If you can't find any information from the manufacturer (via
manufacturer, part numbers, or even specs from the disk drive it came
out of), I recommend taking it apart and having a look at the guts of
the motor.  Not only will you be able to figure out some of these
parameters, but you'll learn how stepper motors function if you don't
already know.  In combination with a good resource like the following:

http://www.cs.uiowa.edu/~jones/step/index.html

you'll have a good handle on what is going on.  That particular
collection has more information than you probably want to know (I
haven't read through very much of it myself), but it has quite a few
links to other sources from which you will quickly learn the basics.  I
believe there might even be a link to a site on reverse engineering
these things.

With all that in mind, once you open your patient up, you can determine
how many phases the stepper has and how to command them (although you
can determine the number from the number of input leads, but I don't
think you can determine how to control more than 2 phases short of
experimentation).  You can also determine the step angle by the number
of teeth on the rotor.  I'm not sure how you would determine the working
voltage/max speed ... I believe they can operate over quite a range, but
the current is usually limited by the winding resistance and/or gauge of
the windings (I've seen 30 gauge which will handle something like 1A).

This certainly isn't the quick and dirty method, but I hope this helps
get you started.

- Dave

Joan Ilari wrote:

> I have a stepper motor salvaged from an old disk drive and
> I would like to know its main features in order to use it
> in my projects (working voltage, max current, step angle,
> max speed, etc...).
>
> Is there some way of getting these parameters (experimentally
> or through some kind of disk database ?). The motor has no
> id number.
>
> Thanks
>
> --------------------------------------------------------------
>      Joan Ilari                 joan.ilari@terra.es
>      Barcelona                  Voice:  +34 93 431 96 39
>      Spain
>
> "I've seen things you people wouldn't believe. Attack ships on
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>  the dark near the Tannhauser gate. All those moments will be
>  lost in time, like tears in rain. Time to die..."
>                                                -Blade Runner-
> ---------------------------------------------------------------
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