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caliber 324 sc
Unlike most Patek Philippe movements, the caliber 324 is one of the few with a balance wheel that beats at 28,800 vibrations per hour. The high frequency contributes to accuracy, but it requires extra power. This need challenged Patek Philippe’s designers, who work under strict guidelines (internally known as Formula A) that limit the thickness of the movements and therefore the power the mainsprings can generate. Musy and his team altered the profile of the caliber 324’s gear teeth with a configuration that reduces friction.
The new design also enhanced the consistency with which Patek produces the movement. “There is always a slight variation in tolerances from one piece to the next, which can change the way the pinions and wheels line up,” says Musy. “The new teeth compensate for this difference, which is slight because we stamp our parts. At companies that rely completely on CNC [computer numerical control] machinery to mill them instead, the problem can be worse because that method is less precise.”
These varying production methods distinguish the larger, established movement makers, which tend to use the expensive and precise stamping process, from the newly sprung boutique manufactures that have capitalized on the more accessible automated CNC milling method. Producing large quantities of accurate movements on the scale of Rolex or ETA requires a huge investment in stamping machinery and machine tool expertise—something that many horological connoisseurs fail to appreciate.
Precision Guidance Systems
James D. Malcolmson
11/01/2006