Components › Case

THE CROWN

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1. General description

With the winding stem, the crown creates the link between the outside of the case and the movement, inside the case.

By applying a rotational movement between the fingers, the watch user can wind it, set the time, or correct the date, to name only the main functions that can be assigned to it.

The various functions generally associated with the crown can be arranged in tiers, similar to a car gearbox.
By pulling out the crown, one moves from the winding position to correcting the date / Calendar.
By pulling the crown out again into a third position, one can then correct and adjust the displayed time.

Over nearly two centuries of existence, the crown has evolved and undergone various types of construction. Nowadays, most crowns are water-resistant. They are directly screwed onto the end of the winding stem.

Figure 1

Press-fitting of a Crown tube into the Case middle

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Figure 2

Testing of the adjustment of a Crown on its tube

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When the Crown is pulled into its different positions (correction of the Date / Calendar, setting the time, etc.), the Crown slides on a tube directly pressed or screwed into the Case middle. The Crown tube limits its lateral Set in order to reduce the risk of Winding stem breakage, to offer greater comfort and to guarantee Water resistance between the Crown and the Case. For better Water resistance (particularly for diving watches), a Threading or a bayonet machined onto the tube allows the Crown to be locked onto its tube by compressing the the Gaskets / Seals that link them.

For ergonomic reasons, the Crown is generally placed at 3 o’clock, but no rule imposes this practice.

Through its role as a physical connection and its prominence on the periphery of the Case, the Crown is, in design terms, an excellent medium for identity and Decoration.

2. History

It was Adrien Philippe who invented the winding Crown (and, de facto, the Winding stem) in 1842. An invention that would lead to his meeting, two years later, with Norbert de Patek and the history we know that followed.

The crown then only serves to wind the watch’s spring and has no other function. In 1847, another illustrious watchmaking inventor, Antoine Le Coultre, filed the patent for the first lever winding mechanism. From then on, the crown allowed the displayed time to be corrected in addition to winding the mainspring.

In the 1920s, Rolex filed a patent application for a water-resistant crown screwed onto its tube. It then compresses the gasket / seal and improves its water resistance. This system still predominates in the manufacture of sports watch crowns, and in particular, diving watch crowns.

3. Materials and Decoration

The technical part of a crown is often made of steel. Its aesthetic and visible part can, for its part, be made from almost any type of Materials (Metals, Sapphire, minerals, plastics, rubber, etc.) and is firmly attached to the technical part in the form of a cap.

The Crown can be engraved (Decoration or brand logo). A medallion (logo) or a stone (Cabochon) can be set into it.

4. Artisanal manufacturing of a Crown

The production of Crowns is generally handled by specialized subcontractors. The craftsman can, however, manufacture relatively simple Crowns using a lathe, or even a milling machine or an automatic lathe. For more technical Crowns or for better control of production costs, the craftsman can also acquire standard or customized technical bases from specialized subcontractors and only produce the aesthetic cap.

5. Industrial production of a crown

Most crowns are produced on an industrial scale.

With this method, profile turning is the preferred technique. The crown and its various components fit perfectly within the dimensions and operations suited to automatic lathes. For the cap or the medallion of a logo to be set, techniques such as electrical discharge machining (EDM) or stamping may be used. Once machined, the crown will be decorated (diamond polishing, satin finish, shot blasting (micro bead blasting), setting (stone/jewel setting), etc.) and then assembled.

6. High-tech production of a crown

Here, new technologies concern exclusively the aesthetic part of the Crown (its cap).

New materials (plastics, composites, ceramics) or vulcanized rubber overmoldings make use of the most recent technologies in terms of injection, machining and assembly.