The creativity of learning from the past to connect Grand Seiko to the future

Interior and exterior highlights for the 20th anniversary of Spring Drive

Spring Drive has now become an essential "engine" for Grand Seiko. To celebrate its 20th anniversary, Seiko has added two new collections to the Grand Seiko line: the Elegance Collection, which pursues high-end style, and the Sports Collection, which is limited edition and features a lion design motif. Both collections breathe fresh air into Grand Seiko, and serve as a "bridge" connecting Grand Seiko to the future as it celebrates its 60th anniversary next year.

　Released in 1999, Spring Drive was a completely new mechanism that combined the powerful torque of a mechanical watch with the high precision of a quartz movement. Additionally, this mechanism boasted complete silence and sweeping movement. To emphasize the unique character of Spring Drive, Seiko Epson's development team began to refine the Spring Drive. Since then, the company's luxury watchmaking division, Micro Artist Studio, has released a succession of masterpieces, including the Credor Spring Drive Sonnerie and Eichi.

　In 2019, marking the 20th anniversary of the birth of Spring Drive, Seiko released a model that could be considered the culmination of its efforts. It is called the Grand Seiko "Elegance Collection Spring Drive 20th Anniversary Model." Micro Artist Studio has poured all of their current technical expertise into this model. It is equipped with the new hand-wound caliber 9R02. This is an improved version of the 7R14 used in the "Eichi II," boasting a longer power reserve and superior finish.

SBGZ003

　For a while after the mainspring is fully wound, there is a margin of torque. Therefore, the mainspring winds itself using approximately 30% of the mainspring torque, which does not affect accuracy or hand movement. This is the outline of the torque return system adopted in this model. Additionally, by using a dual spring barrel with two mainsprings stacked vertically, the 9R02 has a long power reserve of approximately 84 hours. Normally, stacking the mainspring vertically increases the thickness of the movement. However, by minimizing the width of the two mainsprings, the developers were able to minimize the barrel's protrusion.

The Torque Return System (TRS) was developed by Seiko Epson and installed in the Cal. 7R08 of the Eichi, released in 2008. In the Cal. 9R02, the mainspring's unwinding force is used to rewind it, extending the power reserve up to 48 hours, while the mainspring still has torque. The TRS is linked to the power reserve mechanism, and after 48 hours, a protrusion on the sun wheel activates the TR disconnect lever, which disengages the torque return wheel clutch and cuts the connection between the barrel and ratchet wheel. This mechanism can also be adapted for use in mechanical watches.

　Micro Artist Studio's signature finishing has also been further refined. Specifically, the new 9R02 combines the intricate chamfering of the Credor Eichi with the deep chamfering of its successor, the Eichi II. The bridge is made of nickel silver, the same as previous Micro Artist Studio movements. However, by reducing the number of surface serrations from multiple to one, the chamfering width remains deeper and the sagging of the edges is minimized. Furthermore, by using a "special technique," the chamfering is almost completely polished black. There's more to be said. The shock-absorbing spring is serrated, and the 18K gold frame that supports it has been given a perfect mirror finish. Honestly, no Japanese-made movement has ever been finished to this level.

　The exterior that encases this outstanding movement is equally elaborate. The hands and indexes of this model are made of 14K white gold, not brass. While there have been models in the past that have used gold indexes, this time the rhodium plating surface treatment has been deliberately omitted. The reason is to take advantage of the texture of solid gold and show off sharper edges. Even though the plating is layered, it is only a few microns thick. However, the creators disliked even that slight thickness in order to emphasize the edges of the hands and indexes. As a result, the sharp edges of the hands and indexes are unlike any other.

　The logo and the minute and second markers are also elaborately crafted. They are not pressed, etched, or hand-engraved, but deliberately machine-engraved. As you can see in the photo, there are no visible billets, or cutting marks. Other companies have also adopted this technique, but this is likely the first time we have seen one with no traces at all.

　The SBGZ001 also incorporates a new approach to the case. The dial has the familiar snow-white finish of Spring Drive watches. It is pressed to recreate the wind-etched snow. This time, the same snow-white finish has been applied to the entire case. However, pressing is not possible on a three-dimensional case. Therefore, craftsmen carve out individual lines to create a sense of unity with the dial. The finish seen on previous Grand Seiko watches has been reproduced on the entire case. If too much is carved out, it cannot be reversed, so each and every work is a complete challenge. Furthermore, carving out the ridges on the side of the case will change the shape. No wonder only 30 pieces can be made.

　This is a platinum-cased limited edition model that Micro Artist Studio has poured everything they have into. Hoshino Kazunori, who was in charge of the design, explained why they went to such lengths: "We are currently unraveling the history of Grand Seiko. We are thinking of recreating the finishes of the past that we have learned from that using current technology. This includes the faceted 14K gold indexes and hands, and the snow-white finish of the case." The Grand Seiko "Elegance Collection Spring Drive 20th Anniversary Limited Edition Model" was born from learning from the past and applying current technology. Its appearance stands out from the crowd.