In the past, we've used one of those cast iron hand grinders with the metal plates, but you can't really get a fine flour from one of those. This year we bought an electric grinder that uses grinding stones, you can grind wheat into flour with it, so it should make nice corn flour also.
The corn is a variety from Montana called Painted Mountain. It's supposed to grow at higher altitudes up to about 6000 feet. We're not nearly that high, but it's also a pretty tough short season corn.