Originally Posted by Foxbat
Thread-cutting machine tools - yes, later, and yes, the screw thread can be cut by hand, but the internal, female one requires a tap of some kind.
I presume these developments have been studied and documented, I would be curious to see them.
a tap is just a hardened screw with lengthwise channels cut in it for the shavings. as i mentioned, the male screws in wheel locks would have engaged matching tapped female ones. they would not have made individual screws with a file. they'd make a tap, then drill a hole, tap it and cut channels inside or drill holes partly overlapping the threaded hole to make a die. then harden it, and then make zillions of screws with the die, and tap zillions of holes with the tap, all closely matching & mating (till the taps & dies wore down, then they'd make new ones)
the spring bar latching one would be easier to make. they don't need to be particularly tight and immoveable to work as intended as long as they don't easily come off.
here's some we made earlier
(my uncle was a master tool and die maker)