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Building machine to keep ball rotating

  1. Aug 29, 2014 #1
    I need a contraption that can keep a ball spinning, smoothly, at a slow speed. If it has a variable speed control, that would be better, but minimally it would need to spin a soccer ball and take around 30 seconds to make a full rotation. The look of the device doesn't matter, just that it mechanically works.

    Can anyone help lead me in the right direction on how I would go about building something like this?
     
  2. jcsd
  3. Aug 29, 2014 #2

    berkeman

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    Welcome to the PF.

    What is the axis of rotation? Is the axis horizontal, or vertical?
     
  4. Aug 29, 2014 #3
    Thanks! It would be vertical rotation, although if it doesn't complicate things much, having horizontal and vertical controls would be better. But vertical only would work for my needs.
     
  5. Aug 29, 2014 #4

    berkeman

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    What do you mean by "vertical rotation"? Does that mean the axis of rotation is horizontal, so it would be rolling in a motion like it was rolling on the floor?
     
  6. Aug 29, 2014 #5
    Correct, spinning along the X axis (horizontal axis) as though it were rolling on the floor.
     
  7. Aug 29, 2014 #6

    berkeman

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    Got it. So make a hoop about 1/2 the diameter of the ball, and put 3 captured ball bearing assemblies equally spaced around the circumference of the hoop. That creates a cradle that the ball can sit in and spin in any direction.

    Then use a geared-down electric motor with a roller under the ball to make it roll. The roller/motor height should be adjustable over a small range so you can just start to unweight the soccer ball from the ball bearing supports when making contact with the bottom of the ball. You should be able to find an adjustable geared-down motor so you can control the speed over some range.
     
  8. Aug 29, 2014 #7
    Let me start by saying I really appreciate the help. My mechanical knowledge is extremely limited, so hopefully you can bare with me. How would you suggest I go about finding an adequate geared-down motor with a roller? Would a common hardware store sell something like this or would I be looking at disassembling a device to remove the assembly?

    Your description sounds simple enough and with a simple wooden structure I can hold the ring and the motor in place to get the spin I need out of the ball.
     
  9. Aug 29, 2014 #8

    berkeman

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    I like to use Google Images to help speed up my searches for parts. I did such a search on:

    small electric motor with reduction gear drive

    and got lots of good hits. Maybe give that a try to see if you can find what you want (hopefully inexpensively via mail order). You can use a similar search to look for captured ball bearing assemblies.
     
  10. Aug 29, 2014 #9

    berkeman

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  11. Aug 29, 2014 #10
    Good tip. I'll give it a try and see. Thanks!
     
  12. Aug 29, 2014 #11

    berkeman

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    BTW, another option would be to change out one of the ball bearings for a roller. I'd make the roller roll down, I think, to help keep the ball held down in the ring. That's probably simpler than using 3 bearings and trying to tune the bottom roller to the right height.
     
  13. Sep 12, 2014 #12
    I found the encased ball bearings and have been looking for small geared-down electric motors w/ rollers but so far haven't made much progress. Where I'm getting stuck at are a few things:

    What do I plug the motor into?
    How do I adjust the speed on a motor like this?
    Where can I buy a motor like this that would work for my needs (I still haven't found a retailer with one that looks right for my needs)
     
  14. Sep 13, 2014 #13

    Dnomyar

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    Getting electric motors with the right fitting isn't easy, but most Hobby Electrical shops will sell you a gearing kit ( Tamiya is popular). the can also supply speed controller - the ones used in Slotcars would work.

    You can attach rubber wheels, or even model tank tracks to the output shafts.

    Another option would be to direct a stream of air from a vacuum cleaner that has a 'blow' attachment, or even the suction end might work.
     
  15. Oct 4, 2014 #14
    I had assumed this would be simpler, or someone could help guide me a little better to what parts I need. I went to a couple electronics component stores and each one tells me they can't guide me on what parts I need to put something like this together, I need a parts list.

    Can anyone tell me what parts I should be asking for? From what I can tell, in order of how they're connected, it should be something like this:

    Power supply -> Control to adjust power output (speed of motor) -> Motor -> Gear -> rubber wheel

    Obviously I'm not understanding enough and the stores here don't seem to help much. So can someone with knowledge of these things possibly explain exactly what I would need to do this?

    Thanks.
     
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