Hi TP,
I have had a tweak of my DC controller and can drop the speed down to 20rpm. I then measured the arc of detection of the spindle proximity switch and got about 13 degrees.
Considering 20rpm/60 = 0.33r/s or 3sec/rev, and 360/13 = 27, then 3/27 = 0.11seconds the switch is active. Is that sufficient for a reliable trigger?
I suppose we could also set a timer cycle at the same time so if it doesn't detect in, say, 5 revs bail out of the toolchange program and call an alarm.
To comment on your last post. The spindle is controlled by PWM and will run a steady 20rpm now I have tweaked the pot, but currently I don't have a seperate relay to reverse the spindle. I only have to get close, however, as don't forget the spindle will centre when the pnematic ram operates if it is +/- 20 degrees or so from perfect alignment
...Sweep