 20×40 cutoff I was able to put across the front of the build platform, and some spare printed corner-brackets to mount it in-place. From there, I took the right-rear leadscrew and moved it to the center.  Then I took the left-rear leadscrew and moved it to the new front location.

leadscrew_rearranged

Things noticed so far:

  • Build platform is much more rigid.
  • It’s easy to raise\lower the front\back for bed leveling by just twisting the leadscrews.

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Building the C-Bot 3D printer: Part 20 : Electronics Day 3: Swapping stepper drivers
    • Obor
    • November 28th, 2015 1:33pm

    Hi,
    Very interesting, double leadscrew as you suggest seems better because it drives the two opposite sides of the bed. Also, I found the triple leadscrew too complex (may be I am wrong). I am now thinking to build a large C-bot (600×300) and plan to use the 2 leadscrew as you did, but
    I wonder if there should be placed on large sides (600mm) or small sides (300)… ?

  1. @Obor
    Nice thing about this bot is its easy to reconfigure: You’re not ‘locked in’ to a certain configuration, even after you ‘finish’ it. If one way doesn’t work, try another.

  2. I have designed a Z-axis that may be more accurate by basically using one stepper motor, 4 lead screws and 2 or 4 idlers. Can I send you a png file and if you think you might want to try it out, I can send you the step or stl files (or Autodesk Inventor files if that is what you use.

    Don

    P.S. Are you near Silicon Valley?

  3. Sounds slick : Right now I’m happy with this setup and moving onto other projects (can only noodle on this thing so long), but I’d be happy to give them a look! And yes, I’m right near Oracle :)

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