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: Drawing 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 to which it clips onto to be closed, thus preserving 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

As it is a simple disc of brass or german silver, the Barrel cover / lid can be entirely manufactured using a Lathe (type 70). Like the barrel drum, a Drop occupies the center of the cover. It defines the height Shake (play) of the Barrel drum relative to its arbor and limits the 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, 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. Industrial production method

As with the Barrel drum, profile turning is the best production method in terms of quality and cost, especially since it has no teeth. Its manufacturing is fast and involves no notable difficulty.

The decoration (Circling, etc.) can be performed using dedicated machines. Once the cover is decorated, it can receive its surface treatment (galvanic or PVD), and its manufacturing is then complete.