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Seeking ideas on how to rotate a plate (think lazy susan)

Discussion in 'General Talk' started by PrintHead, Nov 22, 2016.

  1. PrintHead

    PrintHead Well-Known
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    I am trying to add a way to angle a tool and it would be fantastic if there was some sort of plate which I could rotate on top of another plate using the help of a stepper and worm gear. Not sure if there's a name for this but I'm leaning towards "lazy susan bearing" except with a bit of preload on the bearings and less wiggle.

    Has anyone seen such a thing made using OpenBuilds stuff?
     
  2. PrintHead

    PrintHead Well-Known
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    The Black Friday sale is almost here and I'm really hopeful there's a way to make this happen. Surely I'm not the only one to want to put something on a hinge :)
     
  3. Rick 2.0

    Rick 2.0 OpenBuilds Team
    Staff Member Moderator Resident Builder Builder

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    Rough concept sketches showing sizes and weights would be helpful. The issue here is how you plan to integrate a worm gear as the upper plate is generally attached directly to it where one is used and thus no need for any kind of lazy susan bearing. If you were wanting a belted solution this would be easy, just not following how you plan to integrate the worm gear.
     
  4. PrintHead

    PrintHead Well-Known
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    I'm not dead set on it being a worm gear that's just the first thing that came to mind (belts would be fine) I just can't seem to figure out how to make something rotate using the OpenBuilds components. Picture a small palm router mounted using one of the OpenBuilds mounts, except I need to tilt it somehow. There isn't a concept sketch to share because I can't seem to get that far :)
     
  5. crispin

    crispin Journeyman
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  6. PrintHead

    PrintHead Well-Known
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    Thanks for the tip! This is sort of what I was after but I need it to be a lot more rigid. It was for what I believe would be called a B axis. Perhaps 2 of these with a double-ended servo could get closer to what I was after. Thanks just the same crispin!
     
  7. crispin

    crispin Journeyman
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    aw that poor lil hub just can't get no build love! but won't you reconsider? it's really quite a fine piece of OB kit and is entirely under-used for such a unique connector. Yours might still be the first build to ever use the piece.. and our lil Mounty just might be perfect for your machine!

    It's only the size of a postage stamp but has the thickness of the mini plate, thicker than the standard plates. The corner holes are threaded to make a solid connection to whatever you need to rotate around the unthreaded center hole with it's 2(!) grub screws for secure attachment to your motor spindle. Mount the assembly slightly off-center to your axis plate and you've got a robust actuator using a real stepper instead of one of those cheap plastic servos.
     
  8. Rob Taylor

    Rob Taylor Veteran
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    For hanging something putting out about 800W of power, I'd probably bite the bullet and construct an actual "spindle" with thrust bearings. You can clamp the bearings each side of the motor mounting plate for the preload, which could be 1/2" aluminum (or maybe 3/8" steel, for better vibration characteristics), and then attach a mounting plate to that shaft (I'd go at least 1/2"/M12) with a keyway and grubscrews (since broaching keyways internally is tricky without some expensive broaches or an even more expensive shaper).

    Basically, imagine that I'd done my z axis motor plate properly, instead of relying on gravity (because I can get away with it it in this use case):

    MG_5040.jpg

    (There's a bearing inside the large pulley) Which would give you a stack that looks like this:

    B-axis_Spindle.jpg

    The only tricky part here which might require real machining would be those green discs- they're acting as washers between the two orange nuts, but also as spacers which are keeping the threaded axle perfectly centered in the bearings on both sides. They'd be a quick'n'easy lathe part though, you could probably send out for them for cheap from some local job shop (assuming you don't have machining capabilities at home). Technically you could buy bearings which have the same size through-hole as your threaded rod, but they'd be narrower, and therefore less stable under load.

    Thrust bearings like that aren't super cheap, but VXB would have some for a reasonable price, I'm sure. They'd be plenty good enough for a simple build.

    Edit: Heh, just noticed the necropost. Info still stands, though! :p
     
    #8 Rob Taylor, Feb 27, 2018
    Last edited: Feb 27, 2018
    crispin likes this.

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