Grand Seiko T Zero Constant Force T0

Grand Seiko Caliber T0 (T-Zero)

Grand Seiko T Zero Constant Force T0

ManufacturerGrand Seiko
Caliber NumberT-Zero (T0)
Movement TypeTourbillon, manual-wind
In-House?
Yes
Diameter
36mm
Thickness
8.22mm (total)
Jewels43
Components
340
Vibrations Per Hour
28,800 bph
Power Reserve
>50 hours
FunctionsHours and minutes at 12:00, power reserve indicator at 9:00
Features
Dual tourbillon cages at 6:00, dual barrels, constant force device/remontoire
Country of ManufactureJapan

The Grand Seiko caliber T0 (aka T-Zero) is a constant force tourbillon watch movement. The caliber T0 was announced to the world on September, 2, 2020 and is the first tourbillon movement to be released by Grand Seiko. It is also Grand Seiko’s first attempt at creating a constant force mechanism.

The is a concept caliber produced by a design team lead by Takuma Kawauchiya and is not currently available in any Grand Seiko models (there are no finished watches with this caliber). The movement is on display in Morioka, Japan at the Grand Seiko Studio Shizukuishi.

In Grand Seiko’s own words:

“Seiko Watch Corporation revealed the T0 (T-zero) Constant-force Tourbillon (abbreviated as “T0″) as a concept creation of Grand Seiko in September 2020. It represents the world’s first movement with a fully integrated constant-force and tourbillon on the same axis, aiming to create a mechanical watch with the highest accuracy possible. In the 1960s, Seiko’s mechanical movements dominated top spots at the Neuchatel and Geneva Observatory Competitions, regarded as the most authoritative watch competitions then. With this new movement, Grand Seiko returned to the top in the world.” -Grand Seiko

GS also says the T0 movement is “…intended to elevate precision with a complicated mechanism to pursue further accuracy without consideration of mass production.”

Constant Force:

By their nature, mechanical watch movements operate based on the transfer of energy from the mainspring to the escapement. The amount of force needed is variable depending on how much energy remains in the mainspring. For this reason, watches do not keep the exact same accuracy throughout the entire duration of power reserve. This is why testing is done over the span of days to get an average rate of timekeeping.

As Grand Seiko explains:

“A constant-force preserves power in a small spring called a constant-force spring, which is different than a mainspring, and uses the repulsive power of this small spring to power a pendulum or a balance. The mechanism is often compared to an impounding dam and it is excellent in the way that it ensures stable torque.” -Grand Seiko

With constant force technology, an equal distribution of energy is sent to the escapement despite the amount of energy stored in the mainspring. Thanks to the constant force mechanism, the movement will maintain the same rate when fully wound as it would when on its last hour of power reserve.

World’s First:

Grand Seiko is not the first to develop a constant force tourbillon (Arnold & Son, IWC, Andreas Strehler Trans-axial Remontoir Tourbillon), but according to the brand, the T0 is the first movement to incorporate “a fully integrated constant-force mechanism and tourbillon on the same axis.”

Calibers 9S65 and 9SA5 Marketing:

With Baselworld 2020 being cancelled, the watch community is thirsty for new releases and announcements. As impressive and important as this caliber is to the watch world, the launch of the T0 appears to also be serving as marketing material for 9S65 and 9SA5 powered watches.

Grand Seiko states that the T0 is based on the GS caliber 9S65. Furthermore, the official press-release mentions that their Hi-Beat caliber 9SA5 (introduced in August 2020) was inspired by the T0 development. While the T0 is not available, this announcement is a reminder that watches with the 9S65 and 9SA5 are on the market.

From the T10 story:

“It was a natural choice to develop T0 based on Caliber 9S65, which had been tried and trusted. Key components such as the mainspring, the wheel trains, the escapement, and the balance are designed based on those of 9S65. The setting lever and yoke were designed based on 9S65 as well.” -Grand Seiko

“…the pursuit for higher accuracy and the watchmaking technologies including movement finishing of T0 contributed to refining the revolutionary mechanical caliber, 9SA5.” -Grand Seiko

From the official press-release:

“In pursuit of the highest level of accuracy for mechanical watchmaking, the designers conceptualized the new creation without restrictions from production capability considerations. The free approach to development resulted in the birth of T0 and inspired essential movement parts for the new Caliber 9SA5, which was developed in parallel with the concept creation.” -Grand Seiko

16th Note Feel:

On the image below, the back of the movement features text above the tourbillon reading: “16TH NOTE FEEL”.

