Ferdinand Berthoud FB-1R.6-1

The Chronométrie Ferdinand Berthoud collection welcomes a new model FB-1R.6-1, which comes dressed in an ultra-resistant carburised stainless steel and boasts an original regulator-type display.

Issued in a 20-piece limited edition, this exceptional timepiece houses FB-T.FC.R tourbillon calibre with fusee-and-chain transmission that can be admired through a sapphire crystal case-back and two lateral portholes, offering a unique view inside this outstanding chronometer.

Like the previous editions of the Chronomètre FB 1, its movement is equipped with horological complications inspired by the scientific instruments represented by Ferdinand Berthoud’s marine chronometers.

The appearance of the Chronomètre Ferdinand Berthoud FB 1R.6-1 takes its cues from the Marine Chronometer No. 7 that housed a number of solutions for improving the operating principles of longitude watches. Among them was its display that differed from the usual rules governing regulators – which assign a different place on the dial to the hours, minutes and seconds displays – by the use of a large central seconds hand.

Ferdinand Berthoud FB-1R.6-1

The Chronomètre Ferdinand Berthoud FB 1R.6-1 adds some unusual details and a unique presentation to the aesthetic and technical characteristics of the previous versions. It is still a 44 mm-diameter watch, featuring a less than 14 mm-thick case that sits naturally and comfortably on the wrist.

It is composed of a steel cylinder housing the movement. The molecular structure of this steel has been reinforced by a thermo-chemical process involving the diffusion of vapour-phase carbon, thereby guaranteeing an exceptional surface hardness of 1200 Vickers and making it extremely robust. It is also exceptionally corrosion-resistant and biocompatible.

The case features two octagonal-shaped stainless steel side pieces, giving it a characteristic shape including two lateral portholes at 2 and 11 o’clock – providing a chance to admire the chain-and-fusee mechanism in action. These two openings are complemented by a screw-down stainless steel case-back fitted with glare-proofed sapphire crystal enabling observers to appreciate the high-quality finishing lavished on the FB-T.FC-R movement.

The knurled 9mm-diameter stainless steel crown bearing a black ceramic medallion ensures smooth winding of the movement endowed with a 53-hour power reserve.

Ferdinand Berthoud FB-1R.6-1

The novel construction of the Chronomètre Ferdinand Berthoud IR.6-1 sets it apart from all existing regulator-type displays. Instead of featuring a high-up opening providing a view of the tourbillon and the fourth wheel (driving the seconds) as on previous versions, the Chronomètre Ferdinand Berthoud FB 1R.6-1 has a mostly solid dial.

It is made of nickel silver, vertically satin-brushed by hand and black rhodium-plated. Of the three small apertures, the first serves to show the hours, offset at 2 o’clock and appearing on a glare-proofed sapphire crystal disc bearing transferred Arabic numerals striking a pleasing contrast with a white background.

The second opening features an original power-reserve display mechanism, distinguished by a large dial cut-out revealing part of the finely sandblasted and black rhodium-plated mainplate.

Located in the centre of the finely chamfered, bead-blasted and black rhodium-plated minutes counter, the third aperture displays a hand-engraved “pyramid” motif inspired by an open-worked Ferdinand Berthoud astronomical clock belonging to the L.U.CEUM collection. Meanwhile, the seconds appear around the rim of the dial on a flat inner bezel ring made of black rhodium-plated, bead-blasted and chamfered nickel silver.

Ferdinand Berthoud FB-1R.6-1

Finally, the nature and provenance of the Chronomètre Ferdinand Berthoud FB 1R.6-1 can be read off on this large dial, engraved with the inscription “Chronomètre Val-de-Travers Suisse”.

A patent has been filed for the extremely sophisticated power-reserve indication mechanism. Visible through a cut-out in the half-bridge on the case-back side, 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. The latter’s position on the cone reflects the barrel’s state of wind.

Ferdinand Berthoud FB-1R.6-1

The feeler spindle in turn transmits the quantity of energy accumulated by the mainspring to a set of finely chamfered and rhodium-plated flat levers visible through a cut-out in the regulator plate. Its role is to amplify the displacement of the power-reserve hand.

