Levels of sophistication, was Re: Re: Re: Re: etc.

At 03:33 AM 10/14/00 -0700, Brian wrote:

>are we still talking about running plain old stepper motors
>or are we going to treat them as some kind of hybrid mega-pole
>sub-micro stepping brushless servo motor with poly-phase
>sine wave external amplifier driver boards now?

I can empathize with what Brian is saying. My "day job" is mechanical
engineer working for a laboratory equipment manufacturer. The project I'm
on involves a stepper-driven X-Y mechanism. The electronics and firmware
guys are microstepping the size 17 steppers (200 step/rev) with what is
basically a digitally-generated tweaked sine wave from a set of lookup
tables. The steppers are not much more than synchronous motors at that
point.

But at home, I have the (almost stereotypical) Sherline milling machine
which I'm converting to CNC for my own hobby use. I've got an ancient
"lunchbox" (luggable PC with VGA plasma display) into which I've stuffed a
"trickle-down" 486-66 motherboard and other guts. It will live out in the
garage and be dedicated to driving the Sherline. Right now, it's running
DR-DOS, and I certainly don't want to install Windows on it unless I'm
backed into a corner...

I won't care if what would take the prototype shop guys at work 10 minutes
to do on one of the Hurco mills, takes all night with my little machine.
If I need to nibble away with .020" cuts, fine. As others have said, if I
can use the Sherline as a springboard to larger stuff, fine. But for what
I do (masters for N scale model railroad equipment that gets cast in RTV
molds) the working envelope of the Sherline is perfectly adequate. It
sounds like one of the half-stepping controllers will do well for this use.

I appreciate the whole realm of discussion on this list. All of it is
informative, even though all isn't relevant to my current situation...

Best regards,

Randy

Randy Gordon-Gilmore ,----.___________ ______________ _________________
ProtoTrains // = = === == || == == == = || == == == = == =|
Rio Vista, CA, USA /-O==O------------o==o------------o==o-----------o==o-'
zephyrus@... http://www.rickadee.net/~zephyrus