Technical Archives - Revolution Watch

Technical Insights: Czapek Place Vendôme Complicité

Cheryl Chia — Mon, 16 Oct 2023 08:00:24 +0000

Technical Insights: Czapek Place Vendôme Complicité

A double balance and differential watch with a highly inventive construction.

Technical

Oct 16, 2023

The watch most renowned for its use of double balances and a differential is none other than the Philippe Dufour Duality. The Duality was launched in 1996 and it was the first wristwatch to incorporate double balances of any setup known today. In contrast to a resonance watch, which incorporates two separate gear trains and balances to improve rate stability through an exchange of energy, the principle behind a differential setup is to attain an averaged and therefore improved rate. When two balance wheels oscillate at slightly different rates, the differential balances out their rate difference.

The Duality has a beautifully simple architecture, where the wheel train is arranged diagonally across the base plate, with the small seconds display directly powered by the differential on the fourth wheel. As such, this configuration leads to the asymmetrical placement of the small seconds subdial at seven o’clock on the dial. However, what if the brief changes a little and it becomes necessary to preserve a symmetrical layout of the balances while also incorporating a seconds indicator?

This task is a lot less straightforward than one might initially grasp, as each objective imposes limitations on the other and on all other aspects of the movement. Hence, most watches of this nature are designed one without the other. While maintaining the crown at the conventional three o’clock position, placing the differential on the fourth wheel leads to an asymmetrical outcome. However, if the differential is positioned on the second or third wheel, it requires an indirect drive seconds indicator as the fourth wheel(s) will not yield an averaged output.

The Czapek Place Vendôme Complicité accomplished both aspects in the most unusual and intriguing way. Recently introduced, the watch was a result of a collaboration between Czapek and Bernhard Lederer. The fact that it took no less than Bernhard Lederer says enough of its complexity. In fact, Xavier de Roquemaural, the CEO of Czapek had a more complex set of directives, envisioning that the balance wheels be placed at 4.30 and 7.30 on the watch face and the differential at 12 o’clock to mirror the design of the brand’s foundational Place Vendôme model, which featured sub-dials in those exact locations.

Ingenious Layout

To achieve this, the movement features a convoluted but simply ingenious layout for the going train. Visible on the back of the watch are a pair of serially coupled barrels at the bottom that are wound via a crown wheel with integrated winding clicks. The mainspring barrel drives the pinion of the centre wheel, which is hidden beneath the dial. The centre wheel turns once per hour, driving the minute wheel that carries the minute pinion, which in turn drives the hour wheel, giving us the hour and minutes. Simultaneously, the centre wheel drives the pinion of the third wheel while the third wheel is positioned above the dial.

A closer look at the wheel train layout from the mainspring barrel to the differential. Central seconds is achieved with a LIGA auxiliary wheel

Impressively, the differential in the Place Vendôme Complicité uses planetary gears that have straight bevel teeth. Bevel gears are generally more complex to manufacture due to their intricate design requirements. It involves precise machining processes, such as cutting and shaping the teeth with high accuracy to ensure smooth engagement and minimize noise during operation.

The planetary differential comprises a sun gear (first third wheel), a ring gear (second third wheel), and three planet gears, all featuring bevel teeth. The three planet gears are held by a carrier – a chassis – made of black rhodium plated brass. The carrier is securely fastened to its shaft by a horizontal screw while the sun and ring gear are rotatably mounted with jewels installed directly in their hubs. The sun and ring gear have dual tooth profiles – flat teeth for traditional gear engagement and bevel teeth on their undersides to drive the planet gears.

The highly elaborate differential with bevel teeth. The planet gears are housed in a chassis that is fastened to the input shaft. As the sun and ring gears are identical in size and shape, power is always divided equally to both wheels

While the differential takes effect almost as soon as the watch is wound, it is still worth understanding how it does what it does in slow motion. As the mainspring unwinds, the carrier turns and the planet gears rotate on their own axis within this carrier. They will attempt to drive the sun and ring gears, which will turn slowly before picking up pace. Given that the sun and ring gears are identical in shape and size, the planet gears will distribute power equally between them.

The differential at 12 o'clock splits power to the fourth wheels, escape and balance wheels while averaging their errors in rate

Both wheels will then transmit power down their respective lines and to the balance wheels. As the balance wheel oscillates, it exerts a back-and-forth force on the escapement. The escapement, in turn, regulates the release of energy from the gear train. This interaction creates a feedback mechanism. As such, when both balances are oscillating at different rates and both third wheels are rotating at different speeds, the net effect is that the planet gears will minimize their speed difference and rotate at a speed that is a compromise between the two while maintaining a balanced power distribution.

It is worth noting that because this differential effect takes place on the third wheel, neither of the fourth wheels can directly power a small seconds function. It wouldn’t yield an intermediate or balanced output, at least from a theoretical perspective. In addition, both balance wheels in such a watch are typically adjusted to run at different rates, with the intention of achieving a balance. The goal is to find an intermediate rate that lies between the rates of each balance wheel individually, resulting in a more precise overall rate. One solution to achieve a small seconds would be to install an auxiliary train from the third wheel, but this would introduce additional inertia and play.

In the Place Vendôme Complicité, the differential is connected to a large auxiliary wheel on the same shaft. It is visible on the rear of the watch and it’s this wheel that drives the pinion for the central seconds. But look closer and you’ll notice that the individual teeth consist of cantilevered springs. This forms a reactive tooth profile that enables fuller penetration as it meshes with the central seconds pinion, eliminating backlash or play. It is produced using the LIGA (Lithographie, Galvanoformung, Abformung) process, an additive micro-electro-mechanical technique known for its exceptional precision.

A closer look at the auxiliary wheel that drives the central seconds pinion. It features a reactive tooth profile to reduce play during meshing

The Rest of the Watch

Offered in white gold with a grey dial or rose gold with a blue dial, the case has a diameter of 41.8mm and an overall height of 13.3mm due to its intricate gear train configuration and elaborate bevel gear differential. However, as most of the gear train is positioned on the dial, its height is merely 8.8mm, excluding the crystal. The level of finish seems to be very high, matching the ambitions of the watch. It features a full bridge that is openworked to showcase numerous sharp internal angles while the slim portion of the bridge that supports central seconds pinion is fortified by a black polished steel cap. The crown wheel with integrated clicks and click springs, a design also present in Bernhard Lederer’s Central Impulse Chronometer, subtly acknowledges the watchmaker for his contribution.

The full bridge has been openworked to showcase an abundance of internal angles

To provide a full view of its highly elaborate construction, the differential is supported by a sapphire bridge that is superimposed on another sapphire bridge that holds the fourth and escape wheels

The watch’s twin barrels provide a 72-hour power reserve which is indicated on the dial at six o’clock between the balance wheels. The balance wheels are free-sprung and operate at 3Hz. They are suspended by triangular bridges while the differential and the rest of the exposed wheels are supported by two sapphire bridges, one on top of the other, and the entire dial is protected by a box sapphire crystal. In the end, this is a watch that is as visually engaging as it intellectually exciting, a seamless blend of mechanics and aesthetics that belies an ingenuity born from narrowing the goal posts in the already exotic field of double balance and differential watches.

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FROM THE SHOP

Bell & Ross

Bell & Ross x Alessandro Palazzi x Revolution & The Rake Bellytanker Chronograph "Vesper"

$5,250.00

TECH SPECS

Movement	Self-winding caliber BR.CAL-301; 42-hour power reserve
Functions	Hours, minutes, small seconds, chronograph and date
Case	41mm; CuAI7Si2 bronze; water resistant to 100m
Dial	Sunray brushed with applied, gold-plated indices
Strap	Black calfskin; satin polished bronze folding clasp
Limited Edition	Limited edition of 50 pieces

The post Technical Insights: Czapek Place Vendôme Complicité appeared first on Revolution Watch.

What goes on inside the new Tudor manufacture in Le Locle

Jeremiah Chan — Thu, 27 Jul 2023 07:00:01 +0000

What goes on inside the new Tudor manufacture in Le Locle

Tudor steps out on its own with a new manufacture

News

By Jeremiah Chan

Jul 27, 2023

Ever since Rolex founder Hans Wilsdorf created “Montres Tudor S.A.” in 1946, the expressed mission of the brand was to produce watches that would, in Wilsdorf’s own words, “sell at a more modest price than Rolex watches, and yet one that would attain the standard of dependability for which Rolex is famous.” To that end, Tudor has always sat in the colossal shadow of big brother Rolex. Vintage Tudors would bear the mark “Original Oyster Case by Rolex Geneva” as proof that Rolex had certified their quality and reliability. Even after Tudor started producing its own in-house movements in 2015 through movement manufacturer Kenissi, a majority of the operational processes including assembly, quality control and R&D were conducted at Rolex and Tudor’s joint headquarters in Geneva. That is no longer the case with the completion of Tudor’s brand new manufacture in Le Locle.

Kenissi Manufacture assembly

The bucolic city of Le Locle (third smallest in Switzerland) is a wholly suitable location to house a manufacture, not least because of its historic significance as the birthplace of the watchmaking industry (along with neighboring La-Chaux-de-Fonds), but many of the industry’s component suppliers continue to operate there. This close proximity to its suppliers as well as integrating Kenissi into the manufacture’s neighboring wing ensures Tudor can continue to offer hard-to-beat value proposition watches at extremely competitive price points. A week before the madness of Watches and Wonders would descend on Geneva, Tudor opened the doors to its new manufacture, welcoming a select group of visitors for the very first time. We were fortunate enough to be given an opportunity to peer behind the curtain of watch manufacturing at an industrial-scale, but fine-tuned to extract every ounce of efficiency imaginable.

