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  1. #1
    Join Date
    Nov 2004
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    57

    Holding torque?

    A stepper motor with a holding torque of 200(mNm)is aquivalent of how many oz-in

    Thanks, Marc..

  2. #2
    Join Date
    Jul 2004
    Posts
    142
    Marc,
    200 newtons is equal to 719 oz. The mNm is throwing me a little. 200 Millinewtons = .719 oz. Hope this helps.

  3. #3
    Join Date
    Jul 2004
    Posts
    142
    Opps I found it - 200 mNm = 28.3 oz/in! And that is my final answer!
    Regards,
    Glen

  4. #4
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    Jul 2004
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    142
    mNm = Milli Newton Meter ( should read mN/m or mN-m).
    Regards,
    Glen

  5. #5
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    Nov 2004
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    57
    Thanks a million man

    Marc..

  6. #6
    Join Date
    Oct 2003
    Posts
    399
    Quote Originally Posted by BigDaddyG
    mNm = Milli Newton Meter ( should read mN/m or mN-m).
    Regards,
    Glen
    Ok, you guys can tell me to shut up if you're tired of hearing this...

    Torque is the product of force and distance, so writing oz/in or N/m is wrong. (It would imply you could open a door *infinitely* fast by touching it's hinges... and I guess we all know that's not the case).

    Also, products in the metric (SI) system is not expressly written, neither with a '-' nor a '*' nor anything else. So 'mNm' is actually the correct way of writing millinewtonmeter. (Although IMO perhaps Nmm [newtonmillimeter] would be nicer...)

    Arvid

  7. #7
    Join Date
    Jan 2005
    Posts
    1880
    Quote Originally Posted by arvidb
    Ok, you guys can tell me to shut up if you're tired of hearing this...

    Torque is the product of force and distance, so writing oz/in or N/m is wrong. (It would imply you could open a door *infinitely* fast by touching it's hinges... and I guess we all know that's not the case).

    Also, products in the metric (SI) system is not expressly written, neither with a '-' nor a '*' nor anything else. So 'mNm' is actually the correct way of writing millinewtonmeter. (Although IMO perhaps Nmm [newtonmillimeter] would be nicer...)

    Arvid
    I don't remember my math from that far back but isn't the designation Oz/In refering to weight over distance moved? I know it is a torque rating but the leverage would change the end result (ie distance from the fulcrum). the closer to the fulcrum the higher the oz. to move. and the less distance. so the formula would self correct? ie the oz. would go up and the distance down? or am i missing something.
    thanks
    Michael T.
    "If you don't stand for something, chances are, you'll fall for anything!"

  8. #8
    Join Date
    Oct 2003
    Posts
    399
    I'm not very comfortable working with pounds and ounces, but think about it this way:
    You get more torque by either increasing the force or increasing the distance from the fulcrum. If you divide by the distance, the torque figure will instead *decrease* with longer distances, and reach infinity at zero distance (since you would divide by zero). In the real world, of course, you get zero torque if you apply the force directly on the fulcrum (i.e. at zero distance), and the torque increases linearly with increased distance; thus torque is proportional to both the force and the distance - or, to force and distance multiplied. (Or if you use SI units, torque equals force times distance.)

    I'm not sure what you mean by weight over distance moved... torque is force times distance. And oh, ok, weight of course refers to force of gravity of one pound - i.e. the force 1 lbf? But it's not really distance *moved*, it's simply distance from the fulcrum, and it's not "over" but "times". Hmm, maybe I'm being too picky here, english is not my native language

    Don't you americans get to learn things like this at school? The dash '-' in your units stands for product, not division.

    Arvid

  9. #9
    Join Date
    Oct 2003
    Posts
    399
    "ie the oz. would go up and the distance down"

    Yes, correct, for equal torque you would need to increase the force if the distance is reduced. But try it:

    2 "force" * 5 "distance" = 10 "torque". Increase the force and decrease the distance:
    5 "force" * 2 "distance" = 10 "torque". Torque stays the same, as you predicted.

    And with the division:

    100 "force" / 10 "distance" = 10 "torque". Again increase the force and decrease the distance:
    10 "force" / 100 "distance" = 0.1 "torque"! This is clearly not right...

    Or taken to its extremes:
    1 "force" / 0 "distance" = infinite torque.

    Arvid

  10. #10
    Join Date
    Jan 2005
    Posts
    1880
    Don't you americans get to learn things like this at school? The dash '-' in your units stands for product, not division.
    I don't beleive i made any comments on the - verses slash. but yes we do learned stuffs like dat in da schools out her.

    I believe that division by 0 is a no-no in math is it not? (damn ders dat "-" again). thus no devision by zero is possible .Butt I aint no enginerrer.
    thanks
    Michael T.
    "If you don't stand for something, chances are, you'll fall for anything!"

  11. #11
    Join Date
    Oct 2003
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    399
    Yeah, division by zero is a no-no. The result of dividing zero by zero is quite interesting:

    x/x = 1
    x^2/x = x
    x/x^2 = 1/x

    and

    lim x->0 k/x -> infinity (k > 0)

    Set x = 0 in the first three equations and you get 0/0 = 1, 0/0 = 0 and 0/0 = 1/0. The last equation instead hints that the result should reach infinity when the divisor is 0 and the dividend is not zero. So three different results depending on which "proof" you use!

