Boar sword cross bar

[Foxbat]

Originally Posted by kronckew

screws were known and laboriously hand filed, as were small intricate gears in pre-christian greece/rome. common metal screws were 16c and accurate screw cutting lathes were invented late 18c.

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.