close search

Grönefeld One Hertz with Independent Deadbeat Seconds

June 29, 2010


The Grönefeld One Hertz is the second complicated mechanical timepiece created by Swiss trained, Netherland based watchmaking brothers, Bart and Tim Grönefeld. The movement for this new timepiece, was created completely in-house. The dial indicates hours and minutes on a sub-dial at 2 o'clock. Power reserve is indicated at 12 o'clock.

What really makes this timepiece standout, is the deadbeat seconds, which is indicated by the large off-centre sub-dial. Independent deadbeat seconds, rotate the dial (independent means the seconds are displayed in the sub-dial) by ticking forward, much like on a traditional quartz movement. Except that this is, of course, a mechanical movement, which really makes it complicated to produce. In fact, this is the world's first and only mechanical timepiece with independent deadbeat seconds.

Press Release

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.

The One Hertz launches 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.


The name Grönefeld and the art of watchmaking have a family history spanning nearly one hundred years, originating in the small and ancient town of Oldenzaal located in The Netherlands. It is there, in a shop directly under the view of the ancient basilica church and its tower dating from 1240, that the grandfather of the present watchmakers, Johan Grönefeld, began his career as a watchmaker in 1912.

This marked the beginning of the small and highly talented dynasty of Grönefeld watchmakers, which reaches to the present day with the brothers Bart and Tim Grönefeld. Their workshop is located in the same building as that used by Johan Grönefeld, representing a continuous, unbroken watchmaking family history that is exceptionally rare to find anywhere in the world today.

Both Tim and Bart Grönefeld underwent extensive training in Switzerland, and within a relatively short span of time proved themselves adept world specialists in the production of the most coveted and exquisite horological compications of all: the tourbillon and the minute repeater wristwatch. in 2008, after working anonymously behind the scenes for prestigious Swiss brands, they presented the first watch bearing their own name, the GTM-06 Tourbillon Minute Repeater.


comments powered by Disqus