Adding a GMT function; it might look simple but it presented a challenge that was hard to meet.
Adding a GMT function; it might look simple but it
presented a challenge that was hard to meet.
The single component that made it all possible
When Caliber 9F was first created in 1993, the designers and engineers already knew full well that international travelers would prefer that its extraordinary precision would be preserved when the watch was taken to a new time zone. Indeed, the designers had wanted to include a GMT function which would make this possible from the very start. Nobuhiro Koike, who led the 9F86 development team, explains the thinking as follows:
“When you go to a country in a different time zone, you adjust your hour hand to the local time. This might not present an issue for a regular watch, but for the 9F caliber, we’re speaking about seconds per year accuracy. Even if the watch has been set to be accurate to the second, when the crown is drawn out to adjust the time, the watch stops and consequently loses time. In order for it to maintain the extremely high accuracy we worked so hard to achieve, we thought that a good approach would be to include a GMT function that allows the hour hand to be adjusted while the watch is moving.”
Koike speaks with authority on this as he was a member of the original Caliber 9F development team in the 1990s and it is easy to imagine his, and the team’s, frustration when they found that this was technically impossible at the time. Caliber 9F’s Instant Date Change Mechanism and the independent hour hand adjustment function that is synchronized with it both required a small leaf spring called a jumper, but the team was unable to make the hour hand side of the jumper strong enough.
Twenty-five years went by. Koike, now charged with the development of a new 9F caliber, had never given up his GMT dream but still the problem remained; he needed a jumper with the right amount of strength. He knew that traditional manufacturing methods could not allow this component to be made in the shape he desired, making it impossible to achieve the strength required. So he entrusted the task of finding a solution to the component production technology team of the Shinshu Watch Studio. By 2018, they had achieved what had so long eluded the original team.
“The key to our development of Caliber 9F86 was entirely in the hands of this tiny component. We cannot yet reveal how it was made, but I personally believe that Caliber 9F is now even closer to perfection with the completion of the GMT function,” says Koike.