Born from an approach that is unique in the world of modern watchmaking, the new Chronomètre FERDINAND BERTHOUD FB 1.3 is the most exclusive to date, coming on the heels of the FB 1.1 chronometer that won the “Aiguille d’or” Grand Prix award at the 2016 Grand Prix d’Horlogerie de Genève.
The Chronomètre FERDINAND BERTHOUD FB 1.3 picks up all the aesthetic and technical features of the previous versions that were respectively crafted in 18-carat white gold (FB 1.1) and 18-carat rose gold (FB 1.2). The 44 mm-diameter case of this watch sits naturally and comfortably on the wrist. Composed of a 950 platinum cylinder housing the movement, it comprises two octagonal-shaped side pieces in polished platinum that contribute to its distinctive shape. The latter is inspired by an overhead view of a marine chronometer fitted inside its case: its round shape is cut through by the arms of the gimbal suspension that holds it in place when the ship is at sea. The grey ceramic lugs are secured to the case middle by two stylised titanium bolts marking the starting points of the hand-stitched double-sided alligator leather strap. The same ceramic is also present on the medallion adorning the knurled platinum crown. Finally, four ‘portholes’ cut out from the sides of the case provide a chance to admire the fusee-and-chain mechanism in action, as well as to allow light to flood through the movement.
Another opening in the satin-brushed nickel silver dial reveals the wheel driving the tourbillon carriage and the seconds wheel to which the central seconds hand is fitted, an unusual feature on a tourbillon. This slim black hand sweeps around a translucent sapphire railtrack circle around the rim of the dial. The hours and minutes are offset at 12 o’clock on a black lacquered subdial bearing white Arabic numerals and white gold cut-out hands. The same black shade also graces the chamfered edges of the dial openings. The nature and origin of the Chronomètre FB 1.3 are also indicated on this large dial that is engraved with the inscription “Chronomètre Val-de-Travers Suisse”. Far more than merely representing a signature or an appellation of origin, it proudly proclaims the model’s identity.
The way the FB-T.FC calibre is built is a truly unique phenomenon on the contemporary watchmaking scene. This hand-wound movement features 15 bridges and three half-bridges in nickel silver, framed by polished titanium pillars surrounding the mechanical organs. This construction is typical of 18th century marine chronometers, and enables the portholes of the Chronomètre FERDINAND BERTHOUD FB 1.3 to reveal the interior of the watch. Equally high aesthetic standards apply to the design of all components, and especially to the symmetrical visual balance characterising the various sets of components.
This movement is one of the rare examples to feature a fusee-and-chain transmission, which is the oldest historical solution developed to ensure constant force for the escapement. This system acts like an automatic gear box, with the torque delivered by the barrel varying according to the level of winding.
When the movement is fully wound (53 hours of power reserve), the chain is entirely coiled around the small end of the fusee and the barrel spring is at maximum power. This force dwindles in the course of time, as the chain coils around the drum, moving from the small to the large end of the spindle-shaped fusee. The variation in the diameter of the fusee compensates for the reduction of the mainspring torque. The escapement thus receives constant energy, thereby equalling out the amplitude of the balance wheel and thereby enhancing the movement’s timekeeping precision.
The quest for slenderness
The distinctive nature of the FB-T.FC lies in the fact that its barrel and fusee are reversed, upside down, and above all suspended – meaning they are held on one side only. This helps save a few precious millimetres and contributes to the overall slimness of the calibre. At just 7.96 mm thick, the movement powering the Chronomètre FERDINAND BERTHOUD FB 1.3. is the thinnest in its category and a patent has been duly filed for this construction.
Safeguarding the movement
When the mainspring is associated with a fusee, the barrel drum turns in one direction while the spring is unwinding, and in the other during winding, thus serving to coil the chain. During the winding of this type of mechanism, the movement generally stops running. To counteract this effect, the FB-T.FC is equipped with a distinctively designed differential gear, enabling the balance-wheel to continue oscillating even during winding and thus preserving the movement’s precision timekeeping properties. Another patent has also been filed for this device.
The winding mechanism fitted with a pinion featuring cone-shaped toothing, together with a large-diameter knurled crown, enables smooth winding of the movement – a gentle motion that naturally enhances the quality of the rapport established between the watch and its owner, which plays an essential role in the case of a hand-wound watch.
