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The brothers Grönefeld, Bart and Tim, from Oldenzaal in the Netherlands. Two very talented watchmakers from a fine family tradition of watchmaking. Bart and Tim Grönefeld may claim that their grandfather, Johan, began his watchmaking career in the very same location in Oldenzaal in 1912. The brothers enjoy the good fortune to work in their native town, in the very same family workshop now 100 years old!

It’s very uncommon in todays World to find a heritage of watchmaking passed from generation to generation. There are few watchmakers today that may claim this heritage and lineage. Bart and Tim Grönefeld are very proud to be the latest generation to carry the Grönefeld name into the 21st century while raising the bar for the next generation of Grönefeld’s (seen here at the bench).

Bart and Tim both started there careers the way most watchmakers get started, at watchmaking school. In their case, both were fortunate enough to attend WOSTEP Swiss watchmaking school. After WOSTEP Bart worked at prestigious and famous Asprey in London, doing service and restorations. In 1991, Bart Grönefeld began working at Audemars Piguet-Renaud & Papi under the direction and tutelage of Guilio Papi. Renaud & Papi enable haute horology and high watchmaking projects for the grande house of Audemars Piguet. Bart and Tim were both talented and fortunate enough to work for APR&P during the beginning of a great renaissance of mechanical watchmaking.The environment of Renaud & Papi was one of collaborative efforts among the best of the best young talents in the industry. In fact, many fine independent watchmakers that we know today by name and often by brand, gained their most important experiences of their careers under Mr.Papi. At the time Renaud and Papi produced tourbillon and grand complications for Audemars Piguet and other notable haute horology projects during the burgeoning era of modern mechanical watches. Bart eventually oversaw all of assembly and worked at APR&P from 1991 until 1998. Tim worked at APR&P from 1994 until 1998. Tim Gronefeld was responsible for the regulation of tourbillon and escapements.
In 1998, both Bart and Tim felt the pull to return to their home in Holland to work in the family business and live their lives in Holland. The brothers were quick to develop a service business providing top notch after sales service for a few major brands. A business that eventually led to the hire of several other watchmakers to cover the growing work load.

Bart and Tim were keen to make their own mark in the World of watchmaking. Of course, the thought of lending their family name of Grönefeld to the dial of their own watch. Bart and Tim decided to start their own watch company with a very simple first watch, a minute repeater tourbillon! The watch took 4 years of development and also required the development of a bespoke case, designed specifically to highlight and amplify the sound of the minute repeater. The was optimized and the special “cathedral lugs” were designed to be strong in form and hollow, in order to help the resonation of sound from the gong(s). The first fabulous watch became know as the GMT-06.

The GTM-06 in Platinum. A minute repeater tourbillon.

Bart and Tim realized that the development of a watch brand would require a greater diversity in product offering, other than a a bespoke haute horology super watch. So, the brothers began their work on a design concept that would ultimately result in further research and development of a very special watch with a unique goal. The Grönefeld One Hertz is that watch and the goal was to produce a unique calibre to drive a One hertz escapement without constant force. The result required the development of a unique calibre, with 285 hand finished components that feature two separate gear trains. Two gear trains? Yes,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 balanceThe One Hertz features Grönefeld’s own proprietary movement of which all 285 parts 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 One Hertz setting and winding is also extremely ergonomic, selected by pushing the crown in, rather than pulling it out.
Dead seconds – where the second hand advances in full steps of one second instead of an apparently smooth sweeping action – was a very respected mechanical complication until the 1980s. However, its popularity then died with the dominance of quartz movements, which also stepped in full seconds. A smooth sweeping second hand came to differentiate mechanical from quartz.
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.
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.

The Parallax Tourbillon

The Grönefeld Parallax tourbillon features a “flying” tourbillon with a large central seconds hand, stop seconds, power reserve indicator and winding-setting function indicator.The in-house movement, beautiful solid silver dial and highly polished case display sophistication and craftsmanship at the very highest level.The raised flying tourbillon allows full appreciation of the concentric, rhythmic “breathing” of the balance hairspring, while ensuring high precision.The name “Parallax” is derived from the precision of the readability of the central seconds hand. Parallax is defined as the apparent change in position of an object when the observer changes his own position.To minimize the possibility of error due to parallax when viewing the seconds hand from an angle, the hand is exceptionally close to the outer chapter ring with the seconds indexes. In a neat touch, the one-armed balance wheel bridge always runs parallel to the central seconds hand.Rather than pulling the crown to set the time, which has the risk of damaging the fragile crown stem, it is pressed. An indicator on the dial displays the function selected: “W” for winding or “S” for time setting.When the time setting function is selected, both the tourbillon cage-bridge and the central seconds hand automatically continue to their respective 12 o’clock positions where they stop (or hack) while the time is set.Once the time is set and the function set to winding by a simple press of the crown, both the seconds hand and tourbillon cage start running in parallel again.The dial of the Parallax Tourbillon has been crafted out of solid silver. The frosted surface provides a gentle sheen superbly setting off the flamed-blued hands and making for excellent legibility.The graceful curves of the displays are complemented by a multilayered profile endowing the dial with a wonderful sense of depth.The complex dial comprises seven individual components. All applied elements are rhodium plated with circular graining and beveled edges.The bevels are polished with diamond paste to a brilliant gloss to create scintillating reflections of light, echoing the high-end finishing of the stainless steel movement bridges visible through the display back.

Parallax Calibre G-03

Bart and Tim Grönefeld use stainless steel bridges exclusively for their movements.As well as the superior hardness and durability of stainless steel compared to the more generally used steel and brass, the metal gleams when polished to a mirror finish.Achieving superlative finishes in stainless steel is no easy task: polishing the hard metal takes a master watchmaker up to four times longer than polishing more commonly used brass.As with the immaculately finished movement bridges, the tourbillon cage is crafted in stainless steel. Three days are required just for the hand finishing of the tourbillon components.A highly-polished stainless steel sleeve around the tourbillon draws further attention to the beautiful escapement by reflecting the oscillating balance wheel and the rotations of the escape wheel and tourbillon cage.Normally a central seconds hand requires a friction spring to prevent small fluttering caused by play in the gear train.But for the Parallax Tourbillon, the Grönefeld brothers developed the movement with an added pinion and wheel so that the energy-sapping friction spring is not required.The latter feature improves power transfer to the regulator, contributing to the impressive power-72-hour power reserve.

For more details :


One Hertz

Parallax Tourbillon

Grönefeld….”The Movie” , Bart and Tim proudly talk about their clockmaking/watchmaking heritage and we get a look around the workshop and a glimpse of what’s done before the components become watches.

Bart Grönefeld, introduces the Parallax Tourbillon to Revolution Magazine @ BaselWorld 2014

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