A handy machine, especially in an emergency, is a small EDM (electrical discharge machining) setup. It will do anything from small milling jobs to burning out a broken tap. It's a nice tool to have handy when you have to make any shaped hole in hardened metals. Below are some photos of my setup which is based on a design by Robert Langlois.

On the left is the whole system including a tank for the dielectric. I use tap water doctored slightly with a portion of permanent antifreeze for a wetting agent. The fluid is directed to the electrode through a small hose and just drips as adjusted to keep the debris off of the work.

In the center is the head including the stepper motor and limit switches etc. This is a totally portable unit which makes it quite handy.

On the right is a close up view of the controller. The box on top contains the capacitors and light bulb socket and lamp. The bottom, made from the original printer box, contains the transformers and logic ciruitry. It is the main control center for the machine.