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40: Precision

Antoine Martin: A Progressive Impulse

After a tumultuous few years, Martin Braun has introduced the world to the Calibre AM 39.001 the 324-component movement made entirely in-house by his new company. QP takes a closer look at the silicon-enhanced High Performance Escapement (HPE) and Aerodynamic Amplitude Stabilization (ADAS) system encased within the Antoine Martin QP01. Tim Treffry

The DLC-coated, stainless steel cased version of the Antoine Martin Perpetual Calendar. Day and month windows are at 10 and 2 o’clock with the large date display at 6. The leap year cycle at 12 and the am/ pm indicator at 9 make the calendar particularly easy to set.

The new brand, Antoine Martin, splices the names of its founders – a Swiss businessman, Antoine Meier, and the highly inventive German watchmaker, Martin Braun. Their first watch, manufactured entirely in their factory in Alpnach, near Lucerne, is a manually-wound, perpetual calendar available in a particularly striking black DLC-coated stainless steel version or gold in a choice of rose, yellow or white. The displays are unusually clear with a large date. The rear view highlights the large, slowbeating, balance and a power reserve indication. The movement has a number of extremely clever features, which will charm watch lovers who like to have special technical aspects to linger over; particularly where they improve performance. Martin Braun’s introduction to horology was in the 1980s in his father’s case-making workshop, CCM-Braun. In the days when the mechanical watch industry was in the doldrums CCM-Braun satisfied watch buffs’ hunger for something interesting, by salvaging high quality watch movements from earlier decades and re-casing them as, sometimes rather large, wristwatches. So perhaps Braun Snr and Jnr were responsible for starting the trend that was to follow as the industry revived.

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Reach for the stars After qualifying as a watchmaker, Braun started to develop a unique range with his name on the dial, announcing it to the world in the year 2000. He didn’t want to reinvent the wheel and used well-respected ETA base movements; his domain was between the movement and the dial. The model names were inspired by Greek mythology, his logo resembled the rising sun and he was interested in complications reproducing astronomical phenomena. His ‘Eos’ indicates the time of sunrise and sunset throughout the year, displaying it on large dial sectors for accuracy. Eleven versions, available to order, were made to best suit the latitude where the owner lived. Anther model shows the position of the earth in its orbit around the sun and ‘Selene’ has what is perhaps the most naturalistic portrayal of the phases of the moon ever achieved in a wristwatch. Needing further investment to develop his ideas, Braun joined the Franck Muller Group in 2007. Sadly, the timing of the move could not have been worse, running straight into a transitory recession in the watch industry. The Group had expanded too rapidly and an acrimonious breakup followed. Braun left the company, leaving his painstakingly created brand name, ‘Martin Braun’, behind him. After leaving the Franck Muller Group, Braun created his own movement production company MHO (Manufacture Horlogere Obwalden) in Alpnach, near Lucerne. And it is here that he developed his remarkable calibre AM39.001, which incorporates his 30 years of watchmaking experience and takes advantage of the extraordinary precision available in the manufacture of silicon escapement components. This provided a launch pad for the production of the new Antoine Martin range.

The rear view, here in the rose-gold version, highlights the 17.5mm titanium balance wheel with timing screws and precision beat adjuster. The red hand is the indicator for the 6-day power reserve. The unusual skeletonised three-armed balance cock maximises the view of the balance.

