Hi folks,

Happy New Year!

I have a challenge for everyone. I've just bought an old monkey wrench.
I bought it because I couldn't figure out how it had been made, and I
wanted to know. It's marked "Trimo" and was made by the Trimont
Manufacturing Co. of Roxbury, Massachusetts. Someone here might have the
same wrench.

Anyway, the wrench has an approximately rectangular hollow channel in
which the movable jaw slides. The channel has closed sides, i.e., it
isn't a T-slot. The wrench appears to be forged. The movable jaw is
marked "Drop Forged", although the fixed jaw isn't.

There is a line around the whole of the wrench, which appears to have
been made at the junction between the forging dies. The line also goes
down the back wall of the hollow channel.

I'm puzzled because the channel has sharp corners. If the corners were
radiused, I could imagine that the body of the wrench was a solid
forging, which later had the channel cut using an end mill or small
grinding wheel. But the corners are sharp.

There are no visible machining or grinding marks inside the channel.

I can only think that perhaps:
(i) The channel was punched out in a secondary forging operation.
(ii) The channel was created in a complex forging (possibly forge
welding) operation designed to make hollow parts.
(iii) The body of the wrench is actually a sand casting.

I'm inclined to favour option (i). I'd be interested to hear what other
people think.

I even checked the patent listed on the wrench, but it says nothing
about how the body is made.

Here are some pictures:
http://www.mythic-beasts.com/~cdt22/trimo1.jpg
http://www.mythic-beasts.com/~cdt22/trimo2.jpg
http://www.mythic-beasts.com/~cdt22/trimo3.jpg

Best wishes,

Chris