First launched in 2008, Horological Machine No2 revolutionized the world of haute horlogerie with its distinctive rectangular shape, flying buttresses, dual portholes and modular construction. The crystal-clear sapphire case of HM2-SV then took the revolution even further by offering unprecedented visual access into the meticulously hand-finished, 349-component engine powering the indications on HM2’s iconic twin dials.
But all good things come to an end and, after three very successful years, Horological Machine No2 takes one last bow on center stage with two final limited editions of 18 pieces each, both featuring sapphire cases: HM2-Black SV and HM2-Red SV close the HM2 collection, thus ensuring its exclusivity.
Synthetic sapphire watchcases are extremely rare for good reason. While sapphire retains its strength at high temperatures, has zero porosity and (below 300°C) does not react to acids, the very properties that make it so attractive also make it extremely difficult to mill, requiring sophisticated (and expensive) diamond tools to machine, followed by careful polishing to turn the opaque freshly cut or drilled surface transparent. The complex, three-dimensional form required for HM2-SV’s case, with its bevels, mounting holes, porthole cut-outs and embedded gasket track, pushed the limits of sapphire technology beyond what was thought possible. No less than 55 hours of milling, drilling and polishing are required just to create each sapphire case.
While both new final models are derived from the original HM2-SV, each has its own very distinctive identity.
HM2-Black SV features a sapphire case, black dials and a black PVD titanium baseplate that makes a strongly contrasting backdrop for the unique architecture of the HM2 Engine inside, which is framed by an electric green rubber gasket clearly visible through the transparent top. Turning the watch over reveals yet another splash of colour from the vivid green 22K gold winding rotor.
HM2-Red SV has its sapphire case black dials mounted on a regal red gold baseplate. The black dials, black rubber gasket and the rich red of the caseback provide a stunning juxtaposition with HM2’s silver Engine. Turning the watch over rewards the viewer with the sight of MB&F’s signature 22K red gold battle-axe rotor complimenting the red gold of the caseback.
The HM2 engine, developed by award-winning master watchmaker Jean-Marc Wiederrecht, features the world’s first mechanical movement offering: Instantaneous Jump Hour, Concentric Retrograde Minutes, Retrograde Date, Bi-Hemisphere Moon Phase and Automatic Winding. One highlight (of many) of the HM2 complication is the highly energy-efficient Jump Hour/Retrograde mechanism developed by Jean-Marc Wiederrecht, which uses his exclusive (and patented) asymmetrical-tooth gear wheels to ensure high precision and play-free functionality.
The sapphire case: Surprisingly, because it is largely unseen, the sapphire cases of these final editions are a substantial 3.6mm thick. Thanks to anti-reflective treatment on both sides – in itself no small technological feat to uniformly apply – the case becomes virtually invisible and allows for full appreciation of the myriad nuances of the complex movement. Eight mounting bolts traverse the sapphire plate like pillars, passing through the twin tracks of the rubber gasket sealing the sapphire case and caseback, add to the architectural nature of the three-dimensional case.
The case, with its flying buttresses, bolted portholes, was so complex – over 100 components go into its construction alone – that it could only be developed with an innovative modular method inspired by the Meccano sets of Maximilian Büsser’s childhood. And in line with best engineering principles, this modularity also simplifies future refurbishment of the case should it ever be necessary.
Technical Innovations: The principle technical challenge in developing the movement was ensuring that the jumping hour functioned both instantaneously and simultaneously when the retrograde minute flies back from 60 to 0. And not only instantaneously: without using excessive energy. The usual method of activating Jumping Hour indications is to store energy in the minutes before the change to power the jump; however, while this energy is being accumulated it takes power from the balance causing it to loose amplitude – an effect detrimental to time-keeping precision. Wiederrecht’s solution was as brilliant as it was simple: he designed a ingenious mechanism so that when the minutes fly back, a snail on the minute mechanism hits the hour star causing the hour to jump. The hour jumps instantaneously with the minutes because it is triggered by the minutes and, as the jump is powered by the energy of the minutes flying back, it has virtually no effect on the amplitude of the balance.
While the complications and functionality operate with maximum efficiency, with 349 components in the movement alone, there are no doubting HM2’s credentials as an incredibly technical tour de force.
The complication has another very special feature. Specific gears in HM2’s movement are manufactured to extremely high precision using Mimotec’s UV-LIGA technology. These gears mesh together with a virtually a no-tolerance/no-play engagement. Normally, gears interacting this tightly would bind; however, Wiederrecht’s patented asymmetrical-split-tooth gear design ensures this does not occur. The high precision of this gearing enables very accurate time-setting and offers high reliability.
To maximise the efficiency of MB&F’s already iconic battle-axe automatic rotor, one of the 22K gold blades was machined down to a razor sharp edge of just 0.2mm – a dimension that pushed the very limits of micro-machining!
While Horological Machine No2 is a high-tech machine of the 21st century, the quality and hand execution of the fine finishing is a showcase of the very best in traditional craftsmanship. Light flashing off hand finished mirror-polished surfaces and immaculate bevelling brings vivacity to the rich combination of colours, materials, shapes and textures.
Movement – Jean-Marc Wiederrecht/Agenhor designed functionality regulated and powered by a Girard-Perregaux base. Balance oscillating at 28,800 bph. 22K red gold battle-axe automatic winding rotor (green PVD coated 22K for HM2-Black SV). Number of components – 349 including 44 jewels.
Functions – Left dial: Retrograde Date and Bi-Hemisphere Moon Phase. Right Dial: Jumping Hours and Concentric Retrograde Minutes.
Case – HM2-Black SV: Sapphire/black PVD coated titanium baseplate, electric green gasket, limited to 18 pieces. HM2-Red SV – Sapphire/18K red gold baseplate, black gasket, limited to 18 pieces. Dimensions (exclusive of crown and lugs) – 59 mm x 38 mm x 13 mm. Water resistant to 30 meters (3 ATM). Number of parts – 120 (case only).
Sapphire crystals – Sapphire case top and crystals over the dual dials treated with anti-reflective treatment on both faces. Display back with anti-reflective treatment on single face.
Dials – Brushed sapphire and black metallic disks.
Strap & Buckle – Black hand-stitched alligator with 18K gold & titanium folding buckle.
Presentation box – Precision engineered aluminium and leather instrument case featuring an integrated Rüeger thermometer.