On 11/21/21 9:24 PM, John Dammeyer wrote:
I'm running my AC Servo spindle motor as step/dir and can easily tell LCNC to
do 1 RPM. I also have the quadrature encoder on it so I can do power tapping.
The drive is through the MESA 7i92H as one of the stepper channels as is the
encoder signals.
Is there a way to tell the spindle to turn until it finds the index and stop so it's always stopping at the exact same spot? Like decelerate to 0.5 rev per second (30 RPM) or slower and stop when the index happens? With either an M5 or the button on the user interface?
I currently have acceleration/deceleration set high so it reverses quickly with power tapping. Not to mention the ratio from motor to spindle isn't quite 1:1 because I didn't turn the pulleys exactly the same diameter or groove depth. But on an M5 a deceleration to 30 RPM and then a complete stop on the index edge.
Thanks
John
Some of the '80 vintage Mazaks used a hydraulic cam to index the
spindle. Fast and positive.
Stop the spindle, rotate with cam which locks orientation for tool
change, change tool, get the cam clear of the drive pin, start spindle.
If I were doing that today I would use 3 sensors. IOW a guard sensor
either side of index, rotate quickly to detection of guard slow way down
and search for the central sensor. How you know which is the shortest
path is left as an exercise for the "student". ;-) Or maybe one simply
defaults to searching in one direction.
If you don't need orientation then a stepper motor and a gear would seem
to be as simplistic as one can get.
Dave
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