The Eterna Calibre 1521 stands as a pinnacle of mid-20th-century Swiss horology, captivating vintage watch enthusiasts and hobbyist watchmakers with its innovative automatic winding system. Produced from the late 1940s through the 1960s, this calibre introduced Eterna’s groundbreaking five-ball-bearing rotor design, revolutionizing bi-directional winding efficiency and smoothness.
Historical Context
Debuted as part of the Eterna-matic lineup, evolving from earlier hammer-wound models like the Cal. 834.
Featured in dress watches and early tool watches, prized for reliability during an era of post-war innovation.
Exemplifies Eterna’s legacy in rotor technology, influencing modern automatics with low-friction engineering.
Technical Specifications
Type: Self-winding mechanical with central sweep seconds and date.
Dimensions: 11.75 lignes (26 mm diameter), approximately 5.2 mm thick.
Jewels: 25 (including shock-protected cap jewels).
Frequency: 18,000 vibrations per hour (2.5 Hz).
Rotor: Bi-directional, mounted on 5 micro ball bearings (0.65 mm diameter) for whisper-quiet operation.
Balance: Glucydur screwed balance with flat Nivarox hairspring; Eterna-U shock protection.
Mainspring: Eterniflex alloy for extended power reserve (around 40-45 hours).
Functions: Hours, minutes, central seconds, date (gradual change, no quickset).
Finishing: Perlage on plates, minimal markings for clean aesthetics.
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Watch Parts Enquiry
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Stem, Crown, Hands & Spares might be available for this movement.
Email us for rate and availability: [email protected]
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