The “Exo” is derived from the Greek for external or outside and refers to the large balance wheel with screws, which is positioned outside of the tourbillon’s rotating cage. The idea of the Montblanc engineers when developing the innovative, patented Suspended ExoTourbillon was to create a one-minute tourbillon that would be more visible, further revealing its beauty.
The balance
This particular patented construction of the Suspended ExoTourbillon allowed the watchmakers at the Montblanc Manufacture in Villeret to have a large and impressive balance wheel and eliminate the need to increase the size of the movement or the case. The massive balance wheel is raised 3.2 mm higher than the dial and appears to be floating above it. This new suspended position has been made possible thanks to a new tourbillon bridge with only one stainless steel arm which is curved and mirrors the domed hour circle at 12 o’clock. It creates a three-dimensional look and a new fine watchmaking aesthetic.
Due to its asymmetric construction, the alignment of the ExoTourbillon bridge, with its solitary arm, represents a horological challenge and demands the utmost skill and dexterity to complete. The complexity of the patented ExoTourbillon comes from the dimensions of the long axis that need to be extremely precise, along with the complication construction itself, which requires that the balance’s axis must be perfectly perpendicular to the movement. A difference in positioning at the base of the bridge by just 5 microns (0.005 mm) can result in a deviation of 0.05 mm at the end of it, that is to say a gap multiplied by 10.
In terms of performance, this innovative, patented mechanical architecture of the ExoTourbillon saves more energy than a conventional tourbillon as the cage is smaller in size and free of the weight of the balance wheel. The weight of the tourbillon cage has been reduced, which means it weighs less than a conventional tourbillon. It is also balanced by two gold pillars to equilibrate the cage. The fact that the balance is positioned outside of the rotating cage also means that it isn’t affected by the inertia of the cage, therefore improving precision. Another key feature of the ExoTourbillon is the speed of its rotations. The cage completes one full rotation per minute thus able to also indicate the seconds, while also inviting users to admire the beauty of the tourbillon’s movement.
The large balance
The large balance wheel, beating at the traditional frequency of 18’000 oscillations per hour, has a diameter of 14.5 mm. This plays an important role in the performance of the timepiece thanks to its impressive 18 screws — two of which can be adjusted, and 16 of which are fixed — further improving precision and following the purest fine watchmaking tradition.
The case
Following pure horological tradition, the Manufacture movement calibre MB M16.68 is entirely decorated in the Montblanc Manufacture in Villeret with hand-crafted finishings such as Côtes de Genève stripes, inner angles, circular graining, beveling and a mirror-polished pawl with the hand-finished Minerva arrow. Inspired by the three-dimensional bridge construction, the round shape of the case, with its domed sapphire crystal on the front, has been built around the movement, contributing perfectly to the overall design. Entirely polished, the 44.8 mm case comes in 18K red gold and features a sapphire crystal on the case back which reveals the beauty of the hand-finished manually wound movement calibre MB M16.68. It also provides a totally transparent view of the Exo Tourbillon from the front to the back.
The dial
The sophisticated three-dimensional dial is constructed in eight different parts that have been decorated entirely by hand using traditional watchmaking techniques. The base is in 18K gold and has been highlighted with a hand-made guilloché pattern in places, and a sandblasted decoration in others, with polished steps framing the different finishing techniques. A refined guilloché pattern completes the aesthetic.
A silvery-white dome at 12 o’clock, with an azuré decoration in the centre, houses the hours and minutes counter, mirroring the three-dimensional effect of the outstanding Suspended Exo Tourbillon at six o’clock. Other details include 18K red gold hands to display the hours and minutes and a small second indication with a blue arrow on the Exo Tourbillon itself. In addition, a small plaque with the timepiece’s limited edition number has been applied to the dial that balances the Exo Tourbillon’s bridge construction.
A limited 58 pieces edition
This Montblanc Star Legacy Suspended Exo Tourbillon is limited to 58 pieces, paying tribute to the year the Montblanc Manufacture was founded in Villeret in 1858. The timepiece comes fitted with a black alligator leather strap supplied by the Montblanc Pelletteria in Florence, Italy and is equipped with a triple folding clasp with security pushers, offering a secure grip. To express reliability and performance, it is certified by the Montblanc Laboratory Test 500.
A limited Edition of 28 is also available with a case set with 54 baguette diamonds of 2.35 cts.
