Components › Movement

THE BARREL COVER / LID

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Figure 1: Exploded view of the Barrel (motor organ (power source))

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Figure 2: Diagram of a Barrel cover / lid

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1. General description

This is one of the four components of the Barrel, which is itself the Motor organ (power source) of a mechanical watch. As its name suggests, it allows the Barrel drum it clips onto to be closed, thus protecting the Mainspring from dust. The Barrel cover / lid is made from the same Material as the drum (in Brass or in German silver). In rare cases such as extra-thin and/or skeleton watches, the Barrel cover / lid can be openworked or simply absent.

2. Traditional manufacturing method

Being a simple disc of Brass or German silver, the Barrel cover / lid can be entirely made using a Lathe (type 70). Like the Barrel drum, a Drop occupies the center of the cover. It allows the height Shake (play) of the Barrel drum relative to its Arbor to be defined and limits friction points between these two components. The outer diameter is machined with an angle that allows the cover to clip into its housing in the drum itself, which is turned with the same angular value. Two notches are generally cut around the periphery of the cover. They can be milled or filed later. These notches allow a closed barrel to be opened. The Decoration (circling, etc.) can also be carried out using the lathe or on dedicated machines. Once the drum has been decorated, it can receive its surface treatment (galvanic or PVD). Its manufacturing is then complete.

3. Méthode de production industrielle

Comme pour le tambour de barillet, le décolletage en est le meilleur moyen de production en termes de qualité et de coût d’autant plus qu’il ne possède pas de denture. Sa fabrication est rapide et ne comporte pas de difficulté remarquable.

Les opérations de décoration (cerclage, etc.) peuvent être réalisées à l’aide de machines dédiées. Une fois le couvercle décoré, il peut recevoir son traitement de surface (galvanique ou PVD) et sa fabrication est alors terminée.