WINDING STEM

The winding stem appears with Jean Adrien Philippe’s invention of the winding mechanism in 1842. At this point in history, Antoine Le Coultre had not yet invented the time-setting mechanism, and the stem exclusively operated the winding mechanism, from which the name “winding stem” came in this short period of time. It was only in 1847, five years after Adrien Philippe’s discovery when Antoine Le Coultre invented the setting lever mechanism, which provides the dual winding-time setting function without requiring the use of a key. Since the end of the 19th century, the mechanism has evolved, and depending on the requirements, it has become more complex (date adjustment, other functions). Materials and manufacturing methods have sometimes appeared since the late 20th century, although most constructions remain very traditional in the materials used as well as in the manufacturing methods.
The winding stem is a relatively easy component to manufacture, regardless of the method used. The artisan begins by performing all the turning operations that constitute the bulk of the work, ensuring the turnings’ concentricity given the winding stem’s delicate length-diameter ratio. The artisan can then thread the end of the winding stem on the same lathe. The next step takes place at the workbench, where the artisan files the four faces of the square on which the sliding pinion will slide. This operation requires a certain dexterity as the square is long and must be perfectly regular. The surfaces are then polished or smoothed according to their function, and the winding stem can undergo its heat treatments (quenching and tempering). The thermal treatments of the winding stem are relatively challenging to succeed due to its significant length and small diameter. Thus, the heat treatment may not be homogeneous, and stem deformations are unfortunately always possible during these steps. A brief step of polishing and smoothing will restore the winding stem’s colour, and it will be ready for assembly. Finally, the length adjustment of the stem will be done during the movement’s casing.
Automatic lathe is the most suitable machine for producing winding stems on the industrial level. All operations (turning, threading, and square milling) can be performed in a single cycle. Depending on the chosen steel alloy, the winding stem may not require additional heat treatments. Finally, and depending on the desired level of finishing, the end treatments, particularly polishing, can be done by hand or, on a large scale, in a polishing drum, for example.