Indexer

Hello,
I'm new the post and have been learning quite a bit, although sometimes with
tears in my eyes as I realize how woefully ignorant I am about electronics.I
do mechanical design,manual and CNC machining for my real job.

I plan to build a CNC router for home soon, and have been watching the
chunks of info flying over my head.Trying to catch the small ones though.
Got to start some where I guess.

Right now I am designing a rifling machine for muzzle loaders, and I need to
intermittently index a shaft 120 degrees of rotation.

Does any one know of a simple method (meaning cheap and or home built) of
using a stepper motor and some type of controller that will cause the motor
to rotate 120 degrees and stop, every time a limit type switch is depressed?
Or some other method?

I also need to activate a solenoid every 3rd touch of a switch or other
electronic activating method.

Any help gratefully accepted! Thanks! Steve