I have a Harbor freight mini mill with the dumbest possible spindle control. The mill comes from the factory with a variable resistor to control speed. My idea was to connect a variable resistor to a $5 model airplane servo. So the PWM output from LinuxCNC drives the servo and the servo turns the pot which controls the spindle motor. I would never be able to do rigid tapping with this setup.
I just bought a generic 600 line per revolution optical encoder on eBay I intend to use this to measure spindle RPM. My plan is to use one of those new $4 Raspberry Pi "Pico" boards to read the encoder. The little microcontroller can encode data line crossing at over 1MHz. I plan to send the data back to LinuxCNC. Then in phase 2, I will put the PID control loop inside the Pico. Then over time move other functions like limit and home switch interfacing into the Pico. This will reduce the wires as the pico can be mounted directly to the mill and housed in a little plastic box But today the spindle is open loop with no RPM sensor and a model airplane servo turns the knob for me. Anyone wanting to do real-time control for way-cheap needs to look at the Raspberry Pi Pico. They cost $4 each and have two ARM M0 cores and also the "PIO" system which is basically 8 very simple and fast "cores" that have direct access to IO pins and run independently of the two CPU cores. Oh, and the entire thing can be programmed in Python if you like. Or you can use the Arduino IDC, It is very easy for beginners. On Sun, Jun 13, 2021 at 12:52 PM John Dammeyer <jo...@autoartisans.com> wrote: > Quick little survey on what everyone has on their machine for spindle > control. > > 1. Do you have a VFD on a 3 phase motor for Lathe or Mill. > > 2. Does the CNC controller drive the spindle or do you set the speed and > ON/OFF manually? > > Just curious > John > > > > "ELS! Nothing else works as well for your Lathe" > Automation Artisans Inc. > www dot autoartisans dot com > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
