Vanadium is the alloying element that I see in the tool steel analysis
that's somewhat unique to a wrench. I would NOT make ANY wrench out of
mild steel unless I knew that the torque was going to be very low. Just
try making a simple screwdriver from mild steel and you will see what I
mean.
I have used steels as simple as 1045, hardened and then tempered to
the red temper color, where a medium amount of torque is required.
5160 (leaf or coil spring from most cars made since about 1950) is a
good bet and there's a lot of it around, so you can try different
approaches.
The amount of room you have around the fastener also plays a big part.
If you can make the tool real hefty, it has a better chance of
surviving, obviously.

Pete Stanaitis
------------------

Bob Engelhardt wrote:
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