On Sat, 19 Jul 2003 11:46:41 -0700, Brian Pitt <
bfp@...> wrote:
> if it is anything like the one I tore into the "encoders" may surprise
> you
> on that one they were an odd type with raised spiral magnetic arms
> spinning over opposite spiraling traces on the pickup board with a
> daughter card to convert the signals nothing like the slotted disk
> optical encoders I was expecting
>
> you might be able to use the motors with the original main board and
> build a stronger gantry to hold the drill rig ,HP claims a resolution of
> 1/40th mm on those plotters but the motors aren't any bigger than they
> need to be to move the original parts (paper and pen holder)
> maybe if you use a belt reduction to get more torque and scale up
> the HPGL output to get it back to the right size?
>
>
> Brian
but maybe then it is much easier to use one of the free designs on the web,
which use steppers.
some use very simple stepper controller circuits on lpt.
if interested in stepper control please read "control of stepping motors,
david jones, university of
iowa, dept. of computer science." this document you can easily find with
google.
i like it. shows control circuit optins and also copes "how to increase
performance/speed" issue...
but i like the 7475a plotters and i would keep one if you can interface it.
you can use it for other things (like plotting aerofoil shapes for making
foam wings for rc plane).
it is also one of the old good things from hp, before they changed from
"product orientated" to "consumer orientated".
before charly came etc..
i don't believe this servos can be run at 20000rpm or so. so use as i
spindle is not good i think.+
regards
stefan