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Motor selection

  1. Feb 18, 2010 #1
    I'm trying to figure out how to select a motor for a project. I want to spin an aluminum disk between 400 and 3000 rpm. How would I go about calculating the correct specifications for a motor?

  2. jcsd
  3. Feb 19, 2010 #2
    Since i don't know about your load. i suggest if you try with brush less DC motors because it is very good for precise speed controls.
  4. Feb 19, 2010 #3


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    Staff: Mentor

    Is this disk touching anything other than what is supporting it? If not, all losses are due to friction and those losses are extremely difficult to calculate (but are relatively small). Either way, if it is a small disk, a small dc motor will certainly give good speed control.
  5. Feb 19, 2010 #4


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    Homework Helper

    You'd probably want a dc "outrunner" brushless motor. These generate more torque at lower rpm than conventional dc motors. They're popular for radio control models. Do a web search for "radio control outrunner brushless motor" and you'll find quite a few site that sell these, along with specifications, like voltage, amps, torque, rpm, ...
  6. Feb 19, 2010 #5
    Thanks all.

    The disk will be made out of a 3.5 inch diameter .5 inch thick aluminum stock. It will be milled to 1/32 inch thick aside from the coupling that will attach directly to the motor shaft via two set screws.

    I want to attach some kind of controller to the motor to allow roughly 100-300 rpm intervals from 400 to 3000 rpm.

    The disk will be spinning perpendicular to the ground.

    What do you think would work best?
  7. Feb 19, 2010 #6


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    Homework Helper

    Brushless motors already require a controller just to operate, and a typical controller allows the rpm to be varied. You just need some feedback from the controller or from the motor to determine and modulate rpm.
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