Cal.SXH5 | A movement controlled by gravitational inertia, not a regulator, "Philosophy of precision"

1. A regulator is a lever (pointer) used to slightly change the effective length of the hairspring attached to the balance of a mechanical watch, thereby fine-tuning the watch's advance/delay (accuracy). In English, it is called a "regulator."

What does it do? The balance wheel and hairspring of a mechanical watch are the heart of the mechanism that keeps time by reciprocating motion. If the effective length of the hairspring is short, the vibrations become faster, causing the watch to run faster. If the effective length of the hairspring is long, the vibrations become slower, causing the watch to run slower.
The regulator changes the position of the pin (regulating pin) that touches the outside of the balance spring, thereby slightly changing this effective length.

★ Common notations seen on movements
There are "+/-" and "A/R (Advance/Retard)" signs near the lever.
Moving it towards the side means it will advance, and moving it towards the - side means it will delay (how it is displayed may vary slightly depending on the manufacturer).

In recent high-end watches, an increasing number of "free-sprung" watches are being developed, which do not use a regulator to adjust the length of the balance, but instead use the inertia of the balance (variable inertia balance: adjustment weight) .
The reason is roughly that the regulator system can be easily affected by external disturbances (such as impacts and posture changes) , so a different system is chosen when stability is required.
The so-called frequency is determined by the balance between the inertia of the balance and the "stiffness" of the balance spring.

1) How the regulator works <br>The two "regulating pins" at the end of the regulator pin clamp the outer circumference of the balance spring. Move the lever to the + (advance) side → the regulating position changes and the effective length of the balance shortens → faster vibrations → advance Move the lever to the - (delay) side → the effective length lengthens → slower vibrations → delayIt's like "slightly changing the length of the strings on a stringed instrument to adjust the pitch."

2) Free-sprung, variable inertia balance (no regulator)
In this case, the inertia is changed by turning the adjustment weight (screw/mass weight) attached to the balance without adjusting the effective length of the balance spring. Adjusting the weight → changes the balance's inertia I → the vibrations become faster or slower to adjust the accuracy. The balance is allowed to "breathe freely" and is not basically clamped by a regulating pin (= there is no regulator).

Advantages of free-sprung design <br>It does not touch the whiskers, so it is easy to maintain concentricity → It is more resistant to posture changes and external disturbances
Reduced friction and impact caused by the control pin makes it easier to achieve stable rate (reproducibility).
It is easy to assemble a design that is suitable for "long-term stability" and "resistance to fluctuations after impact," which are important in high-end machines.

Disadvantages of free-sprung adjustments : Adjustment requires "turning the weight," which requires effort and skill (and can be time-consuming).
In terms of mass production and maintenance, it may be less easy to work with than the regulator type.
To achieve high accuracy, careful attention to detail is essential, including the quality of the hairs, their installation, and final adjustments.

You might be wondering which one is more luxurious.
Having a regulator does not mean it is low quality (there are plenty of excellent regulator types), and it is possible to mass-produce excellent individuals.
Free-sprung = not necessarily highly accurate (subject to adjustment and peripheral quality) and individual adjustments are required.
However, in terms of design concept, the free-sprung structure makes it easy to maximize chronometry (stability), and the regulator has a good balance of adjustability, maintainability, and cost.

2-1. Let's get straight to the point. What was done in the 2023-2024 update of the SHX5 (CZAPEK Antarctic movement)? The regulator was abandoned in favor of a free-sprung balance, and a variable inertia balance with gold adjustment weights around the four balance wheels was adopted . This requires adjustment of each individual movement, but by fine-tuning the adjustments during assembly, high precision is achieved.
By the way, although there is nothing written on the dial, it has been certified as a chronometer. It is true that writing things like chronometer or number of days of operation on the dial these days might be a little unfashionable. But it's up to you.

The element of "pinching and touching" the balance spring is reduced (it does not depend on the regulator or curved pin).
The adjustment is done on the balance side, so it works well with reducing positional differences.
However, adjustment is not "easy" and requires the skill of the watchmaker (a concept common in high-end watches).

2-2. Why micro-rotors are said to have a weak duration, and the SXH5's thinking <br>One thing that is often said about micro-rotor watches is that they tend to be less efficient at winding than full-rotors.

However, it is important to note that power reserve (design duration) and automatic winding efficiency (which varies depending on your lifestyle) are different things.
The SXH5 has a single barrel that ensures a runtime of over 60 hours, while updates to the rotor material (a ball bearing is used under the rotor instead of the usual structure to improve rotational efficiency and durability) and mechanism have been made to improve winding efficiency and extend the duration.

The movement update for the SXH5, which began in 2022, made it more than just thin and beautiful, making it practical as well.

