The Grönefeld One Hertz features a completely original in-house developed movement indicating hours and minutes on a sub-dial at 2 o'clock, a large sub-dial for the deadbeat seconds filling the majority of the dial with a power reserve indicator at 12 o'clock, and a setting-winding indicator at 3 o'clock. Setting-winding is ergonomically selected by pushing the crown instead of pulling it out.
With the One Hertz's unique secondary gear train, Tim and Bart Grönefeld have re-positioned the deadbeat seconds complication where it originated, i.e. on the pedestal of high precision.The quartz-like movement of the large second hand of the One Hertz subtly signals its unique mechanism, invisible to most, but obvious to haute horlogerie aficionados who will appreciate the flawless fine-finishing of the in-house developed calibre G-02.
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The One Hertz launched in 2010 with a subscription-only limited edition of 12 pieces in steel called the "One Hertz 1912" – 1912 was the year Tim and Bart's grandfather qualified as a watchmaker. 2011 heralded the One Hertz Dune, a Limited Edition of 20 pieces in red gold and 2012 saw the launch of the One Hertz Platinum in a Limited Edition of 10 pieces.
The One Hertz Platinum sees the One Hertz – the world's first and only production wristwatch with independent dead seconds – receive an exclusive platinum case and cool blue dial.
The One Hertz Platinum features Grönefeld’s own proprietary movement. All 285 parts of the movement are hand decorated to the highest standards. The One Hertz indicates hours and minutes on a sub-dial at 2 o'clock; large sub-dial for the dead seconds; power reserve indicator at 12 o'clock; and an innovative setting-winding indicator at 3 o'clock.
This ensemble of indicators is all the more striking thanks to the sophisticated blue dial background, which perfectly complements the regal tones of the precious metal platinum case.
The Grönefeld family name has been steeped in the art of watchmaking for a century. It was in 1912 that Tim and Bart's grandfather qualified as a watchmaker, so it is only fitting that exactly one hundred years later, the One Hertz Platinum was launched at Baselworld 2012 in a Limited Edition of 12 pieces.
History of Dead Seconds
With the introduction of the pendulum in the 17th century, clocks finally became accurate enough to measure seconds. It was then not long before a hand indicating seconds on a long clock’s dial signified a precision timepiece. A pendulum with a period – the time to swing forward and back – of two seconds (the most common) resulted in a single tick per second.
The invention of the balance spring, which replaced the pendulum, enabled miniaturization. As portable pocket watches became more accurate, watchmakers naturally thought to copy the one-second steps of the second hand which signified a precision timepiece; however, the rapidly oscillating balance meant that it could not be directly driven as with the pendulum, so it required either a new mechanism if independent, or be driven from another complication e.g. constant force device. While pocket watches have featured independent dead seconds in the past, the Grönefeld One Hertz was the first wristwatch featuring independent dead seconds.The Grönefeld One Hertz is unique among wristwatches in that its dead seconds are powered by a secondary gear train independent of the gear train for the hour and minute indications.
One Hertz
The hertz (symbol: Hz) is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. This SI unit is named after Heinrich Hertz. One Hertz simply means “one cycle per second”.
The second (SI symbol: s), sometimes abbreviated sec., is the name of a unit of time, and is the international base unit of time. To highlight the SI seconds, the One Hertz displays dead seconds with a large seconds hand in its own dial. Hours and minutes are non-SI units of time because they do not use the decimal system so are displayed separately.
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Mechanical wristwatch movements often have balance frequencies of 2.5 to 5 hertz, which results in the seconds hand making tiny steps of 5 to 10 steps each second and looking like a smooth movement. The second hand of the One Hertz is either stationary (dead) or jumping in a full one-second increment each second.
The second (SI symbol: s), sometimes abbreviated sec., is the name of a unit of time, and is the international base unit of time. To highlight the SI seconds, the One Hertz displays dead seconds with a large seconds hand in its own dial. Hours and minutes are non-SI units of time because they do not use the decimal system so are displayed separately.
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The “One Hertz” independent dead seconds complication
Displaying dead seconds in a wristwatch without a constant force device is no easy task. The friction of the mechanism has to be absolutely minimal so it does not interfere with the escapement.
Tim and Bart Grönefeld used an independent dead seconds mechanism that is driven from its own secondary gear train with its own power supply. The seconds are driven from one mainspring barrel and the hours and minutes from another. Friction is with this system guaranteed to an absolute minimum and the complication has no adverse influence on the escapement and free sprung balance.
The two mainspring barrels are wound simultaneously from the crown, which features an innovative “push to set”, “push to wind function”, with the mode selected indicated on the dial at 3 o’clock. A power reserve indicator at the top of the dead seconds dial keeps track of the 72 hours of autonomy.
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Technical Specifications
Model: One Hertz Platinum
Calibre G-02, mechanical hand winding, independent deadbeat seconds, power reserve indicator and setting indicator
Movement
Number of parts: 285
No.of jewels: 39, set in gold chatons
Power reserve: 72 hours
Balance wheel: 9.12mm free-sprung variable inertia balance wheel
Frequency: 21’600 bph/3 Hz
Balance spring: Phillips terminal overcoil curve
Deadbeat seconds mechanism: Independent mechanism, cam with 30 teeth on the going gear train on the seconds wheel, escape wheel on the seconds wheel of the independent gear train
Case and dial
Material: platinum. Limited edition of 12 pieces
Dimensions: 43mm x 13mm
Water resistance: 3atm/ 30m/ 100feet
Dial: Hour and minutes sub-dial, seconds sub-dial, power reserve indicator, setting-winding indicator
Hands: Hours and minutes, long thin counter-poised seconds, power reserve and setting-winding
Strap and buckle
Movement
Number of parts: 285
No.of jewels: 39, set in gold chatons
Power reserve: 72 hours
Balance wheel: 9.12mm free-sprung variable inertia balance wheel
Frequency: 21’600 bph/3 Hz
Balance spring: Phillips terminal overcoil curve
Deadbeat seconds mechanism: Independent mechanism, cam with 30 teeth on the going gear train on the seconds wheel, escape wheel on the seconds wheel of the independent gear train
Case and dial
Material: platinum. Limited edition of 12 pieces
Dimensions: 43mm x 13mm
Water resistance: 3atm/ 30m/ 100feet
Dial: Hour and minutes sub-dial, seconds sub-dial, power reserve indicator, setting-winding indicator
Hands: Hours and minutes, long thin counter-poised seconds, power reserve and setting-winding
Strap and buckle
Hand-sewn matte black, alligator leather with engraved platinum folding buckle
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