TUDOR Manufacture Building

Located on Rue de France 63, the manufacture cuts an imposing figure on the side of a single carriageway, belying its relatively compact profile of 150 meters in width and rising 30 meters above the ground. Alternating bands of corrugated metal paneling painted in Tudor’s unmistakable red distinguish one half of the structure to the other, a more muted, steely grey exterior that houses the movement assembly operations of Kenissi. Three years in the making, the manufacture became operational in 2021 but Tudor estimates that it will take a further two years to relocate all staff, machinery and equipment from its previous premises in Geneva.

I was told that at the very least, the new references from this year’s Watches and Wonders fair will be manufactured in this new building. Well let’s put some figures into perspective: Tudor currently produces 700 different watch references which are sold in 80 countries. Completely centralizing production to meet the demand from 1,700 points-of-sale is no mean feat and would most definitely require meticulous planning and a fair bit of time.

Kenissi Manufacture Building

The Foundations

From the get-go, Tudor’s ultimate goal for its new manufacture was maximum optimization and efficiency in order to maintain an affordable product price point for the average watch consumer. Ironically, they didn’t make it easy for themselves by picking a site with significant amounts of groundwater. That meant extensive construction work would be necessary to ensure the foundations were sufficiently solid to bear the weight of the above-ground structure.

Firstly, 330 concrete pillars each measuring a whopping 30 meters long, were drilled into the lower-level bedrock to create a firm foundation. Secondly, the underground structure containing the infrastructure vital to the building’s functioning had to be shielded from the surrounding moisture. A waterproof membrane consisting of tiny yellow vessels envelops the concrete walls of the underground structure, creating an impenetrable barrier. Despite the environmental challenges of building on such an area, the choice of location might make more sense if you knew that the land the manufacture sits on is owned by none other than Rolex. Yes that’s right, Rolex doesn’t only make watches, it is a landowner as well.

TUDOR Manufacture assembly

But back to the building’s design. What are some of the vital infrastructure that can be found under the ground? There is a heating, ventilation and air-conditioning (HVAC) system that regulates the building’s temperature and humidity levels, guaranteeing a consistent environment that is crucial for the assembly of movements and entire timepieces. Standard fire safety regulations require a regular water sprinkler system to put out internal fires but a liquid-based system is not suitable for production areas. Due to the delicate nature of the equipment and manufacturing components found in those areas, a “dry” fire suppression system using nitrogen had to be installed instead.

The entire building’s insulation consists of wood taken from the surrounding forests which are first broken down into flakes and then compressed into cylinders by a specialized machine. These cylinders limit the need for active heating during the winter months, thereby reducing the building’s overall energy consumption. Another nod to Tudor’s sustainability efforts can be found on the roof where 442 solar panels generate enough electricity to meet most of the building’s energy needs.

TUDOR Manufacture testing

The Automated Stock System

Now that we know what keeps this new manufacture humming along, let’s get to the heart of the matter: how wristwatches are made here. We start with the heart of the manufacture which is literally at the center of the building, the black portion in the middle that separates movement assembly from final assembly. This section contains the automated stock system, a completely autonomous, cutting edge solution for the efficient management of mass production operations. Tudor requested that this system remain a secret as it had been customized to meet their specific needs and so photography was prohibited in this area, which is usually closed off to visitors anyway.

It starts with a cavernous vault located behind reinforced walls, secured by a sizable round-shaped door similar to the type found in walk-in bank vaults. We weren’t allowed entry into the vault either unfortunately, but we were told that this storage area is so vast that it is able to house every single component necessary to assemble the 700 different watch references in current production. The components themselves are stored in standardized trays with multiple compartments. The main benefit of using standardized trays is the efficient use of the storage area available as the racks that store the trays can be constructed with uniform dimensions. As with the production assembly areas, a waterless fire protection system has been employed here as well.

TUDOR Manufacture Testing

When a watchmaker requires a particular set of components, they may request for it and the system automatically retrieves the requisite tray from the vault and places it on a fully automated tray delivery system that connects the whole building. Dials, movement parts, cases and even fully assembled watches can be delivered to any workshop within 10 minutes, whether from the central vault or between production areas. Each workshop has its own delivery station serviced by two main lifts to send and receive the component trays.

TUDOR Manufacture Testing

The assembly and fine-tuning of such a unique just-in-time delivery system was probably one of the most complex and time-consuming operations during the building’s construction. However, with such an advanced system, Tudor have significantly reduced the need for watchmakers to leave their benches to collect parts and they can have uninterrupted focus on their individual tasks.

TUDOR Manufacture assembly

The Movement Manufacture – Kenissi

The next step of the production journey takes us to Kenissi, Tudor’s in-house movement manufacturer. If you don’t already know the story behind Kenissi (translated from the Greek word ‘Kinesis’ meaning ‘in movement’), here’s a quick rundown. Back in 2010, Tudor founded a project with the aim of developing the capability to produce internally robust, high precision, high power reserve movements with the capacity of being customized with additional complications. It took five years of R&D but eventually the first Tudor manufacture caliber, MT5621 made its debut at Baselworld 2015 in the now discontinued North Flag. It was COSC-certified and came equipped with a variable inertia balance with micro-adjustment screws, an amagnetic silicon hairspring and a healthy 70 hours of power reserve.

Kenissi Manufacture assembly

Relying on the manual dexterity of highly-trained watchmakers, assembly is done exclusively by hand. Once a particular process is completed, the partially assembled movement and its holder is placed on a white tray that travels on a conveyor to the next stage of the assembly, at the right time and in the correct orientation. However, certain repetitive processes such as lubrication and clearance measurement of the wheel train have been further automated in order to save even more time.

Kenissi Manufacture assembly

The integration between man and machine is on full display here. The automatic stock delivery system transports the right components from the vault to the appropriate work stations at the start of the two assembly lines. A movement starts out as a bare base plate, mounted on a plastic holder which has a RFID tag underneath. RFID tagging enables data collection and full traceability of all movements during the assembly process, and the data used to constantly improve product quality and overall performance of the assembly lines. The holders themselves come in three sizes to fit all the base calibers used in Tudor watches: small (T20 & MT52 series), medium (T601 & MT54 series) and large (T603 and MT56 series).

TUDOR Manufacture assembly

The movement assembly floor is located at ground level so watchmakers do not have to waste precious time traversing different levels daily to get to work. The environment in this area is highly controlled with large triple-glazed windows that can adjust in real-time their opacity using electrochromic technology, allowing just the right amount of heat and light to filter into the room. Access is granted through an air-lock system that removes dust and other contaminants from clothing. Staff then don anti-static coats over their clothing that further prevent dust particles from attaching themselves to the fabric. The HVAC system found in the basement generates a continuous flow of air from ceiling to floor, refreshing the air supply 3.5 times an hour and prevents dust from falling onto work surfaces.

Kenissi as an entity would be formally introduced in 2016 and in one short year, it would offer its movement development expertise to third parties starting with Breitling. Today, the brands that utilize Kenissi movements in their watches include Fortis, Norqain, TAG Heuer, Bell & Ross, Ultramarine and Chanel, with the French luxury house taking a 20% stake in the manufacturer in 2018. Today, Kenissi is fully integrated with movements produced entirely in Switzerland with some components supplied by strategic partners that are owned by Tudor. A notable exception is the silicon hairspring which is still supplied by an independent third party but the hairspring’s design and composition remains solely Tudor’s.

The Final Assembly

The final assembly area is similarly on the ground floor with the same infrastructure as the movement assembly department. The watchmakers here are trained to assemble at any particular stage, every single reference from the entire product catalogue. They do not work in isolation but in groups of four called a cell. Each watchmaker’s bench is laid out with the exact same tools and equipment so any stage of final assembly can be undertaken at any workstation. The four processes that occur in a cell are dial fitting, hands fitting and two watchmakers dedicated to encasing as it is a comparatively more time-consuming task and more manpower is needed to keep up with production demand.

To build camaraderie within a team, watchmakers generally do not switch over to other cells. Checks are conducted at each stage to ensure a consistency in quality and a final round of quality control completed by an independent, standalone cell. Any issues found will be immediately rectified by the watchmaker that last worked on the watch from the previous stage. While the vault may have room to store every necessary component, fully assembled watches are not stored on site and have already been allocated to points of sale worldwide. Such logistical planning to achieve just-in-time manufacturing and distribution is extremely impressive.

Performance Control

We go up a floor to the performance control department where assembled watches are put through a battery of tests to measure their accuracy, power reserve, water and magnetic resistance. Even here, Tudor have designed the testing processes to be fully automated. Robots following pre-defined pathways on the floor carry trays of watch heads to the various testing stations completely unaided. The testing machines are massive pieces of equipment with a combined weight of 46 metric tons, and all proprietary to Tudor. They are all connected to a GPS signal that ensures all measurements are absolutely precise. Such specialized equipment are crucial as the brand has grand plans to expand METAS certification moving forward.

There is even a small METAS office at the far end of this floor staffed by employees directly from the testing organization to maintain independence of testing. You may recall the first METAS-certified Master Chronometer from Tudor was the Black Bay Ceramic back in 2021 and a second piece from this year’s Watches and Wonders has also been certified, the 41mm Black Bay with a red bezel. There are eight tests in total to complete METAS-certification and four of them are related to magnetic field exposure. It’s no wonder that one of the most prominent pieces of equipment is the permanent magnet that is capable of exposing watches to a magnetic field strength of 15,000 gauss, the METAS standard of magnetic resistance.

TUDOR Manufacture testing

It’s pretty cool to see trays of watches being conveyor-ed into this giant magnet and put through their paces. Another nifty machine is a stocker that is able to store watches in different positions and at different temperatures during the various stages of testing. This stocker is fed by multiple conveyor belts that transport the watch trays dropped off by the robots continuously. This is a section of the manufacture that never sleeps and since January this year, tests have been running 24/7.

