I have made a bunch of little chisels out of allen wrenches lately. Man, them are the hardest things I\'ve found bar none. I was carving some brass and they cut real good AND they actually held their edge.
If you\'re going to try this it takes a little care to have it work well. Get a glass of water with a lot of ice in it and keep it with you when grinding the wrench. VERY LIGHTLY sand or grind the blue/black patina off the first inch or so till you see bright clean metal. Then as you do the heavy grinding, go in about 1/2-1 second increments and immediately cool down in the ice water....let the metal get real cold. While grinding, watch the clean bright area for COLOR. If it starts to turn color, that\'s bad. The more it changes color, the more it\'s losing it\'s temper. If you get to blue or glowing red, I think the metal\'s structure is very degraded as far as having the temper to hold a sharp edge. It does take patience to make a good sharp blade. Get it roughed out and then using graduated sharpening stones, finish it. I was actually able to get them to a razor\'s edge........and, as a bonus, they\'re cheap!!