Most of you may not be familiar with Tim and Bart Grönefeld, but you will be soon enough. They make up Grönefeld Exclusive Timepieces. The two brothers who spent years working behind the scenes at some of the world's most prestigious watch companies are now out on their own, and today we present you their latest creation, the One Hertz 1912.
The One Hertz 1912 is the world's first and only production wristwatch with independent deadbeat seconds. What are deadbeat seconds, you ask? We'll, it basically means the seconds tick, like they would with a quartz movement, except these are obviously mechanically powered. The One Hertz 1912 does deadbeat seconds for the first time on an independent secondary gear train.
So what is the point of deadbeat seconds when the world associates ticking with low-end quartz movements? Well, deadbeat seconds is a complication based on precision. Sweeping second hands are considerably more difficult to read, and a deadbeat complication allows the wearer to quickly and accurately read the number of seconds.
This complication was particularly popular with doctors and nurses, and the Rolex Tru-Beat, a deadbeat watch in the 1960s that to this day is a valuable and rare collectable.
Back to this new watch from Grönefeld; the seconds have been placed prominently in the center of the dial and been given their own registers, as really, the seconds are what this watch is about. It has been named the One Hertz because a "hertz" by definition is one cycle per second, and 1912 is the year the Grönefeld's grandfather became a watchmaker.
We are excited to see a modern haute horology brand tackle the deadbeat, and we look forward to more products from the Grönefeld brothers. Click here for more details.
Displaying deadbeat 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 deadbeat 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 with this system is guaranteed to an absolute minimum and the complication has no adverse influence on the escapement and freesprung 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 deadbeat seconds dial keeps track of the 60 hours of autonomy.
Calibre G-02, mechanical hand winding, independent deadbeat seconds, power reserve indicator and setting indicator
Movement dimensions: 35mm x 9.4mm
Jewels: 39, set in gold chatons
Power reserve: 60 hours
Barrels: Two barrels, one for the going gear train and one for the independent deadbeat seconds mechanism; both barrels are wound at the same speed and in the same direction
Balance wheel: 9.12mm free-sprung Gyromax balance wheel
Balance frequency: 21’600 bph/2.5Hz
Balance spring: Phillips terminal overcoil curve, triangle-style stud
Main Plate: Spotted and snailed rhodium plated nickel silver
Bridges: Stainless steel, hand-bevelled, micro-blasted centre and the underneath spotted, circular grain on the top, relief engraved on micro-blasted surface
Gearing: Two independent gear trains each with their own energy source
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, double lever with jewelled pallets
Winding-setting mechanism: Push function crown for winding or setting
Power reserve mechanism: Classic Breguet style by means of a cone moving up and down on the threaded barrel arbour
Indications: Hours and minutes in sub-dial at 2 o’clock, large seconds at 7 o’clock, power reserve, setting-winding indicator at 3 o’clock
Case and dial
Case: stainless steel, limited edition of 12 pieces, gold security screws, polished bezel and centre band with hand-finished straight graining
Case dimensions: 43mm x 12.5mm
Sapphire crystals: top domed with anti-reflective treatment both sides, display back with anti-reflective treatment inside
Water resistance: 3atm/30m/100feet
Crown: Stainless steel with engraved “G" logo
Dial: Hour and minutes sub-dial, seconds sub-dial, power reserve indicator, setting-winding indicator, Grönefeld logo and model name on individual screwed-down nameplates
Hands: Hours and minutes, long thin counter-poised seconds, power reserve and setting-winding
Strap and buckle: Hand-sewn matte black, alligator leather with stainless steel engraved tang buckle