Watchmaking: First Screw Made
Taking a 3mm O1 (cool hardening) steel rod and making a very tiny screw from it. Here is what will be the threaded portion still on the lathe next to the screw die plate I threaded it with.
The plate can thread screws down to 0.7mm up to 2.0mm.
The thin "string" is actually a jeweler's saw that I used to cut the slot on the screw's head for use with a flat bladed screwdriver.