Final Quality Control

Arriving at the top floor of the manufacture, we find the department that conducts the final quality control checks and marries watch heads to bracelets before they are shipped to boutiques worldwide. The technicians here, like their colleagues in the final assembly department, are trained to fit any bracelet or strap of any material for all watch references. You may think attaching a strap is a cinch and takes no time at all but to do so repetitively and perfectly every single day, when the tolerances between metal bracelets and cases are extremely fine, is a monumental undertaking. Any slip of a spring bar or a tool will mar a perfectly finished case and it will have to go back to be refinished, affecting production lead times. The training that technicians undergo is to repeat the task with no time pressure whatsoever until they are fully confident of executing perfection. Only then will they be allowed to work on commercial pieces.

TUDOR Manufacture bracelet fitting

Another incredibly important function that is performed here is quality control of watch components when they are first delivered to the manufacture. Dials, bracelets, cases all have to be checked individually to ensure they are within tolerances before they can be stored in the vault, waiting to be called up by watchmakers during assembly.

TUDOR Manufacture Testing

TUDOR Manufacture assembly

TUDOR Manufacture Final Assembly

I have to say it was an absolute treat to have been given an all-access tour (save for the vault!) into Tudor’s new manufacture and having visited the factories of other brands, this has probably been one of the most comprehensive and insightful displays of industrial-scale watchmaking at its finest. The entire operation has been thoughtfully designed to manufacture a product of exceptional quality at a price point that is incredibly hard to match. As Rolex continues to move upmarket, Tudor has remained true to the mission set out by its founder and at the same time continually improves their offering by incorporating quality standards such as METAS. Such a value proposition is one that I can totally get behind and undeniable proof that Tudor has come of age and deserves to stand on its own.

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FEATURED FROM THE SHOP

Bell & Ross

Bell & Ross x Alessandro Palazzi x Revolution & The Rake Bellytanker Chronograph "Vesper"

$5,250.00

TECH SPECS

Movement	Self-winding caliber BR.CAL-301; 42-hour power reserve
Functions	Hours, minutes, small seconds, chronograph and date
Case	41mm; CuAI7Si2 bronze; water resistant to 100m
Dial	Sunray brushed with applied, gold-plated indices
Strap	Black calfskin; satin polished bronze folding clasp
Limited Edition	Limited edition of 50 pieces

The post What goes on inside the new Tudor manufacture in Le Locle appeared first on Revolution Watch.

In-Depth: The Secular Perpetual Calendar by Furlan Marri x Dominique Renaud x Julien Tixier for Only Watch 2023

Cheryl Chia — Wed, 19 Jul 2023 07:00:53 +0000

In-Depth: The Secular Perpetual Calendar by Furlan Marri x Dominique Renaud x Julien Tixier for Only Watch 2023

Astonishing solutions to perpetual timekeeping at an astonishing price.

Furlan Marri

By Cheryl Chia

Jul 19, 2023

One of the biggest highlights for Only Watch 2023 is an unassuming watch that bears the name Furlan Marri, a brand best known for creating refined but accessibly priced, vintage-inspired watches. At a cursory glance, there is virtually nothing that suggests it is anything more than a calendar watch that displays the day and date on two subdials with the month indicated on the periphery by a central hand. It is only upon a closer inspection that you see a tiny Maltese cross pivotably affixed to a smaller central hand, which indicates that it serves as a leap-year indicator, making the watch a perpetual calendar.

Pièce Unique Secular Perpetual Calendar by Furlan Marri x Dominique Renaud x Julien Tixier for Only Watch 2023

However, it will require more than an average human lifetime to observe that this Maltese cross will accurately mark 2100 as a common year, not a leap year. This is because it is not just a perpetual calendar, but a secular perpetual calendar. In other words, it belies a masterpiece of a movement.

As a recap, the Gregorian calendar dictates that a year has an extra day at the end of February if it is divisible by four. However, if the year is also divisible by 100, it becomes a common year with only 365 days. But if the year is also divisible by 400, then it becomes a leap year again. By design, a regular perpetual calendar, which only encodes a four-year cycle, will interpret the years 2100, 2200 and 2300 as leap years when in fact they are common years. As such, a manual adjustment by one day is required on March 1 of these years.

A secular calendar, on the other hand, will account for all the anomalies of the Gregorian calendar, encoding a 400-year cycle in its gear train — that is, it takes care of non-leap years in three consecutive centuries, as well as the leap year that occurs in the fourth century. Put simply, as long as the watch is consistently wound, it will stay synchronized with the Gregorian calendar and will not require any intervention.

The Ultimate Calendar Complication

It is worth noting that the Gregorian calendar itself is not perfect; it gradually accumulates an error of around one day every 3,030 years. This discrepancy arises from the difference between the calendar year, which consists of 365.2425 days, and the actual solar year, which is approximately 365.2422 days long. Consequently, this implies that the calendar would need to be corrected by one day every few millennia. However, the secular perpetual calendar does not require any adjustments to align with the Gregorian calendar — ever.

First perpetual calendar from Dominique Renaud

Secular perpetual calendars are exceptionally rare in watchmaking due to the hurdle of having to override the month program wheel (48-month or 12-month cam) with notches of varying depths that correspond to the length of each month in a perpetual calendar every 100 years. Consequently, they are frequently subject to patent protection or described in a broader sense, with references to their superior capabilities while avoiding disclosure of the precise methods employed. An upside to this is that unlike a standard perpetual calendar, no two secular perpetual calendar mechanisms are alike with each harboring a plethora of unusual and ingenious solutions of its own.

Although already a rarity, the Furlan Marri’s secular perpetual calendar differs drastically from the few known examples both in terms of its fundamental construction as well as its ease of use. It was the outcome of a collaboration between Furlan Marri, Dominique Renaud, renowned as the co-founder of Renaud & Papi, and Julien Tixier, a talented 30-year-old independent watchmaker.

Andrea Furlan and Al Marri

Andrea Furlan had previously been involved in the design of Dominique Renaud’s DR01, while Julien Tixier and Dominique Renaud crossed paths in 2016 during Dominique’s lectures on his DR01 project. Julien attended these lectures regularly, displaying a keen interest in Dominique’s research. Their friendship eventually led to the “Tempus Fugit” project for Only Watch 2022, an extraordinary gear-based secular perpetual calendar with a personalized countdown function based on one’s probable life expectancy.

Julien Tixier and Dominique Renaud

The Tempus Fugit was conceived by Dominique Renaud and was made by Julien Tixier in his workshop in the Vallée de Joux. The duo reunited this year to create the secular perpetual calendar for Furlan Marri.

Radical Reimagining

While developing a secular calendar is, by any measure, a tremendous feat, the ingenuity of Furlan Marri’s Secular Perpetual Calendar also lies in its stunning simplicity. Unlike a typical perpetual calendar module that consists of over 200 components, the Furlan Marri Secular Perpetual Calendar is composed of merely 25 parts, including a secular assembly made up of only five components. To date, this is the simplest possible mechanical solution to address all the anomalies of the Gregorian calendar in a wristwatch. But as you’ll come to find, mastering simplicity involves understanding the problem and its solutions in real depth before attempting to distill them down to their most basic essence.

In short, embracing complexity is crucial in the pursuit of simplicity.

The most significant deviation from the conventional perpetual calendar design is the use of a circular peripheral rocker instead of a grand lever pivoted on axes that typically extends across the central section of the movement. This offers the advantage of having easy access to any point on the calendar plate while creating more room in the center of the movement. As with a standard perpetual calendar, this peripheral rocker is activated daily by a finger cam that is driven by a 24-hour wheel linked to the motion works.

At the end of each day, it acts on the peripheral rocker, causing it to turn in a counterclockwise direction. The rocker is equipped with a date-change pawl, the travel of which acts on the 31-tooth date star, causing it to advance by one tooth. The date star is pivotably mounted on a date snail cam with a single tooth, which drives a 48-month wheel at the end of the month.

The clever and highly unusual mechanics of the secular perpetual calendar module

As mentioned earlier, the most fascinating part about secular perpetual calendars is how they negate the month program wheel, which lies at the heart of every perpetual calendar, every 100 years. Two renowned secular calendars, namely the Patek Philippe Calibre 89 and the Franck Muller Aeternitas Mega, employed distinct but traditional program wheels. The Patek Philippe Calibre 89 utilized a standard 12-month cam featuring a Maltese cross satellite to manage the month of February, while the Franck Muller Aeternitas Mega incorporated a 12-month cam that operates in conjunction with a leap-year cam. As such, the leap year is already encoded in these systems.

Patek Philippe’s secular calendar mechanism in the Caliber 89 from the original patent. Components No. 10 and 11 are the 12-month cam with a small four-point cam that is fixed to a Maltese cross satelite

Frank Muller’s secular perpetual calendar mechanism from the original patent. Component No. 20 is the 12-month cam and No. 8 is the leap year cam

However, in the Furlan Marri Secular Perpetual Calendar, the change begins with the program wheel itself. While it uses a 48-month cam, its design deviates significantly from the norm. Traditionally, the use of a 48-month cam that performs one revolution in four years, in contrast to a 12-month cam, would mean that the leap year must be encoded in this cam. The 48-month cam in a perpetual calendar is hence always designed with notches of four different steps to correspond to the length of months — 31, 30, 29, and 28 — with the deepest representing 28 days of February, and its full diameter representing 31 days.

But in this case, the 48-month cam was designed with only two depths to encode 31- and 30-day months and is sampled by a feeler pin attached to the peripheral rocker. At the same time, the cam was designed with internal steps rather than external, with four openings for the month of February. These steps limit the travel of the peripheral rocker, enabling an end-of-month beak to engage with a latch on the 31-tooth wheel and move it to different positions when the month comes to an end. At the end of the month, the spring-powered month lever, under tension from a date snail, promptly propels the month star located in the middle, causing it to advance by one position.

