Drill bits are a mystery to many people. However, the link below should provide a good idea what this world is all about to some extent. Grinding your own drill is actually a good way to go if you are into a little patience, and have a drill angle that you can use to put the drill against, and check out the angles, and amounts off each side you cut.
There are several hand grinding examples available on line that you can check out for your self if you wish-good to go through a few of these sites to reinforce safety procedures. Hopefully, you have used a grinding wheel before that is anchored to a table-work bench, and are careful about wearing some eye protection-be careful of the heat generated to the drill, it gets very hot-Ouch! Keep some water next to your work, to dip the drill into when it gets hot to cool off-don't worry about temper loss-just be careful. If you have not used a grinding wheel before, have a pro help, and teach you-grinding wheels spinning about the room are not very healthy, nor inhaling dust from the wheel with out a vent duct collector handy.
http://en.wikipedia.org/wiki/Drill_bit