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Unbearable Thinness of Watchmaking Part 1

by Jonathan Ho on April 10, 2017

There was a time in watchmaking when gentlemanly proportions (think: focused on thinness and dressiness) went into retreat and brands started to pursue the aggressive, hyper-masculine and eventually steroidal sized 42 to 48mm geometrically-inspired wristwatches with overbearing bezels. They were of such popularity that during the crushing years of 2015 – 2016, the greatest purveyors of symbolic wrist-machismo: Hublot, Audemars Piguet and Richard Mille were reported by various Swiss economic agencies as being profit positive.

The headline of this essay “Unbearable Thinness of Watchmaking” alludes to Kundera’s own novel “Unbearable Lightness of Being” which itself alludes to Friedrich Nietzsche’s own doctrine of Eternal Return; a philosophy which dictates that all things occur over and recur repeatedly for all of eternity – that is to say – human history is preset and circular, all the same events will arise in perpetuity. Kundera however, posits that if eternal return were not true, decisions and thus consequences would have little meaning as the universe continues, indifferent to the phenomenon of choice – thus there is no “weight” and everything is “light” by extension everything is pointless. Given the revival of thinness in watchmaking, it would appear that Nietzsche’s theory that existence is an infinite cycle would appear to apply to the vagaries of watchmaking and by extension, watch collecting as well. I digress, so let’s get back to delving into why thinness is a sure sign of watchmaking prowess.

The classic Calatrava. Shown here is a vintage example- Reference 3590J.

Unbearable Thinness of Watchmaking Part 1

Ask any experienced watch collector for his list of “must have” complications and there’s a good chance that after listing a retinue of tourbillons, rattrapantes, minute repeaters and perpetual calendars, the majority would forget to pen down the humble and subtle ultra-thin category – A most unfortunate occurrence given the extraordinary savoir-faire and inventiveness required in the conceptualisation and execution of a truly magnificent ultra-thin movement.

Ultra-thin movements are a niche within a niche of complications, the appeal is so narrow (no pun intended) to the watch collecting gentry that many forget how the genre was initially a symbol of watchmaking prowess – the ability of a watchmaker to produce watches of superior thinness and simplicity was not only commercially successful but also aesthetically preferred – think the golden age of Longines, the evergreen appeal of Patek Philippe Calatrava and the Mad Men era thin dress watches – there’s a reason why every brand worth their salt can boast an attempt at ultra-thin watches at some point in their history, it’s because it is a sign that you knew how to make superior watches.

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Ultra-Thin, Ultra-Flat, Extra-Thin, Extra-Flat: A definition

While many of us (journalists included) tend to use the terms ultra-thin and extra-thin interchangeably, the truth is that these categories have distinct watchmaking definitions. Extra-thin watches generally describe thin watches whose movements are distinctly separate from the case of the watch itself whereas ultra-thin watches tend to describe watches where the calibre is itself integrated into the case or general architecture of the timepiece as in the example of the Piaget Altiplano 900P; the calibre 900P would not exactly run if removed from the watch itself. Allow us to elucidate:

Taking a total of 3 years of development, the 3.65mm thin Piaget Altiplano was once the world’s thinnest self-winding mechanical watch (a record which stood a year before being beaten by a sister brand). The achievement itself is possible because the calibre 900P is designed to use the 18-carat white-gold caseback as the mainplate of the movement. Strictly speaking, if one were to remove only the movement’s components leaving out the caseback, there would be nothing to hold the components in position. Furthermore, the gear train itself was designed to be set around the “dial” with hands below the plane of the bridges thus not only saving space but protecting the movement from grinding to a halt whenever the crystal was pressed hard enough (either by atmospheric pressure or physical pressing) to touch and in effect, stop the hands from turning causing the movement to “brake” and in extreme cases, break – it’s an issue unique to thin watches given the tighter tolerances in an ultra-thin watch. In fact, Piaget was a pioneer of watches so thin, the very act of prying open the caseback meant irreparably bending and damaging the very movement it sought to protect inside– the 2.08mm thick Lasalle caliber 2000 was so difficult to manufacture and service, it was eventually discontinued in 1979 and given the reliability challenges, watches of those nature are rarely attempted again.