Every February, however, the feeler pin passes through completely, extending the amplitude of travel of the peripheral rocker. Thus, the month program wheel is overridden every February, rather than every 100 years as in the case of the Patek Calibre 89 and the Franck Muller Aeternitas Mega.

The 48-tooth wheel on which the month cam is mounted has two driving fingers that advances a 100-year wheel by two positions every four years. This 100-year wheel has 50 teeth, thus completing a full rotation in a century. A rotatable 100-year cam with 25 notches is mounted on it. The low steps of this cam correspond to February with 28 days, while its high steps correspond to 29 days. During a 29-day February, the first driving finger advances the 100-year wheel by one position and a feeler lever bears on the high step of the cam. This feeler has a hook arm that limits the travel of the circular peripheral rocker.

Once February 29 has passed, this hook arm drops to a low level and remains inactive for the next three common Februarys. This is because there are only two driving fingers on the 48-month wheel, and as the second driving finger advances the 100-year wheel, the feeler lever bears on the low step of the cam and remains there to account for the next three common Februarys. When the hook arm drops, the rocker travels further, catching the date snail at an earlier date and forces the date change.

Now, to account for centurial years that are not leap years, as well as the leap year in the fourth century, a Maltese cross mechanism was employed. It comprises a finger cam on the 100-year wheel arbor that gears with a wheel shaped like a Maltese cross, which has four branches and completes a full rotation every 400 years. This Maltese cross is attached to a cam with a pitch circle radius that is greater on one end. During the leap year every four centuries, the high point of the cam acts on a feeler with a retractable tooth, pushing the tooth outwards so that it comes into contact with the amplitude-limiting feeler lever, accounting for a 29-day February in the fourth century.

Its ingenious simplicity is breathtaking. Because the rocker that controls all the individual mechanisms is located on the periphery, it can also double as a corrector. Setting the date is accomplished by rotating the corrector (a blue tab positioned between the lugs) to the right, while turning it to the left corrects the days of the week. On the other hand, the hours and minutes can be adjusted in a conventional manner using the crown.

The entire secular perpetual calendar module is machined, adjusted and decorated by Julien Tixier, while the oscillating weight was cut and beveled by Dominique Renaud. The base movement is the La Joux-Perret G100, a workhorse self-winding movement with a respectable power reserve of 68 hours while maintaining a beat rate of 28,000vph.

Dominique Renaud is seen working on the oscillating mass

The Rest of the Watch

The case is made of rhodium-plated silver, giving it a brilliant white appearance that resembles white gold and platinum while being more affordable. Its proportions are just right, with a diameter of 39mm and a thickness of 11.3mm including the crystal. The case is predominantly brushed, with a polished bezel, while the exposed corrector tab is made of anodized titanium. It is paired with a silver Milanese bracelet, giving it a dash of rakish charm, as is characteristic of Furlan Marri watches. The bracelet was handcrafted by Laurent Jolliet in Le Lignon, one of the last chain makers in Europe. The production of the coils does not involve the use of machines; instead, all the assembly and soldering processes are carried out manually, as is the shaping of the clasp.

Laurent Jolliet, the last Swiss chain maker

The entire process of crafting mesh using hand-wound spiral wire coils is carried out entirely by hand.

The dial is made of anodized titanium with sandblasted chapter rings for the month, day and date. It strikes an incredible balance between clarity and engaging details. The leaf-shaped hour and minute hands are crafted by hand, possessing a form and thickness that cannot be achieved with a stamping machine, as are the blued hands for the day and date displays. The counters are open-worked, revealing the most rudimentary parts of the secular perpetual calendar, namely the day and date mechanisms.

Meanwhile, the most revolutionary aspect of the perpetual calendar — the big secret involving the month and secular program wheels — remains hidden, which only adds to its remarkable stealth.

Lastly, the Secular Perpetual Calendar comes with an estimate of CHF 20,000 to CHF 30,000, which seems woefully insignificant for such phenomenal work. It is worth keeping in mind that secular perpetual calendars, being the pinnacle of perpetual calendars, are either found in grand complications or only obtainable at a prohibitively high cost. It takes a special blend of brilliance and tenacious stubbornness to undertake watchmaking of this caliber at this price. The ability to streamline a broadly unmastered complication is deeply impressive, and to understand it is to love it.

Tech Specs

Pièce Unique Secular Perpetual Calendar by Furlan Marri x Dominique Renaud x Julien Tixier for Only Watch 2023

Movement: Self-winding secular perpetual calendar module developed by Dominique Renuad and Julien Tixier on top of base caliber G100 by La-Joux-Perret; 68-hour power reserve
Functions: Hours, minutes, date, day, month, leap-year indication and secular calendar
Case: 39mm; rhodium-plated silver; hand-engraving on caseback by Coralie Mercier
Dial: Blue anodized titanium dial with hands crafted by Julien Tixier
Strap: Milanese mesh bracelet; rhodium-plated silver clasp made by Laurent Jolliet; additional calf-leather strap provided
Price: Estimate CHF 20,000–30,000

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Bell & Ross x Alessandro Palazzi x Revolution & The Rake Bellytanker Chronograph "Vesper"

$5,250.00

TECH SPECS

Movement	Self-winding caliber BR.CAL-301; 42-hour power reserve
Functions	Hours, minutes, small seconds, chronograph and date
Case	41mm; CuAI7Si2 bronze; water resistant to 100m
Dial	Sunray brushed with applied, gold-plated indices
Strap	Black calfskin; satin polished bronze folding clasp
Limited Edition	Limited edition of 50 pieces

The post In-Depth: The Secular Perpetual Calendar by Furlan Marri x Dominique Renaud x Julien Tixier for Only Watch 2023 appeared first on Revolution Watch.

The Jacob & Co. Twin Turbo Furious, an In-Depth Examination

Cheryl Chia — Thu, 22 Jun 2023 09:00:36 +0000

The Jacob & Co. Twin Turbo Furious, an In-Depth Examination

A closer look at the technical virtuosity behind one of the most electrifying grand complications in modern times.

Jacob & Co.

By Cheryl Chia

Jun 22, 2023

Jacob & Co. has played a serious game in pushing complications in fantastical, larger-than-life directions ever since it set foot in mechanical watchmaking with the Quenttin Tourbillon in 2006. The brand engages in a kind of watchmaking where mechanics are reimagined and interpreted to create maximum visual impact, generating, at times, significant entertainment value. Today, Jacob & Co. is best known for the Astronomia, a series of wrist-mounted amphitheaters that find myriad ways of capturing the heavens above. But, the Twin Turbo Furious was the vehicle in which the company first applied its conceptual, maximalist streak to traditional grand complications, and the result is something that is without direct comparison in watchmaking, despite it being visually and spiritually reminiscent of the sort of high-octane, high-risk watchmaking that took root in the early 2000s.

Quenttin Vertical Tourbillon
Astronomia Tourbillon White Gold

Launched in 2018, the Twin Turbo Furious is nominally a minute repeater with a chronograph and double toubillons. However, each complication is of an exotic variety. The minute repeater chimes the time digitally, making it a decimal minute repeater. The chronograph is a single-pusher chronograph with a reference time differential indication, and lastly, the pair of tourbillons are flying, triple-axis and high-speed. Conceived by Le Cercle des Horlogers, the movement was masterfully constructed to accommodate the radically executed, wedge-shaped case, and as a result, has a highly unusual architecture that is worth a deeper dive.

Jacob & Co. Twin Turbo Furious, 2018

Twin Flying Triple-Axis Tourbillon

Since the advent of the 21st century when the resurgence of interest in mechanical horology sparked the rebirth of the tourbillon, tourbillons and all its exotic descendants have grown more prevalent. Double tourbillons — in the strictest sense, with two balances and escapements — alone, have been accomplished by a handful of brands as diverse as Greubel Forsey, Roger Dubuis and Cecil Purnell.

However, the basic principle of the Jacob & Co. Twin Turbo Furious differs slightly from every other known configuration and for which a patent was issued. In a standard double tourbillon watch, both tourbillons are driven by a single barrel and gear train, along which a differential splits power to each tourbillon while averaging out their errors in rate to produce a single averaged deviation. However, visible on the back in the Twin Turbo Furious, each tourbillon is actually driven by its own gear train and mainspring barrel, arranged linearly in a parallel configuration with their respective third wheels sporting an intricate, skeletonized pattern.

Twin Flying Triple-Axis Tourbillon

As such, a differential cannot be applied to such a design. Instead, both tourbillons are mechanically coupled by means of a friction clutch. Hence, one regulating organ is able to influence the rate of the other directly so as to oscillate at the same frequency, thereby averaging their errors in rate. In so doing, each oscillator becomes less susceptible to errors as compared to one operating in isolation. Both wheels in the clutch are only driven together by friction when the rate of one oscillator varies from the other. Each barrel offers a power reserve of 50 hours, with both unwinding at the same time and speed. Meanwhile, the hands are indirectly driven by the gear train without the chronograph. In other words, the timekeeping gear train is isolated from the chronograph to maintain accuracy when the chronograph is in use. The solution of providing each triple-axis tourbillon with its own energy source, as opposed to having a single mainspring drive two parasitical mechanisms — three, including the chronograph — also helps the watch maintain a respectable power reserve. Both barrels are wound via an unusual crank handle with the crown in the neutral position.

