Grand Seiko Kodo Constant Force Tourbillon SLGT003

Grand Seiko copy amazes the audience of Watches & Wonders with the world’s first tourbillon and single-axis constant-force mechanism.

This is Grand Seiko’s debut at Watches & Wonders, and the Japanese brand amazes the crowd with its stunning Kodo Constant Force Tourbillon SLGT003. What was once a concept movement launched in 2020, is now the Kodo Constant Force Tourbillon, with a radically skeletonized design that showcases its mechanical excellence and transmits the sound of its beating heart. Not only does this watch mark Grand Seiko’s first mechanical complication in its 62-year history, but it is also the first watch in the world to combine a tourbillon and a constant-force mechanism on a single axis.

A watch with such mechanical ingenuity and complexity did not appear suddenly. Two years ago, Brice reviewed the Grand Seiko T0 constant force tourbillon movement, the brand’s first tourbillon with a constant force mechanism and the predecessor of the new caliber 9ST1. Although tourbillons are common in high-end watchmaking, Grand Seiko’s movements are revolutionary in combining tourbillons with a constant force mechanism. Without delving into the history of AL Breguet’s 1801 patented tourbillon mechanism, which was designed to counteract the effects of gravity on the regulating mechanism, other forces could interfere with the timing system, such as changes in the torque of the mainspring. To ensure continuous power, watchmakers invented the fuselage chain and the remontoire d’égalité mechanism. Grand Seiko uses a remontoire or secondary spring to power the escapement. However, not one but two springs are placed parallel to the twin barrels to ensure a stable transfer of torque.

Two metals, two mechanisms
The name Kodo, which means heartbeat in Japanese, perfectly describes the watch’s skeletonized design, which allows you to see the beating heart of the Grand Seiko 9STL movement. Not one but two metals make the 43.8mm case, made from Platinum 950 and Grand Seiko’s proprietary Brilliant Hard Titanium. Consistent with Grand Seiko’s reputation for exquisite hand-finishing, the case features a mirror-polished (Zaratsu) area and hairline finish. Despite the attractive cutout displays on both sides, the case is still water-resistant to 100 meters.

After two years of intense work, the team at cheap Grand Seiko‘s new Atelier Ginza in Tokyo has launched its powerful hand-wound calibre 9ST1. Compared to the original concept movement, the engineering of the 9ST1 movement is exceptionally complex, but the idea of ​​integrating the constant-force mechanism and tourbillon as a unit on one axis is relatively simple. Since there are no wheels or other components between the two mechanisms, there is no loss or change in torque transmitted from the constant force mechanism to the balance. This results in an increased duration of the constant force mechanism by 50 hours and a more stable amplitude of the balance wheel. Together these characteristics provide a very stable movement accuracy, rated +5 to -3 seconds per day.

Viewed on the dial, the inner tourbillon cage rotates with the balance wheel vibrating 8 times per second, and the outer constant-force cage follows its rotation at precise one-second intervals. Hours and minutes are displayed on a subdial at noon; a power reserve indicator at 8 o’clock and a small seconds on the tourbillon at 6 o’clock. Dark areas are interrupted by bright pink rubies and many different finishes, the movement of the 340 part is very modern. cheap men watch

In addition to the visual spectacle, the sound of the escapement and the pulse of the constant force mechanism once per second can also be heard. Since the movement’s current record is the highest frequency ever recorded (4Hz), combined with a constant force mechanism, the sound is set to a 16th or half-eighth note.

Light entering the case from the front and back illuminates the highly handcrafted components decorated with subtle shade gradients, angles and textures. The limited edition number 00/20 is engraved on the caseback.

The Grand Seiko SLGT003 comes with a black calfskin strap that is hand-painted in a lacquer finish, a technique similar to the wear-resistant material used to make samurai armor. The strap features a platinum triple-folding clasp with push-button release. A double-sided alligator leather strap is also included in the package.

Technical Specifications – GRAND SEIKO Constant Force Tourbillon SLGT003
Case: 43.8mm diameter x 12.9mm thickness x 50.6mm lug to lug – Platinum 950 and Brilliant Hard Titanium, hand-brushed and Zaratsu polished finish – Box sapphire crystal with anti-reflective coating on the dial, see – Through the case back – 100m waterproof
Dial: Skeleton – Dial showing hours and minutes at noon – Integrated constant-force mechanism and tourbillon at 6 o’clock – Power reserve indicator at 8 o’clock
Movement: Grand Seiko 9ST1 Caliber – Manual Winding Constant Force Tourbillon – 35mm x 7.98mm – 340 components – 28,8000vph/4Hz – Accuracy +5 to -3 seconds per day – 72 hours power reserve (50 hours constant force)
Strap: Black calfskin strap, lacquered – Platinum triple folding clasp with push-button release – Additional alligator strap available
Reference: SLGT003