Wearables

Grand Seiko Kodo with world-first combination of high-accuracy devices

Grand Seiko Kodo with world-fi...
The Grand Seiko Kodo
The Grand Seiko Kodo
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The Grand Seiko Kodo
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The Grand Seiko Kodo
The Kodo Constant-force Tourbillon combines a tourbillon and a constant-force mechanism in a single unit
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The Kodo Constant-force Tourbillon combines a tourbillon and a constant-force mechanism in a single unit
Diagram constant-force and tourbillon combined
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Diagram constant-force and tourbillon combined
Kodo front
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Kodo front
Kodo reverse
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Kodo reverse
The Kodo comes in a limited edition
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The Kodo comes in a limited edition
The Kodo has a platinum and titanium case
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The Kodo has a platinum and titanium case
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Grand Seiko has released its first mechanical complication watch, the Kodo Constant-force Tourbillon, which is the first timepiece to combine a tourbillon and a constant-force mechanism into a single axis for greater stability and accuracy.

A constant-force mechanism is an important part of a mechanical watch movement that smooths out how it works and keeps it on time. Anyone who has played with a wind-up toy has seen how it starts moving quickly and slows down as the spring unwinds. The same is true in a watch. If the mainspring was connected directly to the gears, the hands would initially spin around like mad, then stop after a few minutes.

To keep this from happening, movements have escapements, which oscillate and stop the movement for an instant one or more times per second. Theoretically, this should make the watch keep time but in practice, things are very different. When the spring is wound, it exerts a lot of force, but as it unwinds, the pull becomes progressively weaker.

Diagram constant-force and tourbillon combined
Diagram constant-force and tourbillon combined

This sets up forces that throw the escapement off and the timepiece becomes less accurate. To prevent this, a constant-force mechanism is introduced that sits between the mainspring and the escapement, evening out the energy of the spring so it's released at a constant rate on a constant level.

Until now, if a watch had a tourbillon and a constant-force mechanism, they are in different parts of the movement and only interact through the gearing. In the Kodo, these are, for the first time, joined together on the same axis. It's a design that Grand Seiko introduced in 2020 with the T0 Constant-force Tourbillon concept, but has now been incorporated into a finished watch in the form of a movement that is smaller than the concept prototype.

The Kodo Constant-force Tourbillon combines a tourbillon and a constant-force mechanism in a single unit
The Kodo Constant-force Tourbillon combines a tourbillon and a constant-force mechanism in a single unit

According to Grand Seiko, this new arrangement simplifies the movement. Since there aren't any gears between the tourbillon, which vibrates at eight beats per second, and the constant-force mechanism, which rotates at precise one-second intervals, there is no loss or change in torque, allowing for greater endurance and a stable amplitude of the balance.

It also allows the constant-force carriage to act as a small seconds hand as it turns.

The Grand Seiko Kodo Constant-force Tourbillon SLGT003 is powered by the 340-component, 44-jewel, manual Caliber 9ST, running at 28,800 vibrations per hour (eight beats per second) and is accurate to +5 to -3 seconds per day. The mainspring has a power reserve of 72 hours.

The Kodo comes in a limited edition
The Kodo comes in a limited edition

This movement is set in a case made of Platinum 950 and Brilliant Hard Titanium with a box-shaped sapphire crystal with anti-reflective coating and a sapphire case back, giving it a water resistance to 330 ft (100 m, 10 bar). This is held on by a calf-leather strap with a Platinum 950 three-fold clasp with push-button release. If you don't like that, a double-sided crocodile strap is also included.

The Grand Seiko Kodo Constant-force Tourbillon will be available in a limited edition of 20 units starting in October 2022 and one will set you back US$350,000.

The video below introduces the Grand Seiko Kodo Constant-force Tourbillon.

Kodo

Source: Grand Seiko

View gallery - 7 images
3 comments
3 comments
StanislawZolczynski
Effectively this watch has jumping second which is a normally separate complication
DavidB
Given the ubiquity of cellular phones with constantly adjusted, highly accurate time readily accessible, wristwatches have become little more than jewelry, making $350K an entirely appropriate price for a status symbol and an utterly unacceptable price for a practical tool.
Eddy
I wonder how many wearers of this extravaganza poking out of their starched and gold cufflinked shirtsleeves will be comparing the time with their phone display.