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 bearings actually squeeze the rod a little bit, making a temporary indentation in the surface that works just like a screw thread would. As the bearings roll on, the rod bounces back to its ...

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 ...