2-3. The SXH5 achieves >60 hours at 4Hz with a single barrel. As the long power reserve approaches the end, torque drops, amplitude fluctuates, and isochronism is easily lost. However, the SXH5 employs a free-sprung mechanism that does not rely on the regulator, and a variable inertia balance with four gold inertia blocks is used to adjust the rate and poise. This is the technique used by the regulator, which aims for a "stability that is hard to lose" even for everyday use with a sporty feel.

2-3. Single-barrel movement
The SXH5 officially boasts a single barrel life of over 60 hours and a barrel torque of 8.8 Nmm .
When achieving a long power reserve with a single barrel, the design roughly involves making the mainspring longer/stronger to increase capacity.
Reduce losses (friction) in the gear train and escapement to increase efficiency.
The balance between frequency, balance inertia, and amplitude range is optimized to prevent breakdown even at the end of the movement.
Using multiple barrels to flatten the torque is a standard solution (effective for isochronism and long-power watches), but the key point of the SXH5 is that it relies on a single barrel. (Using multiple barrels to flatten the torque is also a standard solution, but it is also true that having too many barrels can cause malfunctions.)

2-4. Why inertial regulation is effective for isochronism and positional deviations <br>With a free-sprung watch, the effective length cannot be adjusted, so rate adjustment is done by the inertia of the balance (difficulty in turning). This is why adjusting by changing the inertia with a balance screw, etc. instead of a regulator, is preferred in precision design.
This is a great point for enthusiasts; while variable inertia balances are difficult to adjust, they allow for tighter mean daily rate.
It is easy to reduce posture differences (static/dynamic balance) by narrowing them. It is easy to maintain ideal breathing for the beard (= it is easy to reduce factors that disrupt the rate).

2-5 and SXH5 do it with "four gold inertia blocks"

The official SXH5 technical section states that it features a "variable-inertia balance fitted with four gold inertia blocks."
The ability to adjust inertia at four points means that (in theory) it is easy to change the average rate while maintaining symmetry, and to narrow the positional difference by combining different points (this is where the watchmaker's skill comes into play).

2-5. The influence of free spring on "isochronism (torque fluctuation)" <br>The flow of torque decreasing → amplitude decreasing → rate fluctuation, which mitigates the "rate fluctuation" when the amplitude fluctuates, is difficult to avoid.
However, with free sprung + variable inertia, the adjustment points are concentrated on the balance wheel side, reducing interference factors (curve pins), which makes it easier to "clean up" the behavior during amplitude fluctuations.
Flattening the torque curve itself basically involves working in areas such as multiple barrels, constant force mechanisms (such as fusee chains), optimising the design of the mainspring/barrel/going train, reducing friction and maximising escapement efficiency (free-sprung is the "philosophy of the regulator").
That's why, in the case of the SXH5, we have thoroughly refined the gear train efficiency and regulator design within the conditions of a single barrel of 60h, barrel torque of 8.8 Nmm, and 4Hz.

3-1. The mechanical movements of Swiss watches are constantly evolving. But what about Japan?

Major Japanese manufacturers are also now using in-house movements.

Seiko: Grand Seiko (kodou) is equipped with a constant force and tourbillon, which is a huge challenge. Also, the familiar Spring Drive from Grand Seiko is a hybrid type that is controlled by a mainspring, quartz crystal, and IC.

Orient Orient Star: Orient Star F8A62 ( in-house mechanical movement )

・Citizen THE CITIZEN: Caliber 0200/0210 (in-house mechanical movement)

Most watches made by independent Japanese watchmakers use generic movements. When repairing, the internal components are inevitably visible. However, generic movements are not so bad if you consider that the parts remain semi-permanently. In fact, they are easier to repair and tend to last longer.
There are issues of cost and the experimental nature of the idea, but there may be some interesting attempts in the future.
Of course, some independent Japanese watchmakers are also experimenting with creating their own base movements (NAOYA HIDA & Co. Cal. 3019SS: Base movement Valjoux 7750, Otsuka Lotec: Base movement Unitas 6498).
There are no examples of a movement being designed from scratch by a small, independent watch workshop, but we look forward to seeing what happens in the future.

CONTÉVANOU has several CZAPEK watches on display. You can compare the depth of the dial, the fit of the case, the texture of the bracelet/strap, and other aspects that are difficult to judge from images in the store. If there is a model you are interested in, please feel free to contact us to check availability.

Points to check at the store

What is difficult to convey online is the "depth" of the rear scale and the presence of the balance wheel.
The scenery of the gear train created by the off-center micro-rotor, the shadows of the bridge, and the angle change of the finish, as well as the adjustment weight of the balance wheel, show a "structure for precision"
Then, after seeing the photos of how the case fits and balances on the wrist, I was attracted to the watch and decided to try it in person. The CZAPEK is exactly that type of watch.

Authorized Watch & Jewelry Dealer CONTÉVANOU
Nishi-sando Terrace E1, 28-7 Yoyogi 4-chome, Shibuya-ku, Tokyo 151-0053
TEL 03-3299-8008