    So ok, to be mathematically correct, I should have said this:

    'Or taken to its extremes:
    lim d->0 1 "force" / d "distance" -> infinite "torque".'

    Not as clear, is it?

    Arvid

  12. #12
    Join Date
    Nov 2004
    Posts
    57
    Wow, you guys are really into numbers Just reading all those post gives me a headake

    Marc..

  13. #13
    Join Date
    Apr 2005
    Posts
    16
    140oz/in =1Nm
    how I calculate torgue to motor need? mean milling machine crank/handle come motor and how much torgue must need, how calculate this?
    first need old real milling reform new stepper system.but dont know how torgue motor need.
    secon,my own cnc projekst(small)dont move y-axle, need know torgue what use thats good? 1Nm(o,95Nm) vexta 268 1,6A/5,4V not run axle.
    same x-axle too but axle run but when I but hand sledge/taple thats stopped
    thing need more torgue but how much.

  14. #14
    Join Date
    Jan 2005
    Posts
    1880
    Quote Originally Posted by arvidb
    Yeah, division by zero is a no-no. The result of dividing zero by zero is quite interesting:

    x/x = 1
    x^2/x = x
    x/x^2 = 1/x

    and

    lim x->0 k/x -> infinity (k > 0)

    Set x = 0 in the first three equations and you get 0/0 = 1, 0/0 = 0 and 0/0 = 1/0. The last equation instead hints that the result should reach infinity when the divisor is 0 and the dividend is not zero. So three different results depending on which "proof" you use!

    So ok, to be mathematically correct, I should have said this:

    'Or taken to its extremes:
    lim d->0 1 "force" / d "distance" -> infinite "torque".'

    Not as clear, is it?

    Arvid

    with a keyboard its about as clear as it gets. but I took higher math and it looks ok to me.. but after 20yrs of not using it. I just cant remember most of it.

    they say aqe brings wisdom, but I say age just makes you seam to remember enough to bull$h!t your way through things. (thats wisdom!)
    thanks
    Michael T.
    "If you don't stand for something, chances are, you'll fall for anything!"

  15. #15
    Join Date
    Aug 2004
    Posts
    2849
    Quote Originally Posted by arvidb

    lim x->0 k/x -> infinity (k > 0)

    The last equation instead hints that the result should reach infinity when the divisor is 0 and the dividend is not zero.

    Arvid
    Well I suspect that the lim k/x as x -> 0 that most people would believe that the lim is k.....not realizing that when 1>x<0 the dividend causes the divisor to grow....pick x = 1/10, 1/100, 1/1000, 1/1000000000000....K is multiplied by the inverse of x......pretty cool. :wave:

  16. #16
    Join Date
    Oct 2003
    Posts
    399
    Quote Originally Posted by miljnor
    *snip* they say aqe brings wisdom, but I say age just makes you seam to remember enough to bull$h!t your way through things. (thats wisdom!)
    *LOL*

    Quote Originally Posted by ViperTX
    Well I suspect that the lim k/x as x -> 0 that most people would believe that the lim is k.....not realizing that when 1>x<0 the dividend causes the divisor to grow....pick x = 1/10, 1/100, 1/1000, 1/1000000000000....K is multiplied by the inverse of x......pretty cool.
    Glad you like it! You got the interval wrong, however... I guess you meant '1>x>0' - i.e. x is between 0 and 1? Your x is negative (less than one and less than zero )

    Arvid

  17. #17
    Join Date
    Aug 2004
    Posts
    2849

    Cool

    Quote Originally Posted by arvidb
    *LOL*



    Glad you like it! You got the interval wrong, however... I guess you meant '1>x>0' - i.e. x is between 0 and 1? Your x is negative (less than one and less than zero )

    Arvid
    Good catch....

  18. #18
    Join Date
    Jun 2003
    Posts
    866
    I think Newton-meter as a way of expressing a product probably is appropriate for English majors, but it's a little confusing for engineers. On the other hand N/m is just nonsense in any context, unless division is called for.

  19. #19
    Join Date
    Apr 2005
    Posts
    76

    Torque,

    Torque measured in oz/in is like this; think of a drum that is 2" diameter, that means it will have a radius of 1", now wrap a string around the drum several times with the beginning end glued to the drum, now hang a weight from the free end, let's say that you can hang 50 onces on the free end before the motor will lose it's position while under power, you have a motor with 50 oz/in holding torque. If your drum was 4" dia. and you could hold 25 oz. without slipping, you would still have 50 oz/in holding torque. Back to the 2" diameter drum, if you can hang 192 ounces on the string without slipping then you have (1) ft/lb holding torque. If your drum is 24" dia. and you can hang 16 oz on the string then you have (1) ft/lb. holding torque.

    Torque will always be measured in a Radius and a weight.

  20. #20
    Join Date
    Jul 2006
    Posts
    14
    Good explanation of torque and power.

    http://en.wikipedia.org/wiki/Torque

    Janis

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