This is simple enough. I have some small micro switches with levers that will work as a last resort. However, one of our members has provided us with some very cool Turck, miniature, normally-closed, pnp output inductive sensors. These are very cool sensors and even have a small yellow LED that lights in the sensor indicating the switch is open. Inductive sensors are really ideal because they are wear-free. I really want to use them but making them work with my Breakout board is not as simple as the microswitches and might not be worth the effort in the long run.
They have a sense distance of 2cm and work with any ferrous object. You simple supply 12-30 vdc to the brown wire, ground the blue wire and black wire is the output (load). One method would be to use optoisolator to take the 12v input from the sensors and output 5v. Not sure if I need this level of complexity (no its not really that hard). I may be able to use solid state relays as well. If you have any ideas, let me know..
The breakout board (BOB board) is the interface board between the host computer and the stepper motor drivers. The board I'm using is here. It takes the parallel port connection from the host computer and breaks out the individual i/o pins and routes them to the drivers, relays, and limit switches.
The recommended configuration for the limit switches and e-stop are as follows: