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Q: Torque-speed? Motors and rotating plinths - Please help!

  1. Jun 29, 2009 #1
    Dear engineering gurus,

    I was wondering if some of you might be able to help me out with my project (2 part question):

    I'm basically trying to make a rotating plinth (like those used
    in jewelry displays - except i need it to bear a weight of 1kg.
    (Most ready-made plinths wont take anywhere near that so i imagine id have to build my own.

    Now i've come across a small motor (MM54) that has the following info for its specs:

    Constant Volts: 6 - 9
    Speed RPM: 8900 - 16200
    Torque (g-cm): 174 - 236
    Stall torque (g-cm): 980 - 1800

    My first question is - would anyone know if this motor is powerful enough to take the weight of 1kg and still function?
    (Am i right to be choosing a motor that has a high torque speed?) Is there another motor that someone could recommend that would suit my purpose?

    Second question - As i need to bring this down to about 1 RPM, can anyone recommend a gearbox that will allow me to do this?
    (Is this even possible with the motor i'm suggesting?)

    Apologies if my questions seem a little inept - ive never done anything quite like this before. And i really really appreciate any help or suggestions...

  2. jcsd
  3. Jun 29, 2009 #2
    Go to www.ebay.com[/URL] and search for "gear motor". I got over 1000 hits. Some are around 1 RPM.
    Last edited by a moderator: Apr 24, 2017
  4. Jun 29, 2009 #3
    Hi Bob,

    Thanks for that.

    I found 2 other motors that (i believe) seem more appropriate:

    The one is: 12V, 1 RPM, 65 Stall-torque (in-oz)
    The other is: 12V, 2 RPM, 31 Stall-torque

    If i wanted to have a bit more control in the RPM, should i be getting
    the second one that is 2RPM and then get a dimmer-switch type thing to adjust it?
    Would that work?

    And also, what is the relation between my 1kg weight requirement and the 'stall-torque'?
    Is 31 stall-torque alot? does it equate to a weight capacity? Could i go for maybe something that has 7RPM but then only 16 stall-torque?

    Thanks again.
  5. Jun 29, 2009 #4
    1 kg is the just the vertical mass the unit has to support. The required torque is probably less than 0.5 inch oz (or maybe 10 gram-cm). If you get a dc one, you can adjust the speed by reducing the input voltage.
  6. Jun 29, 2009 #5
    Ah ok,

    So the 12V motor with 31 stall torque is more than 60x what i need to rotate the 1kg?


    Thanks again for the help Bob.
    Last edited: Jun 29, 2009
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