--Thanks to Courtney at Artist Daily for spotlighting my post "Visually Similar" in your latest online forum--
In the summer of 1980, I knocked on the door of the Crescent Wrench Factory in Jamestown, New York to see if I could do a sketch of the machines inside.
The shop manager was reluctant to give permission at first, but eventually agreed as long I wore a hardhat, goggles, and earplugs— and stayed out of the way.
I set up near a machine where a huge mechanical hammer repeatedly crashed down on the forged pieces to trim off the excess margin. As the workpieces were trimmed, they fell down a chute to a bin in the lower right.
I met the operator during one of his breaks, and he explained how the cables of his wrist restrainers were timed to pull his hands out of the way of the hammers.
In 2011, production of Crescent wrenches moved to China.
Crescent company on Wikipedia
Video of how a combination wrench is made
The sketch is drawn with gray markers, charcoal, and pen.
At right is a levels histogram to address the comment by Katherine.