Most people make the mistake of thinking design is what it looks like. That’s not what we think design is. It’s not just what it looks like and feels like. Design is how it works.” – Steve Jobs

Technical Challenges inherent in Thinness

Achieving maximum thinness in a movement is not just a mere matter of making existing components thinner, an ultra-thin movement requires that you consider a movement completely from the ground up in order to maximise economy of space. Thus, when Piaget created the calibre 900P with the approach of using the caseback as the baseplate or mainplate for the movement components, they were not only taking away one layer from movement architecture but also veritably taking a leaf out of Lepine’s book. Indeed, the revolution of thin movement architecture was heralded by Frenchman Jean-Antoine Lepine. Lepine ingeniously eschewed the sandwich style type of movement construction but doing away with the top plate of his 18th century movement and instead used a series of bridges and cocks to hold pivots of various train wheels and gear trains. He also experimented with various types of escapements which allowed for flatter construction and ultimately pushed the industry away from the thick fusée-and-chain type method of delivering constant torque and energy through the gear train to the balance wheel.

JLC Master Ultra Thin 1907

Thinness Challenge 1

That said, it’s one thing to go from fusée-and-chain thickness to standard mainspring barrel thinness and then to reduce that by an order of magnitude. The reason for this is that isochronism and precision requires adequate power to the balance wheel for it to maintain amplitude (that is the beats or swing) – too thin, and the mainspring cannot store adequate power, too thick and there isn’t enough clearance in a thin barrel, leading to power loss due to friction.

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Remember that as the frequency of the balance increases, which brings along with it greater timing precision (at higher frequencies the effects of disturbances like shocks dissipate more rapidly), it becomes more difficult to achieve a high power reserve as the mainspring barrel unwinds at a greater rate.

JLC Calibre 849 with hanging barrel style construction

Thinness Challenge 2

Much in the same way Lepine conceived of a movement from the ground up, watchmakers today have to decide what sacrifices and changes to make in movement architecture. Typically, a mainspring barrel is sandwiched between mainplate and bridge (but still rotatable to wind up the spring within) by an upper and lower pivot. When a watchmaker elects to remove the bridge and instead use only one pivot point (think: a spinning top spinning only on one point rather than secured between two points like a bicycle wheel) that sort of “hanging” construction is less stable and prone to minute wobbling which introduces friction and instability. Yet, with special design and care, it can be safe to do so while saving vital millimetres of thickness.

It’s easy to think of the winding barrel as a single component but it’s literally three parts – the barrel drum, home to the mainspring, the mainspring itself and the arbor where the mainspring is wound around. The arbor is itself attached to the ratchet or winding wheel – turned either manually via crown or through the automatic winding rotor. The exterior teeth of the drum then delivers stored potential energy into kinetic energy to the gear train as the teeth engage gear wheels.

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As mentioned previously, the sandwich type architecture of key barrel components of your regular mechanical movement can be relatively thick but eliminate the top bridge and barrel cover while inverting the order of components and you get to save over 20% of thickness – imagine that, improving thinness by 1/5 or 1/4 is no small feat. The “hanging drum” method of construction is particularly ingenious – by using ball bearing assemblies to secure the perimeter of the drum, the barrel is supported yet given leeway to turn without needing a top bridge to hold it in place. Additionally, thinness is not only improved but also endurance and resistance to shocks.

The micro-rotor in the Saxonia Annual Calendar is integrated into the “three-quarter plate”.

Thinness Challenge 3

Self-winding movements are traditionally thicker by virtue of their oscillating weights which are another separate layer of the movement, pivoting from the centre and winding the mainspring barrel. Some watchmakers get around this problem by moving the mass to the periphery of the movement but peripheral winding rotors are quite as effective as the central winding variety and then there’s the nagging issue of still being a layer (albeit a significantly thinner one). Then there’s also the option of a micro-rotor. Where the rotor is in the movement itself and part of its thickness rather than another layer on the base of the movement. Again, as with the peripheral rotor, performance is not optimal because it doesn’t have the laws of physics (read: leverage) on its side, thus designing, making and adjusting one to get good performance is another mine-field.

Stay Tuned for Part 2, where we explore how Bulgari, a relative newcomer to the serious watchmaking scene is making a splash with its new Octo Finissimo Ultra-Thin.

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