Horology is an art form steeped in history and tradition. Although new and highly advanced materials are being introduced all the time, the underlying principles behind what makes a watch or clock actually keep time have not changed for hundreds of years.
With mechanical watches, there is an energy source (stored in the mainspring) and that energy is discharged in precisely measured increments. The mechanism that controls the release is made up of an escapement and oscillator, working together. The oscillator (the balance wheel and hairspring) is fed impulses by the escapement, and it is the oscillator which, in turn, governs the escapement’s rate. So each oscillation unlocks the gear train and forwards it a set amount.
It is a system invented by Dutch physicist, astronomer and mathematician Christiaan Huygens in 1675, and its fundamental workings have remained pretty much unchanged since then.
As successful as Huygens’ innovation has been though, it has natural limitations. His invention of the hairspring ensured that the balance swung backwards and forwards at an unvarying frequency—what is known as its isochronism. But that is in a perfect world. In reality, changes in the watch’s position, temperature variations, magnetic fields, even the types of lubricant used on specific points of the movement, can all have an effect on the regularity of the swing.
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The operation has been constantly augmented and optimized virtually since its inception, but has always stayed within sight of Huygens’ original creation.
However in 2017, legendary Swiss manufacture Zenith unveiled the biggest disruption to the antiquated arrangement since the 17th century.
The Zenith Defy Lab
With the release of their concept watch, the Defy Lab, Zenith offered a complete reinvention of Huygens’ foundation.
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Powered by their latest caliber, the ZO 342, it came with an all-new oscillator which supplanted the sprung balance design, incorporating more than 30 separate components into one single module measuring just 0.5mm thick.
All the work done by single constituents such as the balance wheel, hairspring, pallet lever, etc. in a traditional movement is now combined into one monolithic construction, which works on the principles of compliant mechanisms.
Compliant mechanisms, sometimes known as jointless structures, are those that transmit a force through flexible body distortion. In the case of the Defy Lab’s oscillator, it becomes a 30mm circular element, with a massively complex and erratically-shaped interior, all formed from monocrystalline silicon. The wafer-thin part is produced using Deep Reactive Ion Etching (DRIE) and the material renders it completely antimagnetic and impervious to temperature changes. In addition, because there are no mechanical joints, there is no friction and so no need for lubrication.
The oscillator has three main asymmetrical spokes branching out from its core which perform the duties of the hairspring in a conventional movement—as in, they provide a restoring force to the oscillator. These spokes, what Zenith call beams, also hold the pallets and the regulation assembly; the oscillator’s frequency can be fine-tuned by up to about 300 seconds a day by changing the position of a tiny fork on one of the arms, using variable inertia in the same way as adjusting the active length of the hairspring in a traditional caliber.
The outer rim of the component acts as the balance wheel itself and is spilt into three segments. Each segment has two oval apertures into which sits a tiny pin and makes up the anti-shock system by restricting lateral movement.
In addition, the work of the lever is taken on by two miniscule teeth set into one of the auxiliary arms that lock and unlock the escape wheel, which is one part not included in the circular mechanism.
In all, there are 20 different flexible elements in the ZO 342’s oscillator, all of differing widths, with the thinnest being a mere 20 microns.
The Defy Lab has a frequency of 15HZ, or 108,000vph, an incredible speed even by Zenith’s standards. The brand is no stranger to high beat mechanisms, having built the celebrated El Primero at the end of the 1960s.
But even that caliber and its 36,000vph pales in comparison.
The frenetic pace is helped by an amplitude (how far the balance wheel swings back and forth) of just +/-6°. As a comparison, a normal sprung balance oscillates around 270°+.
It results in not only a silky smooth motion to the seconds hand, but also an accuracy of around 0.5 seconds a day over 48-hours, an amazing precision when you think chronometer ratings from COSC require a variance of -4 to +6 seconds a day.
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The construction of the oscillator also ensures it stays accurate to the same degree for 95% of its 60-hour power reserve. With conventional calibers, the unwinding mainspring starts to cause noticeable discrepancies in timekeeping after 24-hours.
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Containing all this groundbreaking technology is a 44mm case forged from another material making its debut.
‘Aeronith’ is touted as the world’s lightest aluminum compound. Molten 6082 aluminum is poured into a mold where it is transformed into a metal foam using a proprietary process first developed by Hublot. The spaces in the foam are then filled in with a hypoallergenic, extremely lightweight polymer, resulting in a composite 2.7 times lighter than titanium and 10% lighter than even carbon fiber.
The Zenith Defy Lab Inventor
The original Defy Lab consisted of just 10 models, each presold to collectors and never made available to the general public.
With the success of their invention (the oscillator actually took the Innovation prize at the 2017 Grand Prix d’Horologerie de Genève) Zenith were able to commercialize their brainchild this year with the release of the production model, the Defy Lab Inventor.
As well as a better chance of actually being able to buy one, the Inventor also included a couple of other updates.
Firstly, the balance frequency has been upped still further. The ultra high speed 15Hz is now a positively manic 18Hz, or 129,600vph! In addition, the escape wheel on the Inventor is fitted with flexible silicon blades rather than the rigid teeth of the original, allowing for more consistent regulation.
Zenith’s creation is triple certified; it holds ISO 764 for magnetic resistance (exposure to 4,800 A/m), ISO 3159 for thermal insensitivity and the Chronometric+ Observatory certificate from TIMELAB.
The Zenith Defy Lab and Defy Lab Inventor represent something truly exceptional. The biggest breakthrough in mechanical watchmaking in more than 300 years, it is a mesmerizing blend of the very old and the absolute cutting-edge.
While the basic laws of timekeeping have stayed true to Huygens’ original vision, the way Zenith have gone about it has never been seen before.
With the first production model only just rolling off the line, it could well be the start of something very special in the fascinating world of horology.
Featured photo credit: @100percentpassion