The case of the Twin Turbo Furious is topped by a dramatically curved sapphire crystal that widens and rises at the base to accommodate the three-dimensional extravaganza of the tourbillons, with a power-reserve display situated in between them. As opposed to a traditional tourbillon that rotates on a single axis to compensate for errors in rate in all possible vertical positions, the triple-axis tourbillon rotates simultaneously across three different axes. The combined axis of the three cages results in the escapement being rotated in a seemingly random orbit, which exposes the balance wheel to a greater variety, if not almost all positions and averages its timing errors. The spectacle is enhanced by the speeds at which each tourbillon cage is made to rotate. Beginning with the innermost cage, each of them completes a revolution in 24 seconds, eight seconds and 30 seconds respectively. Collectively, the three cages will return to their original positions after 120 seconds — the lowest common multiple of the periods of each cage.

The carriages in later versions of the Twin Turbo Furious would be geared to run at a comparatively languid and fluid pace of 24, 48 and 180 seconds respectively per revolution, allowing their intricacy to be better admired.

Chronograph with Reference Time Differential

At the same time, the massive skeletonized third wheel in the gear train to the right when viewed from the back, also meshes with the pinion of the drive wheel of the chronograph — although in later versions, a separate, smaller wheel is superimposed on the third wheel to drive the tourbillon.

The chronograph relies on a classic horizontal coupling system that is visible right at the heart of the movement. The clutch lever that connects the drive wheel to the chronograph wheel is remarkably long and made up of just a single piece with an intricate skeletonized form. It goes between the chronograph seconds wheel and the strike train above before extending downwards over the clutch wheel. This unique arrangement of gears allows the chronograph seconds wheel, minutes wheel and driving wheel to be supported by the same bridge, which is shaped like an arrowhead to maintain an overall symmetry in movement design.

Most unusually, the chronograph is connected to a reference time differential indicator. It was inspired by pit board timekeeping panels once used in motor racing to communicate the difference between the reference lap time and actual lap time to drivers. The reference time is set via the crown in the first position and displayed in two adjacent apertures at six o’clock on the dial. The larger digit shows the minutes, and the aperture to its right indicates the seconds.

The chronograph relies on a classic horizontal coupling system

Once the chronograph is started and stopped, the chronograph hand then indicates the time difference between the recorded time and the reference time on the rotating “pit board” wheel. A positive difference is shown with red numerals on the wheel, while a negative difference is in yellow.

Decimal Minute Repeater

The third complication is a decimal minute repeater, a modern take on the traditional repeater that is rather apt for such a progressive timepiece. First introduced by Kari Voutilainen in 2005, a decimal minute repeater is a more intuitive acoustic system that chimes the minutes in units of tens and ones after the hours instead of sounding the quarters and minutes.

Visible at 12 o’clock at the back of the watch is the repeating barrel that is flanked by hammers that pivot on staffs. The larger hammer on the right hits a low-pitch gong for the hours while the smaller hammer hits a low-pitch gong for the minutes. When the slide on the left side of the case is pushed, it charges a small spring within the repeater barrel, and when released, energy is dissipated to power the strike train. Visible at the end of the strike train is a governor, which has two arms that spread out to control the speed at which the spring unwinds, hence setting the tempo of the chimes.

As with most chiming watches, the snail cams and their respective racks that are responsible for translating the motion of the hands to sound, is located on the dial side and thus can’t be seen. The snail cams are connected to the motion works on the dial side, while part of the hour rack projects from the caseband and fits into the slide. And as is the case with all minute repeating watches, the strike train and the main gear train in the watch are by no means directly connected, even if it appears to be otherwise from the caseback.

The shape and voluminous size of the case, along with the expansive sapphire crystal, ensure that the gongs have more to work with in terms of surfaces to amplify and enrich the sound. Thus, it is a chiming watch that truly delivers even if its sonic and chronometric performance is peripheral to its sheer audacity and entertainment value.

Jacob & Co. Twin Turbo Furious in rose gold and blue titanium
The Twin Turbo Furious Sapphire

Various iterations of the watch have since been released with the most memorable being the fearsomely beautiful Twin Turbo Furious Bugatti La Montre Noire which featured a black gold case that was completely covered in black baguette-cut sapphires, and the Twin Turbo Furious Sapphire Crystal which puts the entire movement on show.

Artful Mechanics

Without a doubt, the Twin Turbo’s shrill showmanship and aggressive design are intended to astound, but it will prove equally intellectually rewarding to those who search beyond this instant of theatricality.

The Twin Turbo Furious finds no immediate equivalent in watchmaking. Tourbillon chronographs are rather rare to start with, despite each being a relatively common complication on its own. And there are a few reasons for this. A tourbillon is driven on a fixed fourth wheel, doubling as a seconds indicator, while a chronograph is driven off the fourth wheel, which itself displays the running seconds, thereby necessitating solutions in gear arrangement that are less than straightforward. They are also limiting in terms of design, with the most obvious and intuitive configuration being a bi-compax layout with a tourbillon at six o’clock, which at the same time is not plain as day to achieve due the previous reason. But most of all, it demands considerable mastery in energy management. Apart from this, the Twin Turbo Furious adds a decimal minute repeater and a second tourbillon, which very unusually has its own gear train and barrel and is linked to the first via a coupling system. Each complication is rare and unusual in and of itself, which makes the watch even more unique as a whole, and equally so in the way they are amalgamated.

Jacob & Co. Twin Turbo Furious Black

With a starting price of USD 550,000 for the version with a black DLC titanium and forged carbon case, the Twin Turbo Furious packs a whole lot of punch for the money.

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TECH SPECS

Movement	Self-winding caliber FBN 229.01 with natural escapement; 72-hour power reserve
Functions	Hours, minutes and small seconds
Case	40mm; stainless steel; water resistant to 30m
Dial	Verdant green, with sector track; applied, white rhodium treated gold Arabic numerals and hour markers
Strap	Brown calf leather with Alcantara lining, stainless steel pin buckle; additional Milanese bracelet in stainless steel
Limited Edition	Limited edition of 15 pieces

The post The Jacob & Co. Twin Turbo Furious, an In-Depth Examination appeared first on Revolution Watch.

The Out-of-This-World Jacob & Co Astronomia

Revolution — Mon, 24 Apr 2023 17:00:51 +0000

Jacob & Co. is widely recognized for its jewel-encrusted timepieces and much loved by high-profile celebrities in entertainment and sports, as well as seasoned collectors who appreciate their creativity and bravura approach.

The brand has taken its distinct style and applied it to ever-more-complicated watches, with the aim of evolving their offering in typically over-the-top fashion. One of the brand’s earliest technical marvels was the Astronomia, and its debut was quite eye-opening. It features a magnificent sapphire-crystal dome framing an architectural movement, creating an expansive feel with its vertical tower and horizontal arms. And, as one would expect from a Jacob & Co. timepiece, some of these arms were adorned with extra-large gemstones.

The first-generation Astronomia Tourbillon from 2014

Resembling planets rotating in space, the glittering gemstones immediately catch the eye — so much so that you may miss the impressive mechanisms around them. Reducing this watch to the number and weight of stones would be a mistake, as a closer examination reveals the clever mechanics and playful design of the watch, especially in the construction of the tourbillon and the time display that seem to float in space. These qualities arguably demand recognition, and are just as innovative as the mechanisms created by independent brands such as URWERK and MB&F.

The concept of the Astronomia also resonates with me on a personal level, as the moving components above the dial remind me of the orreries I found fascinating as a child in museums and science galleries. As I gained a deeper understanding of its inner workings, I came to appreciate the elegance of its conception, and I particularly like how the brand maintains its unique style while pursuing technical excellence.

The Origins

Since its debut at Baselworld in 2014 with the Astronomia Tourbillon, Jacob & Co.’s Astronomia series has spawned numerous iterations with increasingly lavish decorations or complex constructions. However, the original model’s planetary-style movement design, with arms carrying the movement parts around the dial, remains a standout feature. The satellite display has served as the foundation for many of the follow-up models, demonstrating both the continued popularity of the series and the ingenuity of its movement design.

The original Astronomia Tourbillon, but in a later version

The achievement of Astronomia is less surprising once you know its history. It all started with the founder of the brand, Jacob Arabo, who wanted to create something truly remarkable — something that would set his brand apart from the competition. His vision was to design a watch with a three-dimensional movement that could be appreciated from every angle.

Jacob knew he needed an exceptional talent to bring his idea to life. That’s where Luca Soprana, the founder of Ateliers 7h38, came in. Luca, a fourth-generation watchmaker, learned his craft by working in his family’s workshop and gradually building his expertise, as well as working with independent watchmaker Vianney Halter and several other brands before founding his own workshop.

Jacob Arabo

Luca Soprana

In 2014, Jacob and Luca refined the initial idea and developed a concept movement that not only has three-dimensional components, but also glides around the dial with varying motions. The view of the watch is remarkable — like watching a galaxy of planets orbiting in space. Considering the level of difficulty involved in realizing such an ambitious concept, the fact that the Astronomia boasts clean and uncluttered mechanics, is a testament to the amount of thought that went into its development.

Moreover, the Astronomia’s case is a feat of engineering and aesthetics, utilizing an unconventional construction with more sapphire than gold, thus allowing for an uninterrupted view of the intricate components. The case design really does play a pivotal role in the watch’s overall appeal and distinctiveness.

Although Luca played a key role in conceptualizing several Astronomia timepieces, including the Astronomia Maestro Minute Repeater, the project faced challenges that Ateliers 7h38 had to navigate. Luca, being a traditional watchmaker, relied heavily on manual processes during the prototyping phase, which included hand-filing and cutting the components. As a result, when handling Luca’s prototype, it is evident that it is a handmade piece, according to Jacob’s master watchmaker, Bahman Tagharrobi. While this approach had its merits, it also meant that Luca wouldn’t be able to produce the Astronomia movement at scale. Jacob wasn’t content to merely showcase a prototype and then go quiet (as has happened with many concept watches that never made it to production). He was determined to make the Astronomia accessible to enthusiasts and produce 10 to 15 pieces per year, which was beyond Luca’s capacity.

