I picked up some handscrews at a yard sale last week. Three of them were classic wood-screw handscrews, which I've seen but never owned, but one was an oddity, designed like the traditional wood screw tool, but with metal screws operating in T-nut-like inserts in the jaws. In the picture, the handscrews are, left to right, a wood-screw model, the metal-screw model oddity, and a modern Jorgsensen-type handscrew with left and right hand threads.
The screws on the metal-screw oddity are buttressed toward the handle, which seems overkill, but the company (all I can read of the maker's label is "---o Vise Company," with, perhaps, a California location) was obviously determined to put a good product out there.
When we first moved back to California in 1973, the local library had quite a few old beginner's woodworking texts. I recall one warning against getting the jaws on a wood-screw handscrew out of parallel, with a frightening picture of the screws splitting from being strained off-axis. Sure enough, the middle screw on the metal-screw oddity is bent.
