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Help with Motor voltage/torque for 12 Newtons of force...

  1. Dec 16, 2015 #1
    Hello all, I'm going to get right to the point!

    My current project is a motor-retracted spring-loaded toy lightsaber. I started with one of those spring loaded lightsabers that spring out at the touch of a button... but it had the annoying immersion problem that in order to re-load it, you had to physically touch the blade to push it back in. So I gutted the lightsaber to make room for a 6 volt motor, attached it to the hilt, spooled a string around it, passed the string through the spring latch, and connected it to the loading mechanism attached to the top of the telescopic blade. Since I hadn't attached a battery to it yet, not knowing if it would even work, I tested it with a power supply and accidentally used 10 volts instead of 6 (oops!). Regardless of that, it worked beautifully and doesn't even look that ugly!

    However, it doesn't work quite as much as I had hoped. You see, it pulls the blade back... but it can't pull it all the way back against the spring's resistance, so is doesn't reload and there still a portion of the blade sticking out of the handle.

    So I need a new (bigger) motor that can bring the blade in even in spite of the spring resistance. I decided I would measure the exact force it takes to completely close the spring, and I discovered it takes approximately 12 newtons of force. Unfortunately I haven't found anything on the web that can translate that into what sort of motor voltage or torque I would need to reach that amount of force.

    What sort of advice to you guys have for me?

    -Aspirant
     
  2. jcsd
  3. Dec 16, 2015 #2

    anorlunda

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    Mechanical advantage, as in gears or pulleys, can multiply the force at the expense of speed.
     
  4. Dec 17, 2015 #3

    jim hardy

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    even just wrapping the string around a smaller pulley.
     
  5. Dec 17, 2015 #4
    Is there anyway that I could get a superior motor without having to throw gears and such into the system? Or is there no small sized motor with that kind of power?
     
  6. Dec 17, 2015 #5

    anorlunda

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    What kind of power do you mean? It's hard to answer your question because you don't say how much power you have or how much you need.
     
  7. Dec 17, 2015 #6

    rbelli1

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    Ditch the spring and make the motor do both actions.

    BoB
     
  8. Dec 17, 2015 #7

    CWatters

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    To work out the power you need to know the pulley diameter and rpm in addition to the force.
     
  9. Dec 17, 2015 #8

    rbelli1

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    How many sections is the "blade" constructed from?

    BoB
     
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