A spiral spring placed at the far end of its travel exercises a force on the base of the power-reserve hand. This spring serves to compensate for the play between the various components of this mechanism and to display the power reserve with peerless precision.

A number of complex mathematical calculations and various tests served to fine-tune the geometry of this spring, made from a nickel-phosphorous alloy in order to guarantee the concentric deployment of the coils in all states of winding and unwinding, and thereby to avoid any unattractive distortion that might also be detrimental to the smooth running of the mechanism.

Ferdinand Berthoud FB-1R.6-1

The FB-T.FC.R calibre is built according to a unique architectural concept. This hand-wound movement features 18 nickel silver bridges framed by polished titanium pillars surrounding the mechanical organs. This construction is typical of 18th century marine chronometers. The architectural approach is picked up in the design of all the components, and especially in the symmetrical equilibrium of the movement.

The distinctive nature of the FB-T.FC.R calibre lies in its inverted upside-down barrel and fusee, and particularly in the fact that both elements are suspended, meaning held on only one side. A patent has been filed for this construction which saves precious millimetres. At 9.89 mm thick, the movement of the Chronomètre Ferdinand Berthoud FB 1R.6-1 thus remains extremely thin for its category despite the regulator-type display and the new power-reserve indication.

When the mainspring is combined with a fusee, the barrel drum turns in one direction when the spring is unwinding and in the other when it is winding, hence serving to coil the chain. The movement generally stops while this type of mechanism is being wound. To prevent this, the FB-T.FC.R calibre is equipped with a differential gear based on an original concept and for which patent has also been filed. It enables the balance wheel to continue oscillating during winding and thereby maintain the movement’s precision timekeeping properties.

The winding mechanism is fitted with a pinion featuring cone-shaped toothing. Coupled with a large-diameter knurled crown, it enables smooth movement winding.

As typically found on chain and fusee mechanisms, the barrel of Calibre FB-T.FC.R is equipped with a “Maltese Cross” stopwork device. The latter serves to limit the winding turns of the mainspring to around six, so as to use only the most stable portion of this spring. This device also acts as a buffer when the barrel is fully wound. At that point, the mainspring torque exerts a 3 kg force, which is considerable for the chain components measuring just a few millimetres.

To perfect the security of the movement, the engineers at Chronométrie Ferdinand Berthoud have equipped the crown with a dynamometric function serving to avoid any damage to the movement that might be caused by excessive winding.

Teamed with the fourth (seconds) wheel and pinion, the tourbillon of Calibre FB-T.FC-R comprises 67 components assembled within a titanium carriage measuring 16.55 mm in diameter, and fixed to a perfectly hand-polished and chamfered arrow-shaped steel arch whose tip points towards the space between the barrel and the fusee. To poise the escapement’s unbalance, two 18-carat gold inertia-blocks ensure the uniform spread of the weights of this large-size tourbillon.

This tourbillon contributes to earning Calibre FB-T.FC.R its chronometer title awarded by the Swiss Official Chronometer Testing Institute (COSC).

One particular characteristic makes the tourbillon extremely distinctive: although it performs one rotation per minute, it does not indicate the seconds, since the Chronomètre Ferdinand Berthoud FB 1R.6-1 is one of the rare tourbillons to have a central sweep-seconds hand. Extremely long, slim and made of gilded bronze, the latter moves with remarkable accuracy and in a remarkable stable manner.

Ferdinand Berthoud FB-1R.6-1

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 1R.6-1 is in a league of its own. The bridges of Calibre FB-T.FC.R are made of untreated nickel silver, a copper, zinc and nickel alloy that is distinguished by its warm grey colour.

The watch case is made with ultra-resistant carburised steel, based on a high-tech thermos-chemical surface treatment. It consists of diffusing carbon into a steel substrate, thereby increasing the hardness of the alloy without destroying its initial properties. In this instance, it reaches the record figure of 1200 Vickers, making the Chronomètre Ferdinand Berthoud FB 1R.6-1 exceptionally scratch-resistant.

The choice of this type of steel, currently used in the aerospace industry, is a nod to the maritime expeditions achieved using the Marine Chronometers produced by Ferdinand Berthoud in the 18th century and which required the use of extremely sturdy materials.

