This stage encompasses all the operations involved in adjusting the escapement. Proper escapement adjusting is essential for the accurate functioning of a watch and its chronometry. The interactions between the various components of a Swiss lever escapement must be meticulously adjusted in a very precise order.
In watches with a Swiss lever escapement, this mechanism comprises the escape wheel, the lever, and the double roller, even though the latter is integral to the balance staff and thus part of the regulating organ.
The spacing between each component, as well as the functional and vertical clearances, must be carefully fine-tuned by correcting numerous parameters (vertical positioning of components, placement of the pallets in the fork, position of the guard pin, length of the dart, etc.).
Historically, during the era of the assembly workshops (up until the late 19th century) and sporadically until the quartz crisis, the work was segmented and distributed among specialised workers operating from home. Specialists in escapement adjusting were referred to as “setters”.