RE: Low cost Servo Controller

At 07:41 PM 9/13/1999 , you wrote:

>From: David Howland <dhowland@...>
>
>Jon, Thanks for your feedback. You asked why anyone might want to apply

servo motors to software which supplies step and direction signals, rather
than obtain existing controllers and motors for one or the other? First
of all, so far, no one has set me straight on the EMC (or other) drivers
for servo or stepper controllers. Such information will be helpful. It
may bring to light many facts concerning this.

>

David,

EMC will run either servos or steppers. Jon and Matt can give you the
details on the servos, because it was written for servos in the first place
and I believe they were the original beta testers on it. The rest of us,
who run stepper systems currently, bugged the crap out of Fred Proctor to
make it run steppers too. He did and now he has several dozen beta
testers. I have been running steppers for several years now and want to
move on to servos. My side business is picking up and I need the speed.

Running a CNC without ballscrews can be done- but you have to be careful.
I did it for a couple of months, right after setting up the mill, but
switched to ballscrews ASAP. Pulling the table around with .030" backlash
was no fun. It was just like machining by hand, except I had to really
watch it because the cutter could pull the workpiece into itself. Couple
that with losing some steps and you're in real trouble.

Dan Mauch and Bill Wainwright are running a hybrid step & direction/ servo
motor system and Dan is able to get 130 ipm rapids on a mill/drill. That
seems pretty good to me for a system that all together costs around $1200.
He's running Clifton Precision motors from "The Surplus Center" of Nebraska
($20 ea) and using Maxnc as the control software on a 486 DX/66.
I agree that the STG card is really the ultimate way to go, but I want to
set up multiple machines in my shop and don't want to spend $800 for each
PC control- right now. Maybe later. Of course, maybe Dan and Bill will
come up with their own control card by then too.

Dan Falck