As typically found on fusee-and-chain mechanisms, the barrel of Calibre FB-T.FC is equipped with a “Maltese Cross” stopwork device. The latter serves to limit the number of winding turns of the mainspring to around six, and to use only the most stable portion of this spring – thereby breaking free of its far ends. This device also servers as a buffer when the barrel is fully wound. At that point, the mainspring torque exerts a 3 kg force, which is considerable for components measuring just a few millimetres.
To perfect the security of the movement, the engineers at Chronométrie FERDINAND BERTHOUD have endowed the crown with a dynamometric function serving to avoid any damage to the movement that might be caused by excessive winding.
Suspended mobile power-reserve cone
The highly sophisticated power-reserve indication device warranted a patent in its own right. A truncated cone moves up and down along an arbor connected to the barrel. This suspended cone is topped by a feeler spindle in the form of a mobile arm tipped with a watch jewel. Its position on the cone reflects the state of wind. This feeler spindle is in turn connected to the hand on the power-reserve display, which features graduations engraved on the baseplate and visible through a dial opening. This daring mechanism provides a highly accurate indication of the movement’s power reserve.
Tourbillon with central seconds
Teamed with the seconds wheel and pinion, the tourbillon of Calibre FB-T.FC comprises 67 components assembled within a titanium carriage measuring 16.55 mm in diameter, and fixed to an arrow-shaped steel arch whose tip points towards the space between the barrel and the fusee. A large variable-inertia balance-wheel is regulated and balanced by four gilded nickel silver inertia-blocks. It is coupled with a self-compensating regulating balance-spring in a stainless alloy, featuring a Phillips outer terminal curve (overcoil) manually shaped by the expert hands of the women serving as balance-spring fitters at Chronométrie FERDINAND BERTHOUD. To poise the escapement’s unbalance, two 18-carat gold inertia-blocks ensure the uniformity of the weights of this large-size tourbillon. This tourbillon contributes to earning Calibre FB-T.FC its chronometer title awarded by the Swiss Official Chronometer Testing Institute (COSC). One particular characteristic makes this tourbillon extremely distinctive: although it performs one rotation per minute, it does not display the seconds. The Chronomètre FERDINAND BERTHOUD FB 1.3 is one of the rare tourbillon models to have a central sweep-seconds hand. The latter is extremely long, slim and made of bronze, displaying the seconds with extreme accuracy and in a remarkably stable manner.
Within the traditional approach to watchmaking, construction and mechanical structure are inseparable from the choice of materials and the quality of the finishing. In this respect, the movement of the Chronomètre FERDINAND BERTHOUD FB 1.3 is in a league of its own. The bridges of Calibre FB-T.FC are made of non-treated German silver: a copper, zinc and nickel alloy that is particularly brilliant when polished, yet also extremely fragile. Any imperfection is irreparable and the part must be discarded. Nickel silver is also distinguished by its warm grey colour easily recognised by connoisseurs.
The stainless steel arrow-shaped tourbillon bridge is decorated with the utmost care: the upper side is specular polished, the flanks are straight-grained, the angles are polished and the underside is circular-grained and smooth polished. All levels of the tourbillon carriage, with its titanium components, are entirely chamfered. Some surfaces are polished, others circular satin-brushed, sandblasted or smooth polished. The lever bridge is entirely chamfered, while its visible side features a specular-polished finish and its invisible side is straight-grained. Further up in the gear train, the power-reserve cone is mirror-polished across its inner surface, while the upper and undersides are circular satin-brushed. Two small steel plates are screwed to the cover of the barrel drum: one bears the watch’s limited-edition number, while the other is left blank to be engraved with the initials of its future owner. The 790-part chain measuring 285 mm long is also entirely hand-finished. The sides and studs are satin-brushed and the flat surfaces are polished.
Whatever their position and their function, these component finishing operations are entirely done by hand using traditional tools, in the workshops of Chronométrie FERDINAND BERTHOUD. The quality control of this finishing is performed at a far higher degree of magnification than usual, under a 6x loupe. Under such intense scrutiny, no detail, however tiny, goes unnoticed. No error, imperfection or insufficiency is tolerated. Such is the horological excellence cultivated by Chronométrie FERDINAND BERTHOUD as part of its unfailing commitment to precision for explorers.
This respect for watchmaking tradition, expressed in resolutely modern terms through FERDINAND BERTHOUD chronometers, will remain the core of future developments from the Maison.