First unveiled in 2018, the N ° 9 Horological Machine - nicknamed the HM9 “Flow” - pays homage to the extraordinary automotive and aeronautical design of the 40s and 50s. The result? An unprecedented case that evokes the fluid and aerodynamic lines of the time. Despite its striking exterior, MB&F founder Maximilian Büsser described the internal movement of the HM9 as "the most beautiful movement ever created so far". The next step was of course to enclose the HM9 movement in a transparent sapphire crystal case.

A curved, domed, precision-fitted three-part sapphire crystal and precious metal outer shell is sealed with a proven combination based on a patented three-dimensional gasket and high-tech bonding process. Two fully independent cantilevered rockers funnel data into a differential that turns two beats into a single coherent time pulse. The ultra-precise bevel gears effectively drive the movement energy and stream of information through a 90 ° angle to provide timekeeping on a sapphire crystal dial, marked with Super-LumiNova.

On the reverse, under each balance wheel there are coaxial propellers: twin turbines that rotate freely as an element of pure visual interest, waiting for the start of a new type of exploration. Two years after the first editions of the HM9 Flow "Air" and "Road" conquered earth and sky, the HM9-SV takes us into the ocean depths - the last kingdom on Earth that still holds countless secrets to unravel . Ahead of us is an exploration ship from Atlantis, powered by divergent technology, which appears both familiar and alien to our eyes.

On the outside, the lines of the HM9-SV follow the model of its predecessors called "Road" and "Air". The laws of fluid dynamics remain dominant in its design, although the centrality of hydrodynamics allows the HM9-SV to adopt a softer style than the internal sharp angles and parabolic curves of previous Flow versions. From a technical point of view, the reworking of the dimensions was necessary to justify the differences in the material properties of the sapphire crystal which, although it is extremely hard, risks breaking abruptly under pressure, while a metal can at most deform. The softer lines of the HM9-SV minimize potential areas of mechanical vulnerability, while reinforcing the aesthetics of the ocean inhabitants.

The movement of the HM9 follows in the footsteps of the movements of Horological Machines N ° 4 and N ° 6, putting aside the conventions related to the construction of the movement. Its three-dimensional assembly of gears, gears, plates and bridges takes on unexpected shapes that animate the dynamic outer case, creating a pulsating union of mechanical entrails and endoskeleton in a crystalline body. The traditional 2,5 Hz (18.000 a / h) balance wheel frequency may seem curiously anachronistic in a modern watch, but the shock sensitivity associated with a lower beat rate is compensated for by having two balance wheels instead of one. From a statistical point of view, two identically calibrated systems offer a better average reading than a stand-alone system, which could provide anomalous results for countless reasons.

To further reduce shock sensitivity, the HM9-SV editions feature a new shock absorption system: coil springs positioned between the movement and the case. The springs are laser made from a solid, polished stainless steel tube, which offers excellent elasticity and limited lateral displacement. A planetary differential, the movement gear, has the task of averaging the time scan transmitted by the twin balance wheels of the HM9 movement, which then provides a final reading to be displayed on the perpendicularly oriented dial. This complex mechanical calculation was partly revealed in the original HM9 Flow, with sapphire crystal domes set on each balance wheel and with a magnifying panel mounted above the planetary differential, to visually underline the importance of its chronometric role. In HM9-SV, every aspect of the movement invites discovery; the eye can follow the interaction of the components, from the barrel to the balance wheel, from the differential to the dial.

In order to seal the external sapphire crystal components in a single watertight case, new solutions had to be thought of. A patented three-dimensional rubber gasket was already used in the original HM9 Flow to ensure water resistance when the tripartite case was assembled together. In the HM9-SV the 3-D gasket remains, but the sapphire glasses are fused with the metal frame thanks to a high-tech bonding process, based on an excellent in-house developed method that takes advantage of vacuum and high temperatures. The result is a water pressure resistant seal of 3 ATM (30 m), despite the virtually invisible seams between the sapphire components and the minimalist 18K gold frame. The HM9 Sapphire Vision is available in four editions, each limited to just five pieces: two editions with an 18K red gold frame, paired with a movement coated in black NAC or blue PVD; and two editions with 18-karat white gold casing, featuring a purple PVD-coated or red gold-plated movement.

Corundum, commonly known in its gem form as sapphire glass, is one of the hardest minerals known to man. Its hardness is only surpassed by a few other materials, in particular diamond (crystalline carbon), which has a score of 10 on the Mohs hardness scale, while corundum has a score of 9. This exceptional hardness means that the The sapphire crystals of the watches are virtually scratch-resistant and offer unbeatable long-term material integrity and legibility, as well as imparting a level of prestige not associated with standard silicate glass or clear polycarbonate, the two most common alternatives to sapphire crystal glass. watches.

In parallel, this also means that sapphire is extremely challenging to machine in complex three-dimensional shapes, a challenge made even more difficult by the tight machining tolerances required in watchmaking. From its first creations to today, MB&F has worked with increasingly complex sapphire glass components: The HM2 "Sapphire Vision", the double-curved glass of the HM4 "Thunderbolt", the recent HM3 FrogX and the hallucinatory body of the HM6 “Alien Nation” are perfect examples of this. The preparation of the glasses for a single case of HM9-SV requires about 350 hours of careful processing and polishing; weeks of work that would extend considerably were it not for the 16 years of experience that MB&F has accumulated in overcoming the limits of sapphire crystal design from 2005 to today.

The result of three years of development, the movement of the HM9 was conceived and assembled entirely in-house, thanks to the experience accumulated so far with the 18 different MB&F movements. Longtime members of the MB&F Tribe will recognize the mechanical pedigree of the HM9 movement. Its dual balance wheel system with differential derives from the similar mechanism used in the Legacy Machine N ° 2, albeit in a distinctly different aesthetic form. While the LM2 emphasized the purity of design and hallucinatory effect of its suspended oscillators, the HM9 is elated in its celebration of expressive design. Two balance wheels striking within the same movement inevitably elicit a resonance effect, the mechanical phenomenon that describes oscillators connected in a state of harmonic mutual excitation. As with the LM2 movement, the Horological Machine N ° 9 deliberately avoids inducing the resonance effect. The goal of including two balance wheels is to obtain discrete sets of chronometric data that can be translated from a differential to produce a stable average reading. This goal would not be achievable with two balance wheels that oscillate perfectly in phase, offering the same chronometric data at all times.

Adjusting the twin rocker arms is a challenge in itself. Industry standard equipment used to adjust a balance wheel assembly uses the sound emitted by an oscillating balance wheel to measure the frequency of the beats. Since the movement of the HM9 has two sets of rockers operating simultaneously, creating two sets of sounds, this method does not work in this case. Each example of the Horological Machine N ° 9, first launched in 2018, had to be adjusted by first locking one balance wheel to adjust the other and vice versa. Once both rockers were operated, the calibration shifted slightly, making it necessary to lock and re-adjust the rockers several times before obtaining an optimal chronometric result.

Since then, the MB&F team has made significant progress in timing adjustment techniques, largely thanks to the experience gained during the creation of the Legacy Machine Thunderdome. The HM9-SV has thus benefited from a few more years in terms of specialist experience in this field: it is not much in terms of time, but it is immeasurable in terms of savoir-faire. 

Price about 440.000 EURO.