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Rotation design

  1. Apr 18, 2013 #1
    Hey guys looking to design something that will rotate a 2kg discus in place. I attached a simple schematic of what it will look like. I also don't know what kind of motor to use to rotate the shaft. I went to Fry's but their motors looked to weak to power it. Anyone know a site I can buy a motor that can get the job done for me?

    Attached Files:

  2. jcsd
  3. Apr 19, 2013 #2


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    Staff: Mentor

    Hi dt1156! [​IMG]

    One major omission in your specifications: the speed range over which you wish to spin it. Also, would be worth pointing out your discus's diameter.

    Are you planning mains operation, or a low voltage? My first thought is a ceiling fan motor and speed controller, but take great care, because a smooth discus is going to offer far less resistance than a big fan, so the discus will have a much faster top speed. This could be dangerous.

    To what purpose will you put this spinning disc?
    Last edited: Apr 19, 2013
  4. Apr 19, 2013 #3


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    A fan is a good idea. My first thought was to hit a surplus store or scrapyard and grab an old vinyl record turntable. You already have 2 or maybe 3 mechanically selectable speeds, with the option of adding an electronic controller. It has the advantage of needing only a restraint such as a couple of straps or some Velcro as opposed to an entire mounting system.
  5. Apr 19, 2013 #4
    The discus's diameter is 9in, 5/16" screw size and weights 2kg and round shape. I've included a picture of a discus that looks very similiar to mine. The point of this design is to create a test to gather data from the discus while it is in rotation without having anyone actually throw it. This is a group project where my group will be placing an acceleramator inside the discus and a programming a microcontroller to convert the acceleration readings into the distance the discus traveled. I'm just designing this rotational test part.

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  6. Apr 19, 2013 #5


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    .... One major omission in your specifications: the speed range over which you wish to spin it. [​IMG]
  7. Apr 21, 2013 #6
    Not much faster than the average rotational speed of a discus thrown by a olympic athelte. I couldn't find any measurements of a discus thrown by olympians so I asked my group and someone took a guess at around 10 revolutions per sec which is around 62 rad/s.
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