Re: My stepper getting hotter

Mariss:

Thanks for the data - I had no idea my curiosity would lead to
you doing all that work! About the data, I am not clear exactly
which variables are measured and which are calculated. I know
that all of the "Amps" curves are measured data. "Stalled" and
"No Load" amps are self evident. I think "Maximum Load Amps" is
the power supply current when the motor is loaded just short of
stalling or losing steps, right? And "Motor dissipation watts"
is calculated, "No Load Amps" times Voltage? The one I'm not sure
about is "Motor Power Output". Is that a calculated result (as
the text seems to indicate), or the shaft power as measured by
the dyne (torque times speed)? How do you acquire the data - you
don't happen to have it in a spreadsheet do you?

The part about motor losses being independent of speed is hard
for me to get through my head. I'm programmed to think of motor
current increasing with load, since both DC and AC motors work
that way. I'll "get it" sooner or later.

I realize that my questions go far beyond what is needed to
simply use Gecko drives and steppers on a CNC machine - perhaps
we should take this off the list, or perhaps I'm simply being
annoying, and I should drop it and let you get back to work.
If you want to go off list, or drop it, you can contact me
at jmkasunich "at" ra.rockwell.com (work email, read daily) or
jekasunich "at" worldnet.att.net (home email, read every couple
of days, depending on how busy I am).

This thread has gotten me curious enough about stepper motor
speed/torque/current/efficiency relationships that I'm trying
to figure out how to make a stepper sized dyne cheaply in the
basement! I've got a lot of salvaged steppers, ranging from
tincans and NEMA 17 to NEMA 34, many with no data. It would
be nice to be able to characterize them. The Shoptask project
wants NEMA 34 at 300 oz-in or more, microstepped. I am also
thinking about a robotics project that would need many (18+)
smaller motors. That project might use the steppers from 5-1/4"
floppy drives. Cheap motors, with (cheap) unipolar drive.
Eighteen Geckos would be nice - but too steep for my budget.

Regards,

John Kasunich

--- In CAD_CAM_EDM_DRO@y..., "mariss92705" <mariss92705@y...> wrote:
> John,
>
> I posted "Loss and Power vs Voltage.pdf" in the Files section,
> Circuits folder. This is the preliminary result from all
> the "science" I have been doing.
>
> Mariss
>