Tim Wescott wrote:
On Thu, 08 Aug 2013 11:40:27 -0400, Ed Huntress wrote:

On Thu, 8 Aug 2013 08:12:16 -0700 (PDT), Bob La Londe
wrote:

I am sure you are familiar with them. The flat black (sometimes
otherwise coated) wrenches that come with a lot of power tools for
changing blades, bits, discs, etc. They look like they are stamped out
of sheet. I am certainly not going to make a stamping die for one
wrench, but I am sure I could cut one out of flat stock on the mill when
I need one and a regular mechanics wrench won't fit. The thing is I
don't know what steel to use.

How about an inexpensive alloy that might be easily heat treatable. I
don't think surface hardening would help for a wrench or a spanner as
the cross section would still be softer, but maybe somebody who knows
better could speak up?

Those things are almost always made of plain carbon steel. 1070 is
common for tools and other odds and ends that need strength with a
moderate amount of ductility.

You'd be suprised how *few* things that we think of as high-strength are
actually made from alloy steels. For example, the piston rods on shock
absorbers and struts: Plain carbon, 1070.

Quality wrenches often are made from a proprietary grade of
chrome-vanadium alloy. But the advantage in most practical uses is
slight.

That depends on what you see as "practical use". If it says "chrome
vanadium steel" on the outside, and that makes the wrench sell more
without you getting sued for false advertisement, isn't that a highly
practical use from the "let's make lots of money" point of view?

I've seen some pretty dubious tools with markings like this.

finish quality is a pretty good sign of what you're dealing with. If the
nickel plating is flaking off and the thing has never been used, you can
bet the rest of the thing is no better.