This "max" configuration is for Chris Radek's tabletop mini mill.

The mill is a simple step/dir stepper system with three axes, Z
being a different scale.  There is a spindle encoder (currently
simulated) to allow threading and (maybe someday) rigid tapping.

There is basic spindle control (on/off, one direction only) and
the machine-on state enables the stepper drive choppers.