Grand Seiko T0 16th Note Feel

16th note feel is a drumming reference that Grand Seiko relates to the ticking sound the T-Zero puts out. Because the escapement on the T0 beats at 28,800 vibrations per hour, the movement ticks 8 times per second (hi-hat), combined with a constant force ticking for each passing second (bass drum).

The official press-release invites watch enthusiasts to visit the second floor lounge of the Grand Seiko Studio Shizukuishi where the T0 is on display:

“The rotating tourbillon and intermittent turning of the constant-force as well as the rhythmical 16th note ticking sound of the mechanisms can be thoroughly enjoyed.” -Grand Seiko

It’s nice that this can be head in-person, but Grand Seiko should make a video of the movement display in action and share the sights and sounds with the world remotely.

Accuracy:

The Grand Seiko caliber T0 has achieved accuracy of +/- .5 seconds/day under controlled testing in a lab. This is the same as the Grand Seiko caliber 9R15 Spring Drive movement.

Image Gallery:

Front side of the T0…

Grand Seiko T Zero Constant Force T0 Front

Angled view of the T0…

Grand Seiko Tzero Constant Force T0

Video:

Additional Resources:

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Gerald Wong
Gerald Wong
1 month ago

This puts the Rolex launch to shame.

Ruck Folex
Ruck Folex
1 month ago
Reply to  Gerald Wong

Rolex who?

Luke W.
Luke W.
1 month ago

I hate when watch makers make a big deal over a watch they won’t sell to the public. I was excited until I found out there’s only one and it’s not for sale.

Grailwatcher
Grailwatcher
1 month ago
Reply to  Luke W.

As if anyone could afford it if they did make it for sale. It’s an extreme feat in watchmaking. Just admire and drool.

Ruck Folex
Ruck Folex
1 month ago
Reply to  Luke W.

How is it any different than a concept car? The Rolex police will be all over the fact this is a concept and not for sale. The new Rolex watches aren’t for sale either if you have to **** a dealer to get one. They just mad this unavailable movement got more press than the new Rolexes.

Russ
Russ
1 month ago

Now this is something I’d be willing to get on a waitlist for!

SockraTEASE
SockraTEASE
1 month ago

Can we see it in a actual watch please?

Brian
Brian
1 month ago

I clicked on the IWC link you provided and read this sentence in the first paragraph on the page – IWC integrated a patented constant-force mechanism into a tourbillon. So is Seiko or IWC the first to integrate a constant-force mechanism into a tourbillon?

Val
Val
1 month ago
Reply to  Brian

After decades of being a collector I’ve learned that watch brands tend to claim something that someone else also claims, and because the other guy also claimed what someone else claimed, nothing comes of it. I’d bet IWC nor Seiko are the first, but some unknown watchmaker deep in the hills of the Jura mountains or somewhere in China.

John Parker
John Parker
1 month ago
Reply to  Brian

for someone interested in something as complicated as watch movements I find it extraordinary that you’re finding it difficult to read an article.

“the T0 is the first movement to incorporate “a fully integrated constant-force mechanism and tourbillon on the same axis.”

Chris
Chris
1 month ago

Doesn’t matter if Baselworld 2020 was cancelled because Seiko pulled out of Baselworld anyway didn’t they?

Bryce
Bryce
1 month ago

Can’t stop staring at it!

KQ
KQ
1 month ago

When do you think we’ll see the TZero in a watch?

Robin
Robin
1 month ago
Reply to  KQ

I don’t think they are putting it in a watch. It’s just a concept movement to show off their skills.

Robin
Robin
1 month ago

I don’t get the 16th note feel. If it’s 8 beats per second then isn’t it an 8 beat feel???

Jazzman
Jazzman
1 month ago
Reply to  Robin

I was just about to comment this.

Mike D.
Mike D.
1 month ago
Reply to  Robin

The movement ticks at 8bps AND the constant force beats at 8bps in tandem, so 16 bps between them. Quite an interesting mechanism.

Tony Lap
Tony Lap
1 month ago

Goes to show Seiko fans are just as bad as Rolex fans when it comes to being excited over nothing.

bob
bob
1 month ago

At a single stoke solving again at great expense two problems that had already been practically solved generations ago; 1. averaging out positional variations by rotating the balance wheel- wristwatches beat out pocket watch performance by putting the balance on the wrist where it would experience different positions as the wearer’s day in the trenches progressed while the pocket watch stayed pendant-up almost all the time. 2. isochonism reduced error with an elaborate cascade of… Read more »

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