RE: [CAD_CAM_EDM_DRO] CNC on the cheap

HI Richard,

Try to get the schematic and study it. Find out what and where the drivers
are for the stepper (probably) motors. Little steppers are often driven
4-phase, so you'll probably have to send them 4-phase signals. A stepper
driver chip, if it can be identified, can link you to the data sheet for the
part, from which you can decide how to interface to the driver chip.

TurboCNC can generate 4-phase signals for several stepper motors. If the
chips require step/dir, then so much the better!

If you can't decipher the drivers, then just use the steppers. One of the
kits that might be able to drive the steppers is the K179 kit made by
KitsRus. (Read recently posted message from Dan Pines on the Sherline
list).

http://www.electronics123.com/s.nl?sc=14&search=k179

If you're REALLY good, identify and reprogram the CPU in the printer to
accept YOUR commands and drive the stepper motors accordingly!

Alan KM6VV

>
> Greetings. I've just joined the group and have an idea that I'd like
> to get out there.
> I've gotten hold of an old dot-matrix printer that still works (From
> Digital Corp.) As is my usual practice, I took it apart to see what's
> going on inside, then it occured to me that there is everything there
> that's in a "real" CNC: X and Y axes,and another siginal that could be
> tapped off to function as a Z axis.
> I know (mechanicaly) that I could fashion an itty-biddy XYZ device as
> a test bed to learn with as I save for a REAL CNC.
> Obviously, I know this would have virtualy ZERO "oomph", Mostly it
> would be a platform for learning basic control of a machine. Maybe It
> would have enough juice to cut foam or (at best) balsa.
> It is the programing/control of the thing that's a mistery to me. I
> know the thing works as a printer, 'cause I hooked it up (both before
> and after dis-assembly) and it works. It's just a matter of figuring
> out how to talk to it.
> Any ideas on this?? I'd love to hear what you-all have to say!
> Thanks,
> Richard
>