Re: simple stepper power question.

Alan,

Spring scales share a bit with our machines...

Most are pretty repeatable, but NOT very accurate.

If you can find a repeatable one, you can calibrate it into accuracy.
Which means using weights to reset the scale to what it REALLY is
registering. Do this, and most any scale will work. HF sells one, and
most sporting goods stores will have 'em.

Hope this helps,

Ballendo

--- In CAD_CAM_EDM_DRO@y..., Alan Marconett KM6VV <KM6VV@a...> wrote:
> Hi Dan,
>
> That sounds like a good system. I haven't seen good spring scales
> around, 'tho. Where did you find yours?
>
> Also, I recall that Mariss posted a schematic of a Dynamometer
circuit a
> while back. It's under "circuits" in the files section.
>
>
http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/CIRCUITS/DYNOMOMET
ER%20CIRCUIT.pdf
>
> I've been wanting to try this approach to motor testing.
>
> Alan KM6VV
>
> Dan Mauch wrote:
> >
> > When I first got started in cnc and step motor driver kits,I
looked at
> > ways to measure the torque of various motors and the performance
of
> > various drivers at various output voltage. I heard of using a
weight
> > with a pulley on the motor and figured that was too crude.
> > So I designed my own and machined a flanged pulley for the
stepper motor
> > to a radius of .967 and that added to one half of the thickness
of my
> > nylon cord equaled 1.00" radius so my readings would be in oz
inches. I
> > made a motor mount and then using a deadhead on one side I
attached a
> > spring scale. With the motor running at the speed I wanted, it(the
> > pulley)performs like a capstan. When the cord is slack, it slips
and no
> > torque is noted. As I pull (I have a spring scale on this side to
> > measure this pull also)on the other end of the cord that is
wrapped
> > several times around the pulley which has a spring scale, I note
the
> > reading on the spring scale. I set up a matrix and recorded the
torque
> > and the current for each speed I wanted to measure. There's a bit
more
> > to it but is much more controllable than other methods and it got
the
> > measurements that I wanted.
> > Dan
> >
> > -----Original Message-----
> > From: dave_ace_me [mailto:davemucha@j...]
> > Sent: Thursday, April 18, 2002 5:07 AM
> > To: CAD_CAM_EDM_DRO@y...
> > Subject: [CAD_CAM_EDM_DRO] simple stepper power question.
> >
> > is there a formula to determine power of a stepper ?
> >
> > I have a Slo-Syn NEMA 34, 1.7 volt, 4.5 amp
> > single stack.
> >
> > Also, has anyone put together a simple test
> > for stepper power ? Seems like a weight,
> > and a long crank arm with holes drilled
> > each inch would allow one to keep moving
> > the wieght farther out until the motor
> > started missing steps.
> >
> > Dave