Drilling thin sheet metal

[Stephen]

There is an rpm lower limit in Mach4. Some people have lowered it to get the RapidChange ATC working. See here:

RapidChange ATC: ATC for ER20 (and other) spindles

Check the machine.ini file for spindle min rpm limits. It was a long time ago, but I think I had to change a variable in there when I originally lowered the speed range on mine. I know for that old spindle and VFD I didn’t have to change any VFD parameters.

The spindle will lose torque at lower rpm, but it should still work fine for small diameter bits.