Watches & Wonders: Making the ExoTourbillon Rattrapante

Releasing the ExoTourbillon Rattrapante at Watches and Wonders in Hong Kong was a big public relations coup for Montblanc. The newest addition to the Collection Villeret 1858 is a rarity when most of the other exhibitors made material or colour scheme changes whereas Montblanc introduced an uniquely constructed and innovative tourbillon.

Montblanc Collection Villeret 1858 ExoTourbillon Rattrapante.

Montblanc Collection Villeret 1858 ExoTourbillon Rattrapante

In the ExoTourbillon, Montblanc has positioned the rotating cage and escapement outside of the movement plates, along the movement rather than within. Next, the balance itself has been installed outside the carriage and oscillates on a different plane. With this “emancipated” construction, the Collection Villeret 1858 ‘Exo’ or ‘Outside running’ Tourbillon Rattrapante benefits from size and energy savings when compared to regular tourbillon complications- importantly, the larger rotating cage is no longer required and the ExoTourbillon cage has a smaller diameter than the balance, rotating beneath a gleaming golden screw balance.

Completing a rotation in four minutes rather than one rotation per minute as in a conventional tourbillon, the slower pace allows for both aesthetically pleasing viewing and technically innovative energy savings without reduction of the gravity-compensating effects of a faster tourbillon.

Upwards of 30% energy savings over a traditional tourbillon by way of the smaller rotating cage and a balance free of the spinning carriage means more power to the rattrapante chronograph complication. [more on the Tourbillon aspects at Cosmone.com]

The stop-start clamps of the rattrapante mechanism on the ExoTourbillon Rattrapante.

Mise En Fonction: The building of Montblanc’s Rattrapante Chronograph

Operation of a rattrapante chronograph is surprisingly uncomplicated where history of its invention is quite as clear cut. It’s quite likely that the first split-second chronograph was built by the Swiss watchmaker Louis-Frédéric Perrelet, the grandson of the watchmaker Abraham-Louis Perrelet of Neuchâtel, who invented automatic winding by means of an oscillating weight in the 1770s. Louis-Frédéric Perrelet presented his “time counter with double counter” in 1827. This invention included two second-hands positioned one above the other: one of them ran continually whenever the chronograph function was active; the other could be momentarily halted at the push of a button to measure an intervening interval. When this button was pressed again, the temporarily halted hand would catch up and return to synchrony with its companion. The French verb rattraper means “to catch up”, so Perrelet named his ingenious mechanism “rattrapante”.

Other sources credit the invention of the split-second chronograph to the Austrian watchmaker Joseph Thaddäus Winnerl, who settled in Paris in 1829. Winnerl, in contrast to Perrelet, devised a construction with a heart-disc and a heart-lever that exerts pressure to return the rattrapante-hand to the desired position. The system with a heart-disc, which is still in use today, inspired the two Swiss watchmakers Henri-Féréol Piguet and Adolphe Nicole to create a zero-return mechanism for chronographs around 1862.

Mise En Fonction

Rattrapante or split-seconds chronograph are by their very nature two chronograph mechanisms in one with a handful of shared components yet in terms of mechanical complexity equipped with almost 70% more components than a conventional chronograph. Now, consider that you’re going to put that into a movement just 11.9mm thick. In short, meticulous hand crafting, finishing and assembly.

Once the mechanism has been fully assembled, the traditional art of mise en fonction is performed where the chronograph function is triggered and then the interactions of the column-wheels (two), gear-coupling, zero-return hearts, brake clamps, etc are monitored under a loupe. At the slightest irregularity, the watchmaker dissembles the mechanism and tunes it once more- usually filling a smaller than hair’s width from a gear or making an almost imperceptible shift of a lever. The movement is then put back together and then examined under magnification once more during operation. The process is repeated till everything runs perfectly (usually six or more times).

The grand theatre of haute horlogerie

The classical aesthetics of the ExoTourbillon Rattrapante betrays the immense functionality and wealth of information available at the owner’s finger tips. First, a breakdown of the watch face:

At 6 o’clock– hours in the first and second time zones.
From the centre– minutes, chronograph elapsed seconds and rattrapante seconds.
At 9 o’clock– small seconds.
At 4:30 –  24 hour day and night indicator.
At 3 o’clock – counter for thirty elapsed minutes.

Next, the ‘grand theatre’- the dial of the Collection Villeret ExoTourbillon exists on multiple levels. The ExoTourbillon is positioned outside the movement plate within a partial openworked recessed dial. The regulator dial is a multipart construction of white gold with its surface plated with rhodium and decorated with graine decor. The scales on the registers are crafted as grand feu enamel appliques. As you might be aware, grand feu is amongst the oldest and most technically challenging techniques for decorating timepieces, the benefit of this tradition imbues the dial with colour and gleam for centuries. This model is available in 18 karat white gold case and is strictly limited to 18 pieces only.

Mise En Fonction

The stop-start clamps of the rattrapante mechanism on the ExoTourbillon Rattrapante.

Montblanc Collection Villeret 1858 ExoTourbillon Rattrapante.

Mise En Fonction

Mise En Fonction