The Nov-Dec issue of HSM has the last in a series of 5 articles about
making a tool that _cuts_ knurls. It's an interesting tool and way
beyond my capabilities, but he makes a wrench for the knurling tool that
uses a neat technique.

The wrench is a 1/8" 6 point closed end. He takes a piece of mild steel
round stock, drills a hole that's an interference fit for a 1/8" Allen
key, presses a piece of the key in, and forges the stock to fit the key.
He counts on the hardness of the key resisting the forging. I.e.,
the stock deforms, but not the key. He now has a 1/8" hex hole in the
stock and he slices off a piece to use for the wrench. Long story
short, but you get the point, I hope.

My question is: is mild steel OK to use for a wrench? I thought
commercial wrenches were some kind of hard alloy. And I ask because I'd
like to use this technique to make some square sockets for those square
headed set screws and square nuts. (Why does anybody use square nuts?)

Thanks,
Bob