Re: [CAD_CAM_EDM_DRO] Re: Volt and amp ratings for surplus steppers

Roy and Dave, thanks for the replies! After I wrote that message, I read
further back in the archives, and found reference to using 3 to 25 times the
voltage to drive a stepper, and now your information helps it make sense.
Are choppers configured to turn off at a preset current?

I Googled Roman Black and found a copy of his web page explaining basic
torque measurements, so I have a next "step" <bad pun, but I can't help it>
for some of my parts. Thanks for that reference.

Even though I am planning on doing lost foam casting, it had not occurred to
me to use small steppers for a foam router. What a truly useful tool that
would be!

Still, I can't figure out a use for that half inch diameter by inch long
"minature" stepper - so maybe it will become a desk ornament. Or I may find
someone into minature robotics that wants it, or... Maybe a lost wax carver
for jewelry? I could move the wax, and keep the router stationary.

This sure opens up a whole new universe to dream in, doesn't it?

Back to lurk mode, while I read enough to ask smarter questions,
rexarino

Roy wrote:
A higher current won't happen right off when you apply a higher voltage,
that's the nature of inductance, that there's a lag time involved. In fact
that lag happens when you apply any voltage, and the whole point of using a
higher voltage is to get the current up to the level you want quicker. And
then you cut the voltage off. That's what chopper drives are all about.
Otherwise if you just applied a higher voltage and then let the current
continue to rise you'd burn the motor out.

<snip>

> Hi Rex,
>
> A stepper has some basic numbers. volts amps, resistance and you can
> run the motors using those numbers.
>
> however, if you can pulse a higher voltage while watching the current,
> you can make the motor run much faster.
>
> the idea is that if you have a 12 volt motor at 1 amp, and feed it 60
> volts, that 1 amp will get there about 5 times faster. of course, if
> you watch the amps, you clip the amps once they hit the motor rating.
> that way, you don't over amp the motor and burn it up.
>
> Since you need a driver that chops the amperage, they call those
> drivers choppers.
>
> As for the "too small for cnc" you can make small machines that will
> do real work. small wood or plastic or foam or many other uses.
>
> Dave
>
>
> --

There is only one basic human right, the right to do as you damn well
please. And with it comes the only basic human duty, the duty to take the
consequences. P.J. O'Rourke


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