The Astronomia Maestro Worldtime with a carillon minute repeater

Consequently, Jacob enlisted the help of Concepto, another expert in complications, to complete the manufacturing of the Astronomia series. Concepto’s larger team and experience in supplying for high-end brands like Bulgari, Louis Moinet and Breitling made them the ideal choice for the job. It was also the right time for Concepto, as they were keen to take on more challenging projects, and the Astronomia fit the bill perfectly. Bahman noted that Concepto’s expertise in prototyping allowed them to rework the movement, resulting in a more affordable construction (compared to the handmade prototype) that makes commercial sense for production.

Today, Concepto is responsible for producing almost the entire Astronomia series, including the latest Astronomia Revolution. The only exception is the Astronomia Maestro Minute Repeater, which was developed by Luca’s Ateliers 7h38 and produced by Le Cercle des Horlogers, a complications specialist that is also responsible for the recent Biver Carillon Tourbillon.

The latest Astronomia Revolution features a one-sixth-of-a-second remontoire, making it the fastest of its kind in the world

Reading the Astronomia Tourbillon

The Astronomia is an impressive mechanical creation that rotates around the dial, resembling a miniature orrery on your wrist that you can enjoy at any time.

Despite its intricate appearance, the Astronomia is ultimately a timepiece, so telling time is its primary function. To explore how to read the Astronomia, let’s take the Astronomia Tourbillon, the inaugural model, as an example.

The current generation of the Astronomia Tourbillon in rose gold

Fortunately, reading the time on the Astronomia is relatively simple. It features conventional hour and minute hands on a skeletonized subdial on one arm, while the seconds are indicated by a rotating globe on the other satellite arm. This design allows you to quickly see important information while adding a touch of creativity to less essential details.

The opposite arm of the dial showcases the tourbillon regulator, while the other side of the rotating globe has a one-carat diamond. Although these components don’t tell time, they’re fascinating to observe, particularly the tourbillon, which rotates around three axes: one-minute rotation around the cage’s center, five-minute rotation around the arm’s center, and 20-minute rotation around the dial, thanks to the carrier.

While the Astronomia boasts an intricate design, winding and setting it is actually quite easy. You can hand-wind the movement using the crown on the back, which has a tab to make it more manageable to operate. Setting the time is accomplished with a similar mechanism next to the winding crown.

Understanding the Astronomia Tourbillon

With the Astronomia, a traditional watch movement is reimagined and transformed into a spectacle of three-dimensional design. The result appears to capture a moment frozen in time, like an exploded diagram used for illustration purposes, resulting in immense vertical and horizontal extension. Almost everything is located above the dial, except for the barrel and winding mechanism, which remain hidden underneath.

The movement is built around the barrel, which provides the watch with a 60-hour power reserve. The barrel sits at the center of the movement and below the dial, with arms extending from the center.

At the heart of the Astronomia movement lies a crucial component: the carrier. This central structure serves as a bridge that connects all of the intricate arms and mechanisms that make up the timepiece. What’s notable about the carrier is its lightweight titanium construction, which allows for minimal energy consumption without sacrificing durability.

As the carrier rotates around the dial every 20 minutes, it brings all of the arms along for the ride. This creates a dynamic and interactive experience for the wearer, who is constantly able to discover new positions and configurations of the components. But the rotational movement isn’t just for show — it serves a crucial purpose in the functioning of the timepiece by helping to transfer energy from the barrel to each of the arms.

The transfer of energy is achieved through a tiny component called a pinion, which is the smaller of the two meshing gears that usually serves to change speed due to the gear ratio. Here, the pinions are connected to the components of the arm while being vertically meshed with a fixed central gear. When the carrier rotates, the pinion is forced to move along the central gear, thus transferring the movement into the arm. This is especially evident in the two simpler arms, where the pinion is obvious, and the rotational movement of the globe and diamond is the same as the pinion.

The most complex of the four arms is that with the tourbillon regulator. The tourbillon is a double-axis tourbillon, but if you consider the movement of the carrier that takes the entire tourbillon assembly around the dial once every 20 minutes, it becomes a triple-axis tourbillon.

What I find fascinating is the clever facilitation of the two axes of rotation in the tourbillon. When the pinion turns, it causes the entire tourbillon and balance assembly to rotate around the arm. However, this movement does not transfer any energy to the tourbillon itself, as it only involves the component rotating around the arm every five minutes. On the opposite side of the pinion is a large, vertical gear that remains fixed in place. And here comes the clever part: a horizontal wheel, positioned underneath the tourbillon cage, meshes perpendicularly with the vertical gear. Since the vertical gear remains stationary, the horizontal wheel is compelled to rotate on it, transferring movement to the tourbillon and driving the cage to rotate around itself every minute.

The arm with the dial works a little differently. Instead of using a pinion that meshes vertically with the gear above the barrel, it uses a horizontal gear that meshes with the central gear. This makes sense since the dial doesn’t require rotation around the arm for time telling. The horizontal gear that meshes with the central gear drives the minute and hour hands via the motion works, which can be seen under the skeletonized dial. Additionally, the arm with the dial is equipped with a differential gear system that enables the dial to remain oriented correctly regardless of the arm’s movement.

Horizontal gears for the time display

The speed of rotation, meanwhile, is coordinated within the movement. Despite its complex appearance, the Astronomia operates on the same fundamental principles as a standard watch. The balance wheel and escapement work together to control the rate of unwinding of the mainspring barrel, which governs the speed of the gear train. To put it differently, energy flows from the barrel to the balance wheel, while speed feedback goes in the opposite direction.

Now, while most mechanical watches are designed with many gears that can make them appear cluttered, the Astronomia takes a different approach. It features a central wheel that is particularly clever, since it not only allows the barrel to transfer energy to all ends, but also plays a key role in coordinating the rotation rate as part of the gear train between the barrel and balance wheel. This elegant design ensures that the Astronomia’s movement remains clean and uncluttered.

While Jacob & Co.’s approach to watchmaking may not appeal to those with more conservative tastes, the brand’s horological innovations are making everyone sit up. Studying the intricate inner workings of the Astronomia is a fascinating exercise. Furthermore, the brand’s creative approach to watchmaking offers a refreshing alternative to the conventional timepieces on the market. As the world of watchmaking continues to evolve and challenge established norms, only time will show Jacob & Co.’s true legacy.

Standout Variations

The Astronomia watch series boasts a spacious case and airy movement architecture, which provides a canvas for incorporating diverse complications and artisanal expressions. This feature has led to the creation of a range of impressive models.

One of the most fascinating Astronomia models is the Maestro Minute Repeater, which features a carillon repeater that is more elaborate than standard chiming mechanisms. It uses three gongs instead of two, providing a richer chime with three notes for the minutes. The gongs are strategically placed around the movement, providing a clear view through the sapphire window that encases the case. To further enhance the auditory experience, the Maestro employs cathedral gongs that circle around the movement twice, resulting in an amplified sound. Furthermore, the Maestro model retains the hallmark triple-axis tourbillon, supported by a faster carrier movement that completes a revolution around the movement every 10 minutes, an improvement over the standard 20 minutes.

Two of the three gongs in the carillon minute repeater

Another standout timepiece is the Astronomia Casino, which features a unique roulette automaton with a wheelhead that spins freely upon activation, while a ceramic ball bounces around before eventually landing on a lucky number. Unlike earlier roulette watches, such as the Franck Muller Las Vegas or Azimuth Sp-1 Roulette, which use a spinning hand to point at the dial, the Casino’s spinning wheelhead with a free-running ball creates a more dynamic and compelling interpretation of the roulette watch.

The Astronomia Casino comes with a spinning wheelhead that has a free-running ball

The Latest and Greatest

Finally, Jacob has just unveiled its latest iteration, the Astronomia Revolution, which achieves two milestones for the brand. First, the Revolution boasts a sleek design that showcases its most important features, namely the architectural movement, and is arguably the purest expression of the Astronomia idea to date.

Second, the mechanics have been thoroughly upgraded, with a strong emphasis on extreme speed. In the original Astronomia, the central carrier rotated around the dial once every 20 minutes. In later iterations, this period was halved to 10 minutes. But in the latest Astronomia Revolution, the rotational speed of the carrier has been dramatically increased to one revolution per minute, equivalent to a standard tourbillon. As a result, it is the most visually dynamic Astronomia yet. Moreover, thanks to the one-minute revolution, the entire movement also doubles up as a seconds hand, marking the first time an Astronomia boasts a rotating carrier that also tells time.

Another technical improvement, and certainly the more significant, is the new remontoire system that’s the world’s fastest — it charges and discharges six times per second. That’s extremely fast considering the typical rate of discharging is once every second. This means that the constant-force mechanism lives up to its name, quite literally, delivering an equal amount of energy to the balance wheel at every single beat.

Thanks to the assistance of Concepto, the new patent-pending remontoire system (not shown in the press images) consists of two primary components. First, a remontoire spring stores a small amount of energy that is sufficient to advance the escape wheel by one tooth. Second, a four-armed, star-shaped wheel known as the “whip” regulates the recharge of the remontoire spring. The remontoire spring is linked to the fourth wheel, which powers the tourbillon cage from below. Importantly, there’s a buffer between the remontoire and the balance wheel, as it is not directly connected to the escape wheel, to prevent any disturbances caused by the high-speed device.

The tourbillon assembly of the Astronomia Revolution

And the dial

But the remontoire is far from a high-speed gimmick; it’s actually crucial to the watch’s operation.

