R
Rich Grise
- Jan 1, 1970
- 0
My office opens onto a machine shop. I was just now chatting up the
machinist, and idly musing on the workings of the transport mech or
whatever it's called - it's got motors to drive the bed in X and Y.
This is a Bridgeport end mill, with electric motors to slew the bed.
And I was wondering about turning it with a stepper motor - with
the gear ratio, it looks like you could get about .0005" per step.
"Hmmm ..." I mused to myself, and the machinist (Jimmy) was talking
about closed loop and open loop and the accuracy of servos because
they use the sine and cosine, and that a stepper motor can miss a
step, and so the feedback comes up. "How does the controller know
if you've missed a step?" And I start thinking about position
sensing, and asking about where's the best place to put a pot,
and he says, "Well, you could just use the readout." I slaps
meself in the haid - "Boy! Am I Stupid!" "What? For not thinking
of that right away?" "No. For slapping myself in the head like
that. That really hurt!" And I went, That's trivial. I've written
stepper motor controllers in Z80. You can get a driver for a few
bucks. And I have not only THREE computers (I inherited the one
that they replaced in the front office), but an M68ICS05P in-circuit
simulator/development system in my office.
I'm gonna _BEG_ the boss to let me do that. (slap together a
68HC705P6A and a stepper motor driver, hack into his Bridgeport,
and have NC on a beer budget!)
Wish me luck!
If I get the project, I promise to make frequent progress reports,
so everybody think good thoughts!
Cheers!
Rich
machinist, and idly musing on the workings of the transport mech or
whatever it's called - it's got motors to drive the bed in X and Y.
This is a Bridgeport end mill, with electric motors to slew the bed.
And I was wondering about turning it with a stepper motor - with
the gear ratio, it looks like you could get about .0005" per step.
"Hmmm ..." I mused to myself, and the machinist (Jimmy) was talking
about closed loop and open loop and the accuracy of servos because
they use the sine and cosine, and that a stepper motor can miss a
step, and so the feedback comes up. "How does the controller know
if you've missed a step?" And I start thinking about position
sensing, and asking about where's the best place to put a pot,
and he says, "Well, you could just use the readout." I slaps
meself in the haid - "Boy! Am I Stupid!" "What? For not thinking
of that right away?" "No. For slapping myself in the head like
that. That really hurt!" And I went, That's trivial. I've written
stepper motor controllers in Z80. You can get a driver for a few
bucks. And I have not only THREE computers (I inherited the one
that they replaced in the front office), but an M68ICS05P in-circuit
simulator/development system in my office.
I'm gonna _BEG_ the boss to let me do that. (slap together a
68HC705P6A and a stepper motor driver, hack into his Bridgeport,
and have NC on a beer budget!)
Wish me luck!
If I get the project, I promise to make frequent progress reports,
so everybody think good thoughts!
Cheers!
Rich