Ferdinand Berthoud FB-1R.6-1

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 angels are polished and the underside is circular-grained and smooth-polished.

All levels of the titanium tourbillon bridge are entirely chamfered. Some surfaces are polished, others circular satin-brushed, sandblasted or smooth-polished. The lever bridge is completely chamfered and its visible side features a specular-polished finish while its hidden side is straight-grained. The power-reserve cone is mirror-polished.

The two bridges framing the tourbillon of the Chronomètre Ferdinand Berthoud FB 1R.6-1 feature cut-outs. Through one of these apertures, the baseplate has been engraved with the same pyramid pattern as the hours dial, while the other reveals the power-reserve cone in all its splendour.

The barrel and fusee are gilded, creating a pleasing contrast with the rough nickel silver and titanium which are omnipresent in the movement. The 790-part stainless steel chain measuring 285 mm long is also entirely hand-finished. The sides and studs are satin-brushed and the flat surfaces are polished.

Whatever the position and function of the components, these finishing operations are entirely done by hand using traditional tools in the workshops of Chronométrie Ferdinand Berthoud.

Technical details

Model: REF. FB 1R.6-1
20-piece stainless steel limited numbered edition

Case in ultra-resistant carburised stainless steel, fitted with two transparent sapphire crystal portholes
Total diameter:  44 mm
Thickness: 13.95 mm
Water resistance: 30 metres
Crown diameter: 9 mm
Numbered edition:   01/20 to 20/20
Dynamometric crown (uncoupling system) in stainless steel, with black ceramic medallion
Screw-down stainless steel case-back fitted with a glare-proofed sapphire crystal
Domed and arched sapphire crystal, with anti-reflective treatment on both sides

Regulator plate (dial) in black rhodium-plated nickel silver, satin-brushed by hand
Hours indication on a sapphire disc at 2 o’clock
Minutes subdial at 12 o’clock, cut-out, bead-blasted, rhodium-plated and bearing black Arabic numerals
Flat seconds inner bezel ring, in bead-blasted black rhodium-plated nickel silver
Power-reserve indication at 10 o’clock engraved on the regulator plate “0-1” and coloured in grey

Dagger-shaped facetted and open-worked minutes hand in 18-carat white gold with blue CVD coating
Steel fixed hour-marker with blue CVD coating
Gilded steel arrow-shaped power-reserve hand
Gilded bronze central sweep-seconds hand

Hours on a disc at 2 o’clock, pointer-type date display at 12 o’clock, central sweep-seconds hand and power-reserve indicator at 10 o’clock

Mechanical hand-wound Calibre FB-T.FC.R
Diameter:  35.50 mm
Thickness:  9-89 mm
Lines: 15 ¾
Jewels:  49
Frequency: 21,600 vph (3 Hz)
Power reserve: approx. 53 hours env.

Chain-and-fusee tourbillon (constant force)
– Suspended fusee – winding differential system (PATENT)
–  Suspended barrel – Maltese Cross stopwork system (PATENT)
– Suspended power-reserve – mobile cone system (PATENT)
– Tourbillon with direct-drive seconds hand (PATENT)
Regulator-type display
Power-reserve indicator with levers and spiral spring
Variable-inertia balance comprising four rhodium-plated nickel silver inertia weights
Balance spring with hand-crafted Phillips terminal curve (stainless steel)
Swiss lever escapement
Cut-out and engraved nickel silver half-bridges, secured to polished stylised titanium bridges
Hand finishing meeting the highest watchmaking standards

Components:  1,158 (including the chain)
Chain:  790 components
Chain length: 285 mm
Half-bridges: 18
Pillars: 6

Rotation:  1 /minute
Components: 67
Tourbillon carriage: Ø 16.55 mm (titanium)
Tourbillon carriage affixed to: 3 polished titanium pillars
Tourbillon carriage poised by: 2 inertia-blocks in 18-carat gold
Balance wheel: Ø 12 mm (copper-beryllium)

Officially chronometer-certified by the COSC

Rolled-edge hand-sewn alligator leather strap made from a single piece of leather (115 x 75 mm with a 20 mm buckle)
Various sizes available on request
Length-adjustable double-blade titanium folding clasp
Pin buckle available on request


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