I came home today and wasn't quite satisfied. I never am with most jobs. I wasn't able to figure out how to get the handle that you see here (which is actually connected to the long threaded rod) out of this sliding jaw. I think about stuff like this all day long while I'm working. Removing it would allow me to clean it up a bit more and the threads really needed to be greased badly.
This is what it looks like inside. It's almost like a Castle Nut but 2 of the ears (at opposite sides) are punched down into what appear to be little recessed areas in the handle. I thought maybe this was a threaded nut and having the ears pressed down was a way to hold it in it's position.
I started in on it with a big hammer and a punch trying to unscrew it. I broke one ear off which was fine since I figured that the tolerances would probably allow me to use different ears after all these years. Then I broke the other ear off. Then it started spinning pretty freely but did not appear to be walking off at all. WTF? Maybe it's reverse threaded? Nope.
No threads at all. I finally got it out and the threads lubed. This is old world craftsmanship. It's so simple it's impressive. The clamping force is all done by the female threaded nut on the other arm. Without this "Castle Nut-like" fastener, the handle just unscrews. The fastener backs out (with the handle) and hits the inside of that moving jaw and then backs out the entire jaw. It doesn't even need to be all that secure. I suppose if push came to shove I could stick the tip from a MIG welder down in there and weld a big fat washer to the handle just before it touches the jaw and it would do the same thing. This thing is super cool. A friend thinks it will rust now that I've hit it with a wire wheel but I think it'll be fine. It's so dry up here. Besides the rat rod look is pretty sweet.