Typical Arduino UNO Rev3 with the ATMega328p AVR. Flashed with GRBL 0.7 since I am using the ULN2003a transistor arrays. Maybe down the road I’ll get some easy driver motor controllers and use a updated version of GRBL. 7414 Hex Schmitt-Trigger to produce a PWM signal to drive the spindle. I was going to use a 4016/4066 to use as a switch between the Arduino and 7414 but the two chips I have are not working so I might use a TIP122 power transistor or maybe another unused spot on a ULN2003a since three chips are used any only four I/O are used per-chip. However the 7414 needs 5 volts to run so I might have to use the TIP122.
In all I’m still working out the kinks and issues to turn this theory into fact. Yes I can go buy a CNC shield and drivers but I prefer to use what I already have.