I finally got back to the Emco project after a few years. Squirrel! I had thrown it together trying out some pwm drives I had – which seem to work great. When I started pllaying with the spindle I started getting noise. (sporadic estop pulses). (mainly because in my excitement of the servos working well – I didn't pay much attention to grounds..)

So – Taking the time to do it right.. (I want a little lathe to test the polygon turning..)

Currently the servos are tuned with a max following error of .00007", acceleration of 40in/sec^2 and top speed of 150ipm. Very happy with this – and it looks like I could up the acceleration.

addendum… There was a setting in the ini file that was capping the acceleration at 6in/sec^2.. No wonder why it looked so good. So – upping the acceleration to 50in/s^2 I get a peak following error of .0002" (10 encoder counts – which is exactly what I would expect) Now it feels as expected – accelerating to 150ipm is pretty instant.

sam

Yes – some Pitmann servos that came with 500 line encoders. I am using Mesa interface hardware that does the high speed pwm and encoder counting. (5i25) which acts like 2 super high speed printer ports. (expandable – you can get daughter boards that do all kinds of cool stuff – analog servos, steppers and such)

I am using it in kinda unconventional way (think cheap a$$) (mesa + cheap bob)

some machining required…

more close up action…

That was all by hand gcode. The actual polygon turning is currently done by sending info to hal layer from gcode.. I hope to do a remap but I am not there yet. So something like (this is on the mill – polygon boring)

(polygon radius)
m68e0q.30625
(number of sides)
m68e1q6
(Cutter diameter – probably get from the tool table in the future)
m68e2q.375
(rotate poly 0deg)
m68e3q0

(enable polygon component)
m64p0

(disable polygon component)

m65p0