I couldn't expand on my old thread now that they're read only, but here's pics of the hall effect switch / pneumatic solenoid auto driller supplement I was prototyping a couple weeks ago.
Worked fantastic. Big thanks to everyone who helped me, especially grumpy mike on the code end.
I have to build (2) more of these, and I'll use a better box, etch circuit board, etc.
Once again, thanks everyone for the help. This is the first Arduino project I've done that I've actually used to control something on one of my rigs...it was so cool to see it in action.