Re: [CAD_CAM_EDM_DRO] Frozen stepper motor shaft

I don't intend to dispute, just to clarify in my
own mind.

When I use oz-in to calculate my torque from my
stepper I multiply? This seems in reverse to me.
I'm planning on using a 640 oz-in stepper. Now my
gearing from this stepper is a via timing belt.
So.. the pulley attached to my stepper is 1.910
Pitch Dia. so the ARM of this pully would be the
radius at which the belt is located or: 1.910/2
=0.955" So if I have a 640 oz-in stepper this
would equate to 640*0.955"=611.2 oz force at that
arm distance? So if instead I was to put my
larger pulley on the stepper [ this wouldn't work
because I'm trying to gear down but for sake of
discussion]it's a 3.820 Pitch Dia. so...
3.820/2=1.91" arm then we put this into this same
formulat 640 oz-in * 1.91"=1222.4 oz force. It
would seem that this is exactly backwards to how
it works, we all go get a long[er] pipe to put on
a wrench to get more ARM distance and get more
torque at the bolt. If this is infact the correct
way to calculate this stuff then I've not been
doing my calulations all wrong and my system
isn't going to budge when I go to run it.

Anyway in my mind this oz-in thing should involve
division. 640 oz-in means there is 640 oz of
force located at 1" from the center of the stepper
shaft. I don't think anyone disputes this. If the
arm was 1/2" then 640 oz-in/ 0.50"= 1280 oz force
you'd cross off the inch's because it's inches
divided by inches and you'd be left with only
'oz' unit's. If you multiplied this equation you'd
be left with oz-in^2. or at least this is how I
see it.

Help!
Jarrett

> Alan:
>
> Yes, I have brought it up before. Some will say
> I am too picky(I guess
> you are one of them) but it is NOT a division,
> it is a multiplication,
> that becomes the "unit". If you look into WHY we
> use "ounce inches" or
> similar terms for torque, you will quickly
> understand why(1 oz-in of
> torque equates to a 1 ounce force at an inch
> from the center of
> rotation, but to only 1/2 ounce of force at 2
> inches from the center of
> rotation-do the math-you MULTIPLY the ounce by
> the inches).
>
> If you ever start trying to use these units in a
> mathematical
> formula(which is not that far out a proposition,
> considering we are
> attempting to design and build machines that use
> torque) you will get
> hopelessly confused, as the units won't "cancel"
> properly.
>
> The worst part is, that the folks who KNOW it is
> "ounce-inches", and not
> "ounces per inch", and can shrug off the
> improper use, won't get caught,
> because they KNOW how to use the formulas and
> calculations. But those
> who DON'T know the proper terminology are the
> ones who most likely won't
> be able to make sense out of it.
>
> That's why I think it is important, and will
> keep bringing it up, as
> long as I think it is important.
>
> Back to the subject at hand, I think your advice
> to do an ohmmeter check
> on the windings was good, as was that of the
> other poster who
> recommended making sure none of the leads were
> touching when trying to
> turn the motors. Until Mike gets back to us on
> what else he has tried, I
> don't think we can go much further in solving
> his problem, unless it
> would be to recommend that he checks the shafts
> where theey exit the
> bearings and motor case for any evidence of
> corrosion. If they are
> rusted or pitted to the point where that is what
> is causing sticking,
> theen a good penetrating oil might do the
> truick.
>
> Andy Wander
> Verrex Corporation
>
> P.S. By the way, I am sure that you know that
> just because a Google
> search turns up a bunch of mistakes, that
> doesn't make them suddenly
> become correct.