The one-minute central carrier is an energy monster that requires a significant amount of power to keep it running. Despite having twin large barrels, the watch’s short 36-hour power reserve indicates the amount of energy consumed by the carrier. However, having two large barrels means that the escapement is locking and unlocking with significant force, which is too “violent”, according to Bahman. He also noted that the original prototype felt like an old pocket watch that was wound up too much, causing everything to shake and resulting in poor timekeeping. With the acceleration and deceleration at the escapement being profoundly great, the impact that occurs toward the end of the gear train is too large and negatively affects timing. Therefore, a constant-force mechanism is necessary to act as a buffer, dividing the large amount of torque into smaller portions to deliver to the escapement.

One might wonder why the watch doesn’t use a typical one-second remontoire. The brand explains that even a spring that stores enough energy to drive the escapement by one second is still too violent for the escapement. Therefore, the energy needs to be broken down into the smallest possible portion, resulting in a system that delivers energy to the balance at every “tick” and “tock”. Since the watch runs at 3Hz, with six back-and-forth movements of the balance per second, the remontoire must charge and discharge six times per second, resulting in the world’s fastest 1/6th-of-a-second system. This is what makes watchmaking so fascinating, as it pushes boundaries to overcome actual problems, leading to genuine, innovative and interesting solutions.

The post The Out-of-This-World Jacob & Co Astronomia appeared first on Revolution Watch.

The Basics and Beyond: Perpetual Calendar

Cheryl Chia — Mon, 24 Apr 2023 06:26:34 +0000

The Basics and Beyond: Perpetual Calendar

One of the most hallowed complications in watchmaking and the ingenuity involved in simplifying their complex makeup.

Technical

By Cheryl Chia

Apr 24, 2023

The calendar has, across the gulf of centuries, given our species a sense of the big picture, of dailiness and eventfulness as well as a vital historical consciousness. By contrast, time measured by the clock seems to be abstracted from the motion of the universe, as if time was granular or a series of short, disjointed phases rather than continuously hastening the frantic world on with each tick.

In our modern technological age, the calendar serves as a connection to the natural world, whereby the rhythms of the earth and sky coordinate with that of human life. Naturally, a mechanical watch that denotes the progress of the calendar has to embody these cosmic rhythms in gear patterns and ratios, namely the speed at which the Earth rotates on its own axis, forming the day, the Moon’s orbit around the Earth, giving us the month, and finally, the Earth’s orbit around the Sun, which marks a year.

The highest order of such watches is the perpetual calendar as it needs to accomplish a high degree of automation, namely a yearly reiteration, hence having to obey the dictates of the Gregorian calendar in which each leap year has 366 days instead of 365, giving February 29 days instead of the common 28. This means that the mechanism has to correctly care for all irregularities of the calendar, acting at the end of each month, changing itself to the first day of the following month, sometimes after 30 days and other times after 31 days, changing once a year on the 28th day of February and finally, extending February by a day every four years. The complexity of encoding this nest of rules makes the gear train of a perpetual calendar one of the most intricate, perhaps second only to that of a minute repeater — both of which, with much irony, are driven by the humble motion works that spell out the time in every watch.

The instantaneous date mechanism in the H. Moser & Cie. Perpetual Calendar

However, a perpetual calendar, contrary to the optimism expressed in its name, is not everlasting. By design, a perpetual calendar omits the one rule that makes a calendar Gregorian rather than Julian and that is, centurial years are only leap years if they are divisible by 400. The mechanism will interpret the years 2100, 2200, and 2300 as leap years when in fact they are common years. In other words, a perpetual calendar will recognize the length of every month irrespective of whether it contains 28, 29, 30 or 31 days until the year 2100 before it requires a manual intervention. It is worth noting that the only kind of calendar watch that can account for this principal anomaly is the secular perpetual calendar, making all regular perpetual calendars, more strictly, Julian calendars.

Perpetual calendars are predominantly executed in one of three formats. It can be designed with a 48-month cam that encodes the length of the months in a four-year cycle with notches of varying depths, a 12-month cam which functions the same way but makes a revolution once a year while working with a separate leap year cam, or a 12-month cam with an integrated Maltese cross satellite to manage the month of February. At the heart of each format is a grand lever that advances the date one day forward every day at midnight and is built to automatically advance past the additional days at the end of months shorter than 31 days.

From top: An example of a perpetual calendar with 12-month cam; The 12-month cam (30) works in conjunction with a leap year cam (29)

Most perpetual calendars are modular in construction in that the calendar mechanism is fitted on an additional plate rather than being an integral part of the movement. There are a handful, however, wherein the baseplate was designed to accommodate calendar indications that extend to the back of the watch.

48-MONTH CAM

The gear train that encodes the units of the date — day, month and year — are derived from the motion works, specifically the hour wheel of a watch. This makes the gear train of a perpetual calendar mechanism, like the motion works itself, a reduction train. As illustrated in the diagram, driven by the motion works below the calendar plate is a 12-hour wheel that drives a 24-hour wheel. Affixed to it is a finger that indexes a moon gear, typically with 59 teeth to account for two lunar cycles, advancing it by one notch every 24 hours. At the same time, this finger also comes into contact with the arm of a grand lever, lifting it every 24 hours. The grand lever then pivots, and another arm engages a seven-point day star wheel, moving it forward by one step. At this point, a beak on the grand lever also comes into position to actuate a 31-tooth date star wheel, advancing it by a notch.

All this time, the third arm of the grand lever bears on a 48-month cam that is driven at the rate of one rotation in four years. This cam governs the travel of the grand lever. It consists of notches of varying depths, four specifically to correspond to the length of months — 31, 30, 29, and 28 — with the deepest representing 28 days for February and its full diameter representing 31 days. Each slot increases or decreases the length of travel made by the grand lever and the arm that drives the date star. This enables the arm to advance the date wheel further, when necessary, by several days at once so that it can jump from 28 to 1 at the end of February, for instance.

The grand lever, thus, pivots varying amounts based on the month — further for short months and lesser for long months. At the end of the month, the fourth arm on the grand lever locks into a date snail cam and forces the date change. Hence, if the grand lever pivots further, it catches the snail cam at an earlier date.

The date star carries a finger that engages a 48-month wheel at the end of every month. An intermediate wheel affixed to it then drives a 48-tooth wheel, consequently rotating the 48-month cam.

It is difficult to determine which format of program wheel is used by looking at the dial as there are ways to achieve a desired design regardless of which is used; watches that adopt a 48-month cam do not necessarily have a 48-month indicator. Known examples that use a 48-month cam system are any of Patek Philippe’s three- register perpetual calendars.

12-MONTH CAM WITH SEPARATE LEAP YEAR CAM

A 12-month cam differs primarily from a 48-month cam in having a rotation speed of one turn per year. As such, a leap year, which occurs once every four years, cannot be encoded in this cam. It consists of notches of only three varying depths, accounting for 31, 30 and 28 days. To account for February 29, the 12-month cam works in conjunction with a separate leap year cam.

Patek Philippe Perpetual Calendar 5327G (left) and Perpetual Calendar Chronograph 5270J (right). As a rule of thumb, all Patek Philippe’s perpetual calendars with triple counters employ a 48-month cam while other configurations rely on a 12-month cam (Image: ©Revolution)

In such a configuration, the 12-month cam is sampled by an arm of the grand lever while a second arm bears on a leap year cam. The latter is co-axially mounted on the 48-month wheel, which completes one rotation in four years. The leap year cam has a large plain section that corresponds to a conventional 28-day month of February in three consecutive years, followed by a high step that takes care of a 29-day month. During a leap year, the lever bears on the high step and this prevents the first arm from reaching the full depth of the February notch in the 12-month cam, thereby overriding it.

This limits the travel of the grand lever which then catches the date cam later and advances three steps at the end of the month.

12-MONTH CAM WITH MALTESE CROSS SATELLITE

An alternative to having a separate leap year cam is to incorporate a Maltese cross system in the 12-month cam to manage the month of February. In this format, the 12-month cam is affixed to the month star wheel and consists of two depth profiles, with the full diameter corresponding to months with 31 days, and shallow recesses that take care of months with 30 days. The cam features a cutout where February ought to be and in its place is a leap year cam. The latter has four points — three identical points of the same height and one point that is longer. This cam is fixed to a Maltese cross that is pivoted on the month star.

The 12-month cam with a satellite wheel to manage the month of February

The Maltese cross, like that used as a stopwork, rotates around a finger cam that is mounted on the month star. When the finger enters a notch in the Maltese cross, it forces it to make a 90-degree rotation. This continues such that the longer, protruding side is exposed to the grand lever in the fourth year, limiting its travel to account for February 29.

ADJUSTMENT VIA CORRECTORS

While a perpetual calendar only requires a correction after every full century when the Gregorian calendar omits a leap year, like a regular watch, it comes to a halt when the mainspring winds down. Thus, correctors are installed so that the day, date, month and moonphase can be manually adjusted with little pushers set into the caseband using a stylus.

Each indicator has its own corrector in the form of a lever that overcomes the tension of a spring when it is depressed, enabling adjustments to be made forward. When changing the month, a lever lifts the grand lever, so the 48-month cam is freed and the corrector lever advances a pinion, which drives the 48-month wheel. The day star can be set independently with its own pusher and corrector lever as well as together with the date via a second pusher that acts on the grand lever.

BREAKING THE MOLD: IWC DA VINCI PERPETUAL CALENDAR

The complex, notably three-dimensional construction of a perpetual calendar characterized by levers and springs results in high cost in manufacturing and assembly. Hence, for a long time, perpetual calendars remained the preserve of top watchmaking companies the likes of the holy trinity.

But in 1985, a new wind began to blow when IWC introduced the Da Vinci, the first perpetual calendar in which all indications can be adjusted via the crown. Designed by the firm’s legendary head watchmaker Kurt Klaus, the calendar mechanism did away with corrector levers and reduced the number of intermediate components by having each display wheel drive the next directly, greatly reducing part count. As such, the movement was notably compact and slim while the calendar display was remarkably complete with the addition of a full four-digit year.

