high torque low speed electric motor help

Discussion in 'Electronics & Electrics' started by Salad Fingers, May 31, 2010.

  1. Salad Fingers

    Salad Fingers (Banned or Deleted)

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    Hey all.

    Mate of mine is designing a mechanical motar and pestal for his final year project at uni. Both he and I suppose, are after some pointers/advice on what motor to use. Initially I though he could flog a motor out of a food prossessor but he'll need all sorts of gearing to reduce the speed and this adds complexity and more chances for parts to fail. I guess were after a bit of a heads up as to whats out there in terms of low speed high torque electric motors. I'm guessing this will restrict us to purely DC??

    Thanks.
     
  2. LostBenji

    LostBenji Member

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    R/C aircraft use very high torque brushless motors that can be modded and are not badly priced if you shop around.
     
  3. thrillhouse

    thrillhouse Member

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    What sort of movement did you want to achieve? Up and down motion, up and down with some twisting, just rotation of the pestle, etc.

    You could possibly use a high torque servo, or similar.
     
  4. Jesmol

    Jesmol Member

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    How about a seat height adjuster motor. Low speed work drive, capable of lifting pretty heavy weights.
     
  5. RussellK

    RussellK Member

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    An easy starting point would be a windscreen wiper motor as it probably already has enough gearing.

    What I'm not sure about, as others have suggested, is the movement required. I'd have though a mortar and pestle would require an eccentric movement in multiple dimensions.
     
  6. OP
    OP
    Salad Fingers

    Salad Fingers (Banned or Deleted)

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    All good suggestions guys. At this stage the idea is to have the pestal move up and down and back and forth while the motar rotates. The windscreen wiper idea would make it easy to implement the pounding and the rotation but not so easy to get the back and forth motion. I think the idea was to only use the one motor but I'll have to ask and find out other wise I reckon we're onto a winner with that suggestion.
     
  7. RussellK

    RussellK Member

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    Rather than do the back-and-forth motion of the pestle, you could instead rotate the mortar off-centre and have the pestle fixed and only moving up and down, with the down stroke sychronised so it's down when it's up against the side of the mortar.
     
  8. LeadAccelerator

    LeadAccelerator Member

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    This idea sounds a bit like an electric mixer that has the rotating bowl as well as the rotating beaters. ;) ;)
     
  9. OP
    OP
    Salad Fingers

    Salad Fingers (Banned or Deleted)

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    apparently this method is not as efficient as having the pestle move back and forth. so he says anyway.
     
  10. RussellK

    RussellK Member

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    Efficient or effective? It strikes me as being a lot easier to implement, with the only critical bit of control being the up-and-down motion, which you'd not only need to synchronise, using some kind of position sensor on the rotating mortar, but also optimise the movement to perhaps prolong or shorten the duration the pestle is in contact.

    Actually, thinking a moment longer, you'd also want the pestle to be able to pivot or rotate, depending on its angle to the mortar, so it caches and crushes the material.
     
    Last edited: May 31, 2010
  11. methodMAN

    methodMAN Member

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    high torque and cheap = windscreen wiper motors, some already have gears attached, plastic and metal variations available.

    use a DC motor controller ~$25 off ebay/jaycar for speed control.

    mM
     
  12. bonox

    bonox Member

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    gearboxes exist for a reason. You'll need one. Only question is whether you want to make it yourself or find one off the shelf.

    Motors don't run slowly. It's a function of their electrical design plus a cooling component.

    A realistic gearbox will outlast everything connected to it as long as you've appropriately sized it for shock loading.
     
  13. bonox

    bonox Member

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    Last edited: Jun 1, 2010
  14. bonox

    bonox Member

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    farnell?

    yellowpages?
     
  15. the Fan-Man

    the Fan-Man Member

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    go to a scrap yard and you will find electric motors with reduction boxes

    if that helps :S
     
  16. Goth

    Goth Grumpy Member

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    Nick the turntable drive motor (quite small, fairly low speed and relatively high torque) out of a microwave oven?
     
  17. the Fan-Man

    the Fan-Man Member

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    reduction box :)

    yes these are about 9rpm tho
     
  18. hoopstar

    hoopstar Member

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    Oatley Electronics have a range of powerful DC motors and controllers.. at fairly decent prices too..


    Hoops
     
  19. TERRA Operative

    TERRA Operative Member

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    Damper motors as used for ducted air con will probably work ok. I have two 3Nm rated motors sitting here on my desk which rotate at a tiny bit over 1 RPM (6nM motors are available easily too). The motor inside has an integral gear box and the whole motor/gearbox is about 40mm in dia. and 30mm high. Just supply it with 24V AC to set it spinning around and around and around. Two supply wires and one common, for backwards and forwards directions.
     
  20. OP
    OP
    Salad Fingers

    Salad Fingers (Banned or Deleted)

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    Thanks everyone for all the information- I've passed it on to my mate. He says thanks back.
     

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