This Rolex 6084 with the Caliber 645 movement underwent a complete disassembly, cleaning, lubrication, and reassembly. During testing, a significant timing differential was observed between certain horizontal positions, indicating an imbalance in the balance wheel. To correct this, dynamic poising was performed—precisely removing microscopic amounts of material from the balance to achieve even amplitude and consistent rate performance across all positions. Running the watch on only a few winds and checking timing in 8 horizontal positions provide the locations on the balance to add or remove weight. Once adjusted and regulated, the Caliber 645 movement ran with good accuracy and amplitude.
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Rolex Bubble Back History
The Rolex Caliber 645 was part of the brand’s early generation of automatic “Perpetual” movements, produced during the late 1940s and 1950s. It featured Rolex’s “bubble back” rotor system, known for its reliability and smooth winding action. The Cal. 645 powered models such as the Rolex Oyster Perpetual reference 6084, bridging the gap between early self-winding mechanisms and the more refined movements that followed.