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475 components revealed in a streamlined, sapphire crystal case

Horological Machine No6 SV (SV for “Sapphire Vision”) adds an extra three-dimensional layer to the biomorphic beauty of the HM6 ‘Space Pirate’ by revealing the mechanical marvels of the unique Engine within. The complex curves of two transparent sapphire crystal plates sandwich a precious metal "streamliner" case band, creating two horological amphitheatres dedicated to the appreciation of exquisite, hand-finished micro engineering.

"I always thought that the most beautiful part of HM6 was its movement, and that it was a shame not to show it. But it was only recently that the technology of machining sapphire crystal allowed us to create such a complex case,"explains MB&F founder Maximilian Büsser.

The metal case band is distinguished by horizontal lines reminiscent of the American Greyhound “Streamliner” buses of the 1950s and '60s, which grew out of a late Art Deco style known as Streamline Moderne. The sandwich construction is punctuated and highlighted by the vividly coloured stripes of the water-resistance seals.

At the front, two spherical domes rotate vertically, respectively displaying hours and minutes in large, highly legible numerals. Aft, twin spherical turbines spin horizontally, driven by the rotor and multiplying gearing that automatically regulates the winding system to minimize stress and wear.

A central dome houses a 60-second flying tourbillon, the precision regulator of the HM6 Engine. However, high-precision regulators are especially sensitive to changes in oil viscosity, and ultra violet radiation gradually breaks down lubricating oils. This is why HM6 features a retractable, semi-spherical, titanium protective shield; when closed, it blocks harmful radiation from prematurely oxidising the lubrication oils in the regulator. A crown at 9 o'clock opens and closes the cover in –and like–the blink of an eye.

The nine sapphire crystal domes – five on top and four underneath – are carefully fastened to the transparent plates thanks to a special gluing process, achieved under vacuum in a high temperature oven. This offers maximal strength and water resistance.

As entrancing as its organically curved exterior case is, the real star of HM6 SV is its Engine, which doesn't simply take centre stage but the whole auditorium. The 475 finely-finished components make up the highly complex movement, the result of more than three years’ worth of development.

Horological Machine No.6 ‘SV’ is a limited edition of 10 pieces in platinum/sapphire crystal and 10 pieces in red gold/sapphire crystal.

There will only be 100 HM6 movements made in total.

Design:The inspiration for HM6 SV’s precious metal case band comes from the late Art Deco style known as Streamline Moderne, one manifestation of which was the distinctive horizontal lines running along the iconic Greyhound Streamliner buses of the 1950s and '60s.

Streamlining was a concept first conceived by industrial designers who stripped the ornamental aspects of Art Deco design to focus on the scientifically pure aerodynamic concept of motion and speed.

Next to the streamlined case band, the organic curves of HM6's case derive from an early 20th century art movement labelled "biomorphism", in which art is modelled on the naturally occurring shapes and forms found in nature and living creatures.Biomorphic expressions can be found in art like Henri Matisse's eminent work, Le bonheur de vivre(The Joy of Life); in architecture as exemplified by La Sagrada Familia, the famous cathedral in Barcelona by Antoni Gaudí; and many works by contemporary designers including Marc Newson. But few have been as influential or as passionate about biodynamic forms as German industrial designer Luigi Colani, whose body of work spanned cars, furniture, electronics, a grand piano, and even a ballpoint pen.

Engine: The Engine of HM6 SV required more than three years of development due to the demanding challenges that had to be overcome. The aluminium indication spheres displaying hours and minutes are machined from solid blocks of metal to an ultra-light paper thickness and revolve on ruby bearings. The spheres rotate vertically at 90° to the plane of the movement, which is extremely rare in a wristwatch due to the complexity of the drive train and gearing required.

The eye-catching central tourbillon perched high above the movement is a flying tourbillon developed by MB&F specifically for HM6. The choice of such a sophisticated regulator was necessitated by the restricted space under the top of the sapphire crystal dome, which could not accommodate the upper supporting bridge of a standard balance wheel.

The flying tourbillon can be protected from ultraviolet radiation, which speeds up the oxidation of lubricating oils in the escapement and movement, by a retractable semi-spherical shield enveloping the tourbillon with four overlapping, curved blades. The shield is operated by a crown on the left side of the case. These blades are paper-thin and had to be machined from a solid ingot of titanium.

The two spherical turbines, each composed of no fewer than 15 curved vanes, are machined in two hemispheres from solid blocks of aluminium. These turbines are driven from the rotation of the automatic winding rotor by a gear train designed to amplify the number of rotations. As (air) friction increases exponentially (squared) as a function of velocity, if the winding rotor starts rotating too quickly – most likely due to highly active movement of the wrist air friction on the turbines increases and helps counteract the excessive speed to minimise wear.

As may be expected with such sui generis movement architecture, nearly every component and mechanism had to be developed from scratch specifically for Horological Machine No.6. The result speaks for itself.

Case:The case of HM6 SV is a sandwich construction of a precious metal case band between two transparent sapphire crystal plates. The case band, in either 950 platinum or 5N+ red gold, forms a protective wall around the movement and supports the articulated lugs. Horizontal lines traversing the perimeter of the case band visually break the height of the case and accentuate the movement within.

The sapphire crystal plates on the top and bottom were particularly difficult to machine and polish due to their size and the complexity of the curves. The domes capping the indications (top and bottom), turbines (top and bottom), and flying tourbillon were then meticulously fastened to the transparent plates thanks to a special gluing process, achieved under vacuum in a high temperature oven. This offers maximal strength and water resistance.

Sapphire crystals everywhere:The production of HM6 SV's 11 sapphire crystals, including two large case plates (top and bottom) and nine domes – on top and bottom of the two time indications and two turbines, plus one over the flying tourbillon – posed quite a challenge. Each was first machined from a solid block of sapphire crystal, which is the second-hardest, naturally-occurring mineral on earth after diamond. It is an incredibly demanding material to shape into complex forms.

Aftermachining each block of sapphire crystal inside and out with diamond-tipped tools, the shapes have to be highly polished, both inside and out, to make them transparent. The domes are especially ambitious, as the walls have to be of absolutely uniform thickness; otherwisethe slightest inconsistency creates disconcerting optical distortions.

Technical specifications



Three-dimensional horological engine developed exclusively for HM6 by MB&F with David CandauxHorlogerie Créative

Flying tourbillon with retractable semi-spherical titaniumshield

Iridescent blue platinum 950 battle-axe automatic winding rotor

Twin aluminium turbines driven by winding rotor

Power reserve: 72 hours

Balance frequency: 2.5 Hz / 18,000 bph

Number of components: 475

Number of jewels: 68


Hours and minutes on separate semi-spherical aluminium indications

Left crown opens/closes tourbillon shield; right crown for time setting and winding

Dual turbines regulate the automatic winding rotor


Sandwich construction of two transparent sapphire crystal plates on either side of a central precious metal case band

Materials: 5N+ red gold/sapphire crystal or 950 platinum/sapphire crystal

Dimensions: 51mm x 50mm x 22.7mm

Number of components: 78

Water resistance: 30m / 3atm

Strap & Buckle:

Hand-stitched alligator strap with custom designed folding buckle matching the case band.

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