GREUBEL FORSEY Invention Piece 1

The Invention Piece 1 embodies Robert Greubel and Stephen Forsey’s wish to honour the Double Tourbillon 30° and to raise the bar yet another notch by opening up whole new vistas for their first major invention. Both the architecture of the movement and the display of information symbolise the four years of meticulous research that the Inventor Watchmakers have devoted to developing the new mechanism.

In this Invention Piece 1, the creative Greubel Forsey twosome has rearranged the volumes and surfaces of the timepiece according to a new technical and aesthetic structure. The latter places the Double Tourbillon 30° at the centre of a semi-circular hour and minute display, thereby visually reinforcing the link between the mechanism responsible for measuring the time and its “symbolic” indication.

Compared with the Double Tourbillon 30°, the movement driving the Invention Piece 1 has been profoundly modified to off-centre the double cage by shifting it slightly to the left and distinctly higher. This position freed up space to place the object of the invention at the very centre of the highly original hour and minute display. Two triangular indicators – a red one for the hours and a blue one for the minutes – enable the observer to follow the passing of time on the mechanism’s two concentric semi-circles. To facilitate read-off, the 12-hour and 0-minute markers are aligned at the traditional 12 o’clock position.

Magnificently evoking the mechanical genius of the Invention Piece 1, the various speeds of rotation of these different elements give an idea of the complexity of the mechanism: whereas the outer cage takes four minutes to perform a complete rotation and the inner cage just 60 seconds, the double hands turn in 24 hours for the hours display and two hours for minutes. Around the tourbillon with its indicators, the absence of a dial reveals the frosted nickel silver bridges that are clearly visible on three distinct levels. This opening provides a view of the concentric gearing serving to drive the hour and minute indicators.

The off-centred small seconds and power-reserve displays are reminiscent of a miniature solar system. While the case with its signature Greubel Forsey lugs is immediately recognisable, this Invention Piece 1 expresses its unique nature, reinforced by an unexpected detail: directly engraved on a plate appearing on the case-back, a unique message from the Inventor Watchmakers will forever accompany the owner of this exceptional timepiece. 388 parts contribute to the smooth running of the movement driving the Invention Piece 1, including 128 for the double cage that weighs just 1.17 grams.

The Invention Piece 1 is produced in a single edition comprising three versions of 11 watches each, a number chosen for its symbolic value representing the Robert Greubel and Stephen Forsey partnership.

Technical details
Movement
Movement dimensions
• Diameter: 36.4 mm
• Thickness: 12.72 mm
Number of parts
• Complete movement: 388 parts
• Tourbillon cage: 128 parts
• Weight of the cage: 1.17 g
Number of jewels: 38; Olive-domed jewels in gold chatons
Power reserve: 72 hours
Barrels: Series-coupled fast-rotating double barrel (1 turn in 3.2 hours), equipped with a slip-spring to avoid excessive tension
Balance wheel: Free sprung balance with white gold mean-time screws (10.7 mm diameter)
Frequency: 21’600 vibrations/hour
Balance spring
• Phillips terminal curve
• Geneva-style stud
Main Plates: Spotted and frosted nickel silver
Bridges: Frosted and gold-finished nickel silver,“Message from the Inventor Watchmakers” text in relief on a gold plate

Gearing
• Involute circle profile
• Conical gearing with corrected profile

Inner Tourbillon
• Inclined at a 30° angle, 1 rotation per minute

Outer Tourbillon
• 1 rotation in 4 minutes
• Hand-bevelled and open-worked cage pillars
• Solid gold counterweight plate

Displays
• Hours and minutes
• Small seconds
• 72-hour power reserve on a sector

Case
• In gold or platinum with convex sapphire crystal, 3 versions in series of 11 each
• Transparent back with convex sapphire crystal
• Raised engraving of the name of the Invention on a hand-punched background
• Gold security screws
• Hand-engraved individual number

Case dimensions
• Diameter: 43.5 mm
• Thickness: 16.64 mm
Water resistance of the case :3 ATM – 30 m – 100 ft
Crown :Gold with engraved and black lacquered GF logo

Hands
• Hours (red triangle) and minutes (blue triangle) • Small seconds
• Power-reserve pointers in flame-blued steel

Strap
Hand-sewn black or brown alligator leather with gold folding clasp, hand-embossed with the Greubel Forsey initials

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