What is Winding Stem?
The winding stem is the interface between the exterior and interior of a watch. Manipulation of the winding stem by turning, pulling, and pushing the crown winds and sets the mechanical movement. One end of the winding stem is threaded, where the crown is attached. The threaded side is cut to length depending on the size of the case. The other side of the winding stem has a square, which interfaces with the winding and setting mechanisms in the movement. The pivot on the end of the square steadies the winding stem as it turns.
Manufacturing of the winding stem by hand is often a micro-mechanics exercise that watchmaking students work on.