Part of that is probably because we’ve gotten so good at making them that they’re seen as cheap commodities, but the physics and engineering behind the screw thread is interesting stuff.

The guys from the YouTube channel How To Make Everything have been looking at one such sketch, a screw thread-cutting machine. At first glance, it seems a little flawed. Threads are hard to make ...

When you put it to use, the extractor penetrates a hole punched or drilled in the top of the screw and its reversed threads grab hold so that the screw can be twisted out. A selection of screw ...