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stepper motor torque

Discussion in 'Embedded' started by wv9557, Aug 19, 2006.

  1. wv9557

    wv9557 Guest

    Any good way to estimate torque for stepper motors you can't find
    documents for (except for buying a 600 bucks torque meter. :)
     
    wv9557, Aug 19, 2006
    #1
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  2. maybe a $2 spring balance, and a lever arm ?
    -jg
     
    Jim Granville, Aug 19, 2006
    #2
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  3. Alternatives:
    1. Estimate the torque generated via an FE analysis, but you would have
    to know: cross-sections, material data, etc. Very, very theoretical
    approach.

    2. Measure, but time-consuming an expensive.

    3. Probably the most practical approach: buy a stepper-motor that comes
    along with the complete documentation.

    Regards,
    Peter.
     
    Peter Heidrich, Aug 20, 2006
    #3
  4. 1) Replace it by a stepper motor you *can* find documents for ;-)

    2) Build your own torque-meter. Since you x-posted this from a
    robotics newsgroup, I'll boldly assume you know enough about mechanics
    to pull that off. A lever arm, a counterweight and maybe some gears
    should do it. If you want to measure power instead of torque, you
    might want to consider Joule's method of measuring mechanical work in
    terms of generated heat --- or drive a dynamo.

    3) find a cheaper torque meter. Torque wrenches for car wheel nuts
    are generally a good deal cheaper than 600 bucks.
     
    Hans-Bernhard Broeker, Aug 20, 2006
    #4
  5. wv9557

    J.A. Legris Guest

    http://www.romanblack.com/stepper.htm
     
    J.A. Legris, Aug 20, 2006
    #5
  6. wv9557

    Stephen Pelc Guest

    Just as important as torque in some applications, is finding
    the upper and lower resonance frequencies. Unless this is
    spare-time job, get the documentation for the motor!

    Stephen


    --
    Stephen Pelc,
    MicroProcessor Engineering Ltd - More Real, Less Time
    133 Hill Lane, Southampton SO15 5AF, England
    tel: +44 (0)23 8063 1441, fax: +44 (0)23 8033 9691
    web: http://www.mpeforth.com - free VFX Forth downloads
     
    Stephen Pelc, Aug 21, 2006
    #6
  7. There is more than one torque of interest. There is the stall torque,
    which most of the replies to your query address, and there is running
    torque. The latter depends on the speed, generally the faster the motor
    steps, the less the torque, but also on the drive method: direct, R/L, or
    chopper drive. The drive method makes a big difference in complexity,
    cost, and efficiency as well as torque.

    John Piccirillo
     
    Harry Rosroth, Aug 25, 2006
    #7
  8. wv9557

    cs_posting Guest

    Having played around with turning a drum to mount on a NEMA 23 and
    winching a weight up and down with it, realistcally I'd have to say
    it's not worth the trouble.

    Just bolt the motor onto whatever you want to use it for and see if
    it's up to the task. If it can do it slowly but not quickly, look into
    the driver circuit. If it can't do it, buy a bigger motor. Chances
    you are will be dealing with either NEMA23 of 34 size mounts so you can
    change the motor a lot without changing what it bolts onto (off the top
    of my head, I'm going to guess you could make a mounting plate with
    bolt holes to support either size)

    Also consider using toothed timing belts. These let you have variable
    gear ratio, absorb vibration, and tolerate the kind of shaft
    misalignments you are likely to introduce in anything built without
    carefull use of precision machine tools. Of course you can also buy
    misalignment couplings...
     
    cs_posting, Aug 25, 2006
    #8
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