The precision of a Swiss calibre speaks to centuries of expertise and meticulous care. Few mechanisms rival the ETA design for its blend of robustness and elegance. Explore how each component works in harmony to mark every second with a steady pulse.
Anatomy of a movement
A mechanical calibre relies on a chain of parts that convert stored power into regulated motion. Balance wheel controls oscillation. Pallet fork passes impulses to the escape wheel. The escape wheel distributes torque through the train of wheels. The gear train transfers power from the spring barrel to the hands. The main spring barrel stores and releases energy in precise steps. Each piece must align with micron-level tolerance for flawless function.
Manufacturing journey
Every ETA calibre begins as raw brass and steel plates. Machinists first cut base plates on CNC machines programmed with dimensions down to one hundredth of a millimetre. Quality control ensures no plate deviates beyond a tight limit. Next, wheel spokes undergo forming and polishing. Jewel holes receive rubies to lower friction. Skilled assemblers then mount each gear by hand under magnification.
After preliminary assembly, technicians install hairsprings and balance wheel assemblies. These fragile coils require exact curvature to yield a consistent oscillation rate. Once the complete movement forms, it passes through multiple checks. Tiny screws receive final polish. Bridges align exactly with pillars. The result stands ready for timing tests.
Jura’s role in testing
At the Jura facility, each calibre moves to a timing station. Multiple positions mimic wrist movement. A precision timing machine records rate deviation over 24 hours. If a movement runs too fast or too slow, a watchmaker adjusts the regulator by shifting weights on the balance rim. Once within the prescribed tolerance, the piece receives a final inspection.
Next, a humidity and pressure trial simulates real-world wear. Technicians place the calibre in a chamber where temperature cycles stress metals. After this treatment, the timing test is repeated to confirm stable performance. Each approved movement leaves Jura with a certificate that details its average daily rate, amplitude, and beat error. These figures guarantee reliability from the moment the calibre enters its new case.
When to service a movement
A well-cared for mechanical calibre lasts for generations but requires service at regular intervals. Most experts suggest a full overhaul every four to six years. During a service, watchmakers disassemble the movement, clean all parts in ultrasonic baths, and replace worn jewels or barrels if needed. New lubricants are applied to reduce friction and preserve metal surfaces.
Delaying maintenance can allow oil to thicken and spread unevenly. This extra drag accelerates component wear and risks larger problems down the line.
Explore the ambition and attention that drive Swiss manufacture. Discover more and choose your next calibre at the Jura Watches website.
