Watch Insider: Montblanc Collection Villeret 1858 ExoTourbillon Rattrapante

Recently I had the opportunity to see the latest masterpiece from Montblanc’s Villeret collection, the 1858 ExoTourbillon Rattrapante, presented by new Montblanc CEO Jérôme Lambert. In this article, originally run on my blog, Watch, I explore the watch and provide original photos and a short HD video.

The Montblanc Collection Villeret 1858 ExoTourbillon Rattrapante was one of the most spectacularly complicated timepieces at the Hong Kong “Watches and Wonders” watch fair, where it made its debut. It was developed by the chronograph specialists at the former Minerva, now a part of Montblanc, and offers a challenging new take on the rattrapante, the most complicated type of chronograph to produce.

Unlike a conventional tourbillon, Montblanc’s ExoTourbillon frees the large screw balance from the burden of the rotating cage. Rather than offering a mere chronograph, the new model contains a split-second chronograph with two column wheels and a classical double clamp. And instead of an ordinary face, the watch’s dial is a fascinating, three-dimensional arena of massive gold and grand feu enamel. This masterful combination of the traditional watchmaker’s art and trailblazing innovations comes with an 18k white gold case and a regulator dial. The watch shows the time in a second time zone, includes a day/night indicator and is manufactured in a limited edition of 18 pieces. Ordinary chronographs define the upper limit of so-called “everyday” or “petit complications,” but split-second chronographs are “grand complications” in the truest sense of the phrase.

Montblanc Collection Villeret 1858 ExoTourbillon Rattrapante
Montblanc Collection Villeret 1858 ExoTourbillon Rattrapante


(Click here to view my interview with Jérôme Lambert, posted on

Extraordinary mechanical complexity, and almost 70 percent more components than in a conventional chronograph mechanism, are required to perform this watch’s most practical function, which is momentarily halting the split-second hand to indicate an intervening interval without interrupting the ongoing measurement of an elapsing interval by the chronograph’s elapsed-second hand. The watchmakers’ efforts are all the more laborious for delicate steel parts, which impose the utmost demands in manufacturing, finishing and assembly. The manufacturing of parts at Montblanc in Villeret is done almost entirely by hand, so substantial time and labor are required. All this is prior to the “mise en fonction,” the hours or even days of meticulous work that goes into the fine adjustment and, if necessary, delicate abrasion of the functional parts of the chronograph and split-second mechanism. The “mise en fonction” is performed on the fully assembled mechanism: each function is triggered and then scrutinized under a loupe; after noting even the slightest irregularities, the watchmaker disassembles the mechanism and finely tunes it, which involves filing away a mere 1/100th of a millimeter or making a miniscule shift in the position of a lever; the movement is then reassembled and re-examined under magnification. This process may need to be repeated five, six or more times until everything functions perfectly.


When the wearer triggers the chronograph’s functions, he can see through the sapphire crystal caseback the column-wheel (which controls the basic chronograph functions), the split-second column-wheel (which opens and closes the brake-clamps of the split-second wheel), and the manually bevelled steel levers (which, when the corresponding buttons are pressed, transfer their commands to the column wheels and to the gear-coupling, the zero-return hearts and the brake-clamps). Also visible are the slender, elegantly curved, steel springs that press the rattrapante-clamps against the split-second wheel when the rattrapante button at 2 o’clock is pressed, allowing the user to read the duration of an intervening interval. When this button is pressed again, the clamps spread apart and the zero-return heart automatically returns the split-second wheel to synchrony with the chronograph wheel so that the split-second hand rejoins the chronograph’s elapsed-seconds hand and resumes running in unison with it.