Building a bridge With his love of traditional watchmaking Braun has sought to build a bridge between the period, a century ago, when he feels that the most beautiful mechanical movements of the modern era were made, and contemporary production methods. He wanted to make a feature of the balance wheel and he wanted it to be big and slow. If one suggests that this flies in the face of the time keeping theory (which favours high frequency oscillators), Braun replies that large balances making the traditional 18,000 vibrations per hour (2.5hz) are "more beautiful"; a point that no lover of mechanical watches would argue with. Using titanium, a light but strong metal, enables the balance diameter to be increased to 17.5mm, which may be the largest ever in a wristwatch. The balance is free-sprung and its rate is regulated by recessed, gold, timing screws. A micrometre index permits unusually precise beat adjustment, but it is with the escapement of the new watch that Braun makes the leap from the traditional to the avant-garde. Although the traditional Swiss lever escapement is the most successful ever made, it involves compromises to accommodate the limited precision available in conventional technology. In the new Antoine Martin movement, use of a silicon escape-wheel and silicon lever with integral pallets enables the escapement geometry to be redesigned to create the ‘High Performance Escapement’ (HPE, see box). The main advantage of the new arrangement is that in the ‘stop, go’ world of the escapement, the work done by the escape-wheel in delivering impulse to the balance builds up gradually when the escapement is unlocked. As a result the energy transferred is increased by around 10 per cent. The low density of the silicon components, reducing their inertia, is another contributing factor. Moreover the silicon escapement does not require lubrication, thus increasing service intervals.

42: Precision

The ADAS way Braun accepts that watch lovers are promiscuous and will not wear the same watch day after day, so he wanted the Antoine Martin to have a long power reserve. With the efficiency of its escapement and gearing (see later) the new movement will run for six days. During this long running time the power delivered by the mainspring will inevitably decline causing the amplitude of the balance to drop. Classically, accommodating this problem would require a fusee or a remontoire; Braun decided to apply his knowledge of aerodynamics to provide a system called ‘Aerodynamic Amplitude Stabilisation’ (ADAS) to control the balance amplitude. The balance rim has four small lateral fins protruding from it producing eddies in the surrounding air as it swings. When the spring is fully wound and its power at a maximum, a spurred lever is placed close to the balance rim, interacting with these eddies to produce aerodynamic drag. As the spring unwinds, this lever moves further away and the drag is reduced, maintaining the balance amplitude as the impulse drops. Following the well-known principle that 'every little helps' Braun has further paid attention to the shape of the gear train teeth; a problem also addressed by Patek Philippe in recent years. In collaboration with Azurea SA, a Swiss precision-engineering company, Braun has produced a tooth shape, which increases torque transmission by 5 per cent. He has also modified the way in which power is delivered from the mainspring barrel to reduce fluctuations as the spring unwinds. The movement plates and bridges are given an attractive black finish – the precise details of which are known only to the company which produces it. Stainless steel bushes set in the plates provide the threads for the screws that attach the bridges. This is a watch on which a skilled watchmaker, perhaps in the German tradition, has lavished an almost bewildering attention to detail, but absolutely none of the effort is frivolous, it all contributes to producing a beautifully designed and long lasting product.

Further information:

This detailed view of part of the balance wheel shows the ‘Aerodynamic Amplitude Adjustment’ to accommodate the reduction in the power of the mainspring over the 6-day running period. Small lateral extensions on the balance wheel create eddies in the surrounding air as the balance swings. When the watch is fully wound, fins on the lever across the bottom of the picture are brought very close to the balance (but do not touch it) forming an aerodynamic brake. As the watch runs down the lever moves away and the effect diminishes stabilising the balance amplitude.

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Antoine Martin High Performance Escapement

In the traditional Swiss Lever Escapement (left), the impulse face of the lever pallet is flat. Impulse is initiated at full force after unlocking and continues steadily as the escape-wheel tooth moves across the pallet face pushing it away to impulse the balance.



In the Antoine Martin High Performance Escapement (right) the contact faces of the silicon lever and escape-wheel are slightly concave. This means that the impulse commences gently and builds up gradually as the momentum of the escape-wheel increases after unlocking. This design means that most of the impulse is delivered towards the end of the impulse phase and is made possible by the precision of silicon etching, which is much greater than can be achieved when machining conventional components. An added advantage is that the silicon escape-wheel is absolutely circular, allowing locking to be much shallower so that less energy is wasted when unlocking. Those with knowledge of escapements will realise that energy expended in the ‘run to banking’ is also reduced.