The standards for what makes a "good watch" vary from person to person. However, some easily identifiable points include the finish and construction. "How to Appraise a Good Watch" explains how to "distinguish a good watch" from that perspective, but this time we'll take a slightly different approach and focus on the "regulation mechanism." We'll explore how to choose a good watch by looking at the different types of mechanisms, the advantages and disadvantages each brings to a watch, and how to distinguish between each mechanism.
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Interview and text by Masayuki Hirota (Chronos-Japan)
[Article published in the July 2020 issue of Kronos Japan]
A good watch from the perspective of its regulator mechanism
Caliber PF110 uses a swan-neck regulator, known as a fine-adjustment regulator. Moving the regulator changes the length of the balance spring, just like other regulators. However, because the regulator is moved by turning a screw and held down by a "swan's neck" shaped spring, precise positioning of the regulator is possible. However, today it is primarily a decorative element. As befits a high-end watch, the balance spring is a "kidney-shaped" one, with both the winding hairspring and the balance spring stud movable.
How do you adjust the speed of a watch, that is, whether it loses or gains? There are only two ways to do this. One is to change the effective length of the balance spring. The other is to change the inertia of the balance wheel. The former is the regulator used in many watches, and the latter is the free-sprung mechanism preferred in the latest in-house movements. Each mechanism has its advantages and disadvantages.
Advantages and disadvantages of regulators
Chopard's Caliber LUC 98.01-L has the same details as the Caliber PF110. However, in consideration of robustness and ease of maintenance, the regulator is adjusted by turning an eccentric screw (the middle of three screws) built into the spring retainer on the swan neck. When the screw is turned, a blade pops out and pushes the regulator. Although it is expensive to manufacture, it is a conscientious design typical of Chopard. It overcomes the weak point of being difficult to adjust when the watch is in the case.
Many mechanical watches use a regulator. This mechanism uses two balance pins to change the length of the balance spring. If the pin is moved closer to the end of the balance spring (the balance stud), the effective length of the balance spring increases, causing the balance to lose pace. Conversely, if it is moved closer to the center, the effective length decreases, causing the balance to gain pace. The wide adjustment range and ease of adjustment are the reasons why regulators have become widespread and have been used for so many years. However, as they are often called a "necessary evil," regulators also have many disadvantages. The balance pins suppress the free vibration of the balance spring, making it difficult to stabilize isochronism. Furthermore, if the watch is subjected to shock, the regulator will move, easily changing its accuracy. Furthermore, because the balance pins come into contact with the balance spring, long-term isochronism also deteriorates.
A free-sprung balance that eliminates the disadvantages of a regulator
Rather than changing the length of the balance spring, the free-sprung balance adjusts the speed by moving the mass slots attached to the balance wheel. Chopard's Variner balance wheel has two pairs of mass slots attached to the rim of the balance wheel, significantly reducing air resistance, which is said to account for two-thirds of the resistance acting on the balance wheel. In a touch typical of Chopard, the balance wheel has a notch in the bridge to make it easier to turn the mass slots.
An automatic chronograph with flyback, vertical clutch, and free-sprung (Variner balance). Since its release in 2007, it has undergone minor improvements and evolved into its third generation. The current model is water resistant to 100m. Automatic winding (Cal. LUC03.03-L). 45 jewels. 28,800 vph. Power reserve of approximately 60 hours. Titanite case (42mm diameter). Water resistant to 100m. Limited to 100 pieces worldwide. (Inquiries) Chopard Japan Press Tel. 03-5524-8922
The free-sprung balance wheel overcomes these drawbacks. Currently, the majority of models feature free-sprung balance wheels, including Patek Philippe, Rolex, Breguet, H. Moser & Cie., Audemars Piguet, A. Lange & Söhne, Panerai, Omega, IWC, and Jaeger-LeCoultre.
Like the latest movements, the Cal. 4302 uses a Gyromax balance wheel instead of a regulator needle for its regulator adjustment mechanism. The previous Cal. 3120 had adjustment mass slots that protruded from the balance wheel, but in this model, they are placed at the same height as the balance wheel, presumably to reduce air resistance. There are three pairs of mass slots in total. The balance wheel's moment of inertia is 12.5 mg/cm2, nearly three times that of the Cal. 3120, so portable accuracy should be excellent.
Patek Philippe was the first to use a free-sprung balance without a regulator in a mass-produced wristwatch movement. The small-diameter 215 PS also features their signature Gyromax balance. Some say that small-diameter movements are not suited to free-sprung balances, but one of the reasons for their excellent portable accuracy is clearly due to the free-sprung balance. Although the basic design is old, it is an extremely excellent movement.
A free-sprung balance is an adjustment mechanism that adjusts speed without changing the length of the balance spring. Specifically, the inertia of the balance wheel is changed by changing the phase and position of the balance weights (mass slots and balance screws), thereby adjusting speed. Because the balance pins do not interfere with the free vibration of the balance spring, the theoretical isochronism is extremely high. Furthermore, even when subjected to a strong impact, the balance pins and balance spring do not become entangled. The reason why various manufacturers are now able to adopt silicon balance springs is due to the widespread use of free-sprung balances, which do not clamp the balance spring with the balance pins.
With the exception of a few movements, A. Lange & Söhne currently uses a free-sprung balance without a regulator. This is also the case with the Cal. L093.1 shown in the photo. The part that looks like a swan-neck regulator is a mechanism for adjusting the position of the movable balance pin. As proof of this, there is no balance pin. The reason they adopted this very ostentatious and confusing structure is because the swan-neck regulator has become a tradition at A. Lange & Söhne.
Of course, there are also disadvantages. One is that the adjustment range of a free-sprung balance is small compared to the wide adjustment range of the regulator. For this reason, free-sprung balances were previously only available on precision-made