The ingenious perpetual calendar module developed by the legendary Kurt Klaus

The module was characterized by a uniquely shaped grand lever, which is driven back and forth by a drive wheel linked to the motion works. It has a feeler arm that samples a 48-month cam while its ring-shaped arm has a shift pawl that advances a 31-tooth date ratchet wheel daily. Instead of having a separate finger cam, a tooth that extends further outward radially on the date ratchet wheel advances the 48-month wheel directly.

IWC Big Pilot’s Watch Perpetual Calendar Edition “Rodeo Drive”

The ring-shaped arm has an additional pawl that rides against the date cam. As with a standard perpetual calendar, this pawl catches the cam earlier or later, as governed by the depth of penetration in the 48-month cam, and forces the date change. At the end of a 28-day February, for instance, the swing of the grand lever leads to a turning of the date wheel by three teeth by the pawl and the turning of another tooth by the shift pawl, thereby progressing by four teeth to March 1.

In effect, the date wheel indexes the 48-month wheel directly and the latter drives a 12-month wheel on which the month hand is mounted. The 12-month wheel has a finger affixed to it that engages a pair of co-axially mounted intermediate wheels of the same diameter and pitch. The first wheel has 10 teeth while the second has a single tooth. They mesh with another pair of identical co-axially mounted wheels to achieve a digital year display. One gears with the 10-tooth wheel, giving us the year and the other, the single-tooth wheel, forming the decade wheel. Thus, the year wheel is moved once a year by one tooth and the decade wheel is advanced once every 10 years by one tooth.

IWC Portugieser Perpetual Calendar 42

Along the periphery of the decade wheel is a protrusion that engages the horizontal recesses in a century slide such that after each revolution of the decade display ring, the century slide is moved further by an amount equal to one recess. A detent device consisting of a disk that is tensioned by a spring into the edge of the recess secures it in place after each displacement.

The daily swinging motion of the grand lever also advances a day star by one tooth. The day star, pivotably mounted on a moonphase wheel, drives a reduction train at a ratio of 8.4375:1, enabling the moon disk to make one rotation every 59.0625 days.

REINVENTING THE WHEEL: ULYSSE NARDIN PERPETUAL LUDWIG

Following IWC’s breakthrough, developments that followed the same path of simplicity slowly began to emerge. The most significant was the Ulysse Nardin Perpetual Ludwig launched in 1996 to mark the brand’s 150th anniversary.

The watch was named after Ludwig Oechslin, a Vatican clock restorer and polymath, who spearheaded the rebirth of Ulysse Nardin, along with its visionary owner, Rolf Schnyder. The Perpetual Ludwig was the first perpetual calendar that enabled forward and backward date adjustments over a single crown.

The landmark Ulysse Nardin Perpetual Ludwig can be adjusted both forwards and backwards via a single crown

This was made possible by eliminating the conventional 48- or 12-month cam with deep notches, which immediately quashed the need for a grand lever. However, this is not to say that the resulting mechanism was simple. On the contrary, its structural simplicity — composed of nothing but precise gearwork — is exceedingly hard to achieve, and the genius by which the solution was produced only inspires awe.

At the heart of the mechanism is a pair of co-axial wheels — a 31-tooth date wheel that completes one revolution per month and a co-axial fixed wheel. The date wheel is driven forward by a 24-hour wheel, which, as with a standard perpetual calendar, is controlled by the hour wheel. However, this 24-hour wheel comprises of two stacked wheels — the first wheel with a single long tooth to advance the date wheel by one tooth at the end of months with 31 days and the second wheel, superimposed on the first, with three successive long teeth to take care of months with 30, 29 or 28 days. The wheels are offset such that the long tooth of the first wheel is immediately followed by the three long teeth of the second wheel to advance the date wheel by additional steps at the end of months with less than 31 days.

Ludwig Oechslin’s perpetual calendar mechanism from the original patent

As the date wheel turns, a system of planetary gears rotates around the fixed wheel. It consists of three wheels — the first for months with 30 days or less, the second for February and the third for leap years. They are rotatably mounted on individual axles on the date wheel. Each of the three wheels have one or more teeth that are longer than the others — four (out of 24) teeth on the first wheel, one (out of 24) on the February wheel, and three (out of eight) protruding teeth on the leap year wheel. The longer teeth protrude at the periphery of the date wheel as the latter rotates and are retracted inwards the rest of the time. As the longer teeth emerge on periphery at the end of the month, they come into contact with three additional teeth on the 24-hour wheel to generate the additional steps on the date wheel at the end of a month of less than 31 days.

The date wheel itself is mounted on a large finger cam, which indexes a pinion at the end of the month. This pinion in turn drives the month wheel.

As a result of being entirely made of gears, the calendar can be adjusted both forward and backward and is eminently more resistant to shocks, making it more robust.

THE MOST ADVANCED PERPETUAL: H. MOSER & CIE. PERPETUAL CALENDAR

In 2005, H. Moser & Cie. went a step further and developed an instantaneous perpetual calendar that enabled forward and backward adjustments of the date via a single crown. Aside from being predominantly made of gears, Moser’s perpetual calendar introduced two more factors to the equation that made its construction inherently unusual — a centrally-mounted month hand and an instantaneous date wheel — hence, differing drastically from Ludwig’s invention. While the resulting mechanism is exceedingly simple and practical, it required nothing less than the genius of Andreas Strehler, an independent watchmaker who is best known for having developed the most precise moonphase indicator in the world with an error of only one day in 2,060,757 years.

The date mechanism consists of two disks, arranged one over the other and operates in a relay. The top date disk bears the date numerals “1” to “15” followed by an aperture, through which the bottom disk with “16” to “31” can be read. In the second half of the month, the top disk is stationary with the aperture positioned at three o’clock and the bottom disk advances. At the end of the month, the top disk makes a single jump to the first day of the following month.

The “Flash Calendar” instantaneous date-change mechanism

A closer look at the unusual switching system on the bottom disk that acts on a series of four latches on the circumference of the top disk

This is made possible by a highly unusual switching mechanism that indexes the top date disk out of its stationary position at the end of any given month. It consists of an index and a switching spring located on the circumference of the lower disk that acts on a series of four latches on the circumference of the top disk spanning from the aperture through to the numeral “3” on the date wheel. This switching spring can be moved outwardly in three positions, accounting for the four varying lengths of months, with its starting position, the innermost position representing 28 days. This is controlled by a cam with two depth profiles representing days with 30 or 31 days and a lever that pivots in three positions with its innermost position accounting for February, with 28 days, middle position for 29 days and outermost position for months with 30 as well as 31 days.

H. Moser & Cie. Endeavour Perpetual Calendar Tutorial; Endeavour Perpetual Calendar Funky Blue

In a month with 28 days, the control lever is in its innermost position and the switching spring assumes its initial position while in a month with 29 days, the control lever is in the middle position where it acts on the switching spring so that it assumes the first position. However, on months with 30 or 31 days, the lever is in its outermost position, and it is the two-step cam that will determine whether the switching spring occupies the second or third positions. Depending on the position of the spring, it acts on one of the latches, thus moving the upper date disk to the 1st of the following month. For instance, on a 28-day February, the spring, which is in its innermost position locks on the first latch, and the date disk shifts to display the 1st of March.

In addition, a pin on the top date disk indexes a ratchet wheel — their engagement akin to a Maltese cross system — which drives the central month wheel via an intermediate gear.

EXTREME REDUCTION: OCHS UND JUNIOR PERPETUAL CALENDAR

When Ludwig Oechslin founded Ochs und Junior in 2006, he began streamlining the complication even further by rethinking its basic design and in 2016, arrived at a perpetual calendar module that was made up of just nine components. The novelty lies not only in the way the calendar mechanism was constructed, but also the way the indications were displayed, which made the severe reduction possible.

The date is displayed using an outer ring of 31 perforations with an elongated colored date marker printed on a rotating disk beneath it. Thus, the marker appears through the perforation to indicate the date, which can be conveniently read against the 10-minute markers, each representing five days. The month, on the other hand, is indicated by a set of four perforations on a centrally mounted disk that makes a complete rotation in 12 months, while leap year is indicated by a colored dot that emerges on the outward facing perforation in February of a leap year. In other words, in February of three common years, the colored marker is on one of the three inward perforations.

Assembly of Ludwig Oechslin’s 12-part perpetual calendar mechanism

The mechanism is ingeniously simple. In fact, the best way to understand it is to forget all other ways a standard perpetual calendar accounts for leap years. A 12-hour wheel mounted on the hour pinion drives a 24-hour wheel which drives the date disk forward by four teeth every day. The date wheel has 124 teeth, hence four per day. During the three final days of the month, the date wheel starts advancing the month ratchet wheel, which drives the month disk via an intermediate wheel. The month disk carries a four-year Maltese cross wheel, which has four arms of equal length that are interspersed by four fingers, of which one is shorter than the rest. The arm beside this shorter finger has a colored dot to indicate leap year. As this four-year wheel rotates, the longer finger pushes against a small lever, causing it to protrude on three consecutive years that are not leap years, and on the fourth year, the shorter finger causes the lever to retreat, allowing the date disk to advance by a day to 29 February while the colored dot appears on the periphery to indicate leap year.

These examples are particularly enlightening in demonstrating that the ease of use and simplicity in design, construction and assembly of a modern perpetual calendar belie some seriously creative and complex solutions. As such, despite their obvious utility and necessity, these advancements remain a rarity in watchmaking.

Reference

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The post The Basics and Beyond: Perpetual Calendar appeared first on Revolution Watch.

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