Montblanc has also created a distinctively ingenious tourbillon mechanism for the watch. The Ancient Greek prefix “exo” means “outside,” and it is applicable in two senses for the ExoTourbillon. First, the rotating cage and the escapement are positioned outside the movement’s plate and are located more or less alongside the movement. Second, the balance is installed outside the rotating cage and oscillates on a different plane. This repositioning has been used in other timepieces in the Montblanc Collection Villeret 1858. The uncommonly large and heavy balance would have required a larger rotating cage if it had been mounted inside a conventional tourbillon construction. But the ExoTourbillon cage has a smaller diameter than the balance and rotates beneath the gleaming golden screw balance. The balance is borne between two bridges, the upper of which has a looped shape that recalls a horizontal figure-eight, or infinity symbol. The tourbillon rotates in a two-point bearing at the foot of the axis.


Another exclusive feature of the ExoTourbillon is the speed of its rotations, each of which requires four minutes. Conventional tourbillons typically complete one rotation per minute. Slowing the speed of the rotations makes it more visually appealing, and requires less energy from the barrel, but produces the same compensating effect as a faster tourbillon. The hairspring, with an upward Phillips curve at its outer end, oscillates at the traditional frequency of 18,000 vph (2.5 hertz), enabling the chronograph to measure elapsed intervals to the nearest 1/5 second. Reducing the tourbillon’s rotational speed by 75 percent yields considerable energy savings. The rotating cage is smaller and has less mass, so its rotational motion requires less energy as well. Furthermore, the balance is freed from the weight of the rotating cage, which yields a further reduction in its energy requirements. Montblanc’s device requires more than 30 percent less energy than conventional constructions, and this is advantageous for the functioning of the split-second chronograph. Also beneficial is the separation of the balance from the rotating cage: the accuracy of the balance’s amplitude is improved because the balance is not influenced by the inertia of the cage.

Due to the ExoTourbillon’s innovative configuration, and despite the greater mechanical complexity of the split-second chronograph, the rattrapante can function more precisely. It can also rely on the same barrel and the same power reserve as the base chronograph movement. This would not have been possible in a chronograph without the patented ExoTourbillon construction, which also includes a patented energy-saving mechanism.

Here is the short video of the The Montblanc Collection Villeret 1858 ExoTourbillon Rattrapante that I shot in Zurich. Specs for the watch and its movement, including the price (in euros), are below.



Manufacture Calibre 16.61

Type of movement: Hand-wound movement with split-second chronograph, small seconds, second time zone with 24-hour display and separate four-minute tourbillon

Chronograph: Split-second chronograph mechanism with two column-wheels, rattrapante-clamps with springs at both sides and horizontal coupling with sliding gear

Dimensions: Diameter = 38.4 mm; height = 11.9 mm

No. of components: 411

Power reserve: 55 hours

Balance: Screw balance; diameter = 14.5 mm; 59 mgcm2

Frequency: 18,000 vph (2.5 hertz)

Tourbillon: One rotation every four minutes

Hairspring: With Phillips terminal curve

Plate: Rhodium-plated nickel silver with circular graining on both sides, hand-chamfered edges

Bridges: Rhodium-plated nickel silver with côtes de Genève (Geneva waves), recesses circular-grained on both sides, hand-chamfered edges

Gear-train wheels: gold-plated, circular-grained, chamfered, diamond hubs on both sides

Pinions: polished faces and toothing, burnished pivots

Displays (watch): Hours in the first and second time zones at 6 o’clock, minutes from the center, small seconds at 9 o’clock, day/night indication with 24-hour display at 4:30

Displays: Chronograph’s elapsed-seconds and split-second hand from the center, counter for thirty elapsed minutes at 3 o’clock

Case: Limited edition of 18 watches with 18k white gold cases; domed sapphire crystal, screwed caseback with sapphire viewing window

Dimensions of case: Diameter = 47 mm; height = 17.5 mm

Water resistance: 30 meters

Crown: With integrated chronograph button

Push-pieces: At 2 o’clock for the rattrapante function and at 8 o’clock to reset the time in a second zone

Dial: 18k gold with grainé décor, applied scales in grand feu enamel on gold for the running seconds, the hours, the 24-hour display and up to 30 elapsed minutes

Hands: Blued steel, chronograph hand made of Pfinodal

Strap: Hand-sewn alligator-leather strap, pronged buckle in 18k white gold

Price: 250,000 euros



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