Motor Selection

Discussion in 'Servos & Animatronics' started by mitlrpro, Sep 5, 2016.

  1. mitlrpro

    mitlrpro New Elf

    Joined:
    Nov 12, 2015
    Messages:
    20
    Likes Received:
    0
    Location:
    Gosford
  2. livetoride

    livetoride Full Time Elf

    Joined:
    Jan 11, 2012
    Messages:
    145
    Likes Received:
    5
    Location:
    Ballarat
    Find Me On:
    Slightly left of field here but have you thought about a window wiper motor? They are 12V, Cheap and easy to come by and you can control how quick they move?
     
  3. djgra79

    djgra79 Senior Elf

    Joined:
    Dec 27, 2011
    Messages:
    653
    Likes Received:
    69
    Location:
    Cranbourne West
    Find Me On:
    I've bought a couple of the same motors for use with Halloween props this year. Haven't hooked them up yet but mine would only move foam boards. Not sure they could handle much load or weight of wood, but cheap enough to try I guess.
    Wiper motor would be a good bet too, or a garage door motor. I've ripped out my old garage door motor but it was too fast at 40rpm, so am getting a buck converter to reduce the voltage and therefore the rpm.
     
  4. damo1271

    damo1271 Full Time Elf Generous Elf

    Joined:
    Oct 12, 2011
    Messages:
    193
    Likes Received:
    3
    Location:
    Adelaide
    Find Me On:
    I don't think there is a simple yes or no answer to this.

    The answer is going to depend on two things.
    Firstly what is the force needed to be exerted on the moving parts (Santa arm) in order to make them move.
    Secondly what is the force that can be exerted by the motor.

    Assume the 20RPM model has the same torque as the 160RPM model (10.5kgcm) and the torque figures are accurate. The motor can therefore move a mass of 10.4KG at a radius of 1cm.
    Unfortunately it is not then as simple as weighing santa's arm. :(

    You also have to consider how much vertical movement the santa arm is going to require. More movement means a wider radius at the motor and therefore less mass that can be moved. The attachment distance between the pivot and the motor linkage will also affect the torque you need in conjunction with the prior factor. Both of these factors can be offset somewhat with counter weights on santa's arm.

    A wiper motor can probably be bought for the same price from the local car wrecker and would have superior torque. Ive seen them used on all sorts of things from winches to rotisserie units.
     
  5. Skunberg

    Skunberg Full Time Elf

    Joined:
    Jul 10, 2010
    Messages:
    194
    Likes Received:
    0
    Location:
    Eagan
    Seen wiper motors use for 1/4 and 3/8 inch plywood for a arm or train wheel. You can use simple pulleys to convert the RPM as required. Or even rod linkage can effect rpm. Lot's of options to sort through.
     
  6. scamper

    scamper Senior Elf

    Joined:
    Jan 5, 2014
    Messages:
    737
    Likes Received:
    40
    Location:
    collie
    Find Me On:
    Here is one completely out of left field. microwave turntable motor!
    They are slow and very high torque.
    They do vary in speed and voltage, so you will need to double check. But lots of people throw away microwaves, so rip it out and have a look. It is usually written on the motor what the specs are.
    Otherwise, yes, I would go to a wrecker and get a wiper motor.
    that is if I didn't have a motor out of a 12v toy scooter already 8)
     
  7. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

    Joined:
    Apr 26, 2010
    Messages:
    6,471
    Likes Received:
    16
    Location:
    Albion Park NSW
    Find Me On:
    Yes a car wiper motor works well for this application, have seen others use this before with great results and can be bought cheaply from a wreckers, has high torque, and safe 12vdc, pretty much what the others are saying
     
  8. OP
    OP
    mitlrpro

    mitlrpro New Elf

    Joined:
    Nov 12, 2015
    Messages:
    20
    Likes Received:
    0
    Location:
    Gosford
    Thanks for all your answers....looks like a trip to the local wrecker and some trial and error.
     
  9. JPB

    JPB Full Time Elf

    Joined:
    May 13, 2010
    Messages:
    304
    Likes Received:
    0
    Location:
    Glenwood
    I have used a microwave turntable motor in the past to fix a wire frame deer with a nodding head. On a wire frame you cant hide a large motor so the microwave motor was perfect.
     
  10. OP
    OP
    mitlrpro

    mitlrpro New Elf

    Joined:
    Nov 12, 2015
    Messages:
    20
    Likes Received:
    0
    Location:
    Gosford

    Have you hooked yours up to your Halloween props yet? I'm thinking of the corflute route now...
     
  11. Fing

    Fing Full Time Elf Generous Elf

    Joined:
    Dec 31, 2014
    Messages:
    349
    Likes Received:
    29
    Location:
    Muswellbrook
    Find Me On:
    Jaycar sell some geared motors, used one recently on another project and seemed to have plenty of Torque. Bit smaller than a wiper motor
    of course your milage will vary....
    Cheers
    Fing
     
  12. djgra79

    djgra79 Senior Elf

    Joined:
    Dec 27, 2011
    Messages:
    653
    Likes Received:
    69
    Location:
    Cranbourne West
    Find Me On:

    Not as yet as I'm waiting on a replacement (one was DOA) and I'm also waiting on some cam arms for them.
    That and I haven't cut out the foam board yet :)
     
  13. OldMarty

    OldMarty New Elf

    Joined:
    Dec 27, 2016
    Messages:
    7
    Likes Received:
    0
    Location:
    Melbourne, East Suburbs
    Yep! Windscreen wiper motors are awesome, they are strong, heaps of torque, only need 12volts and are cheap at most car wreckers ;-)

    I use them everywhere, and in many cases i also use microswitches to set the end limits (depending on the props).

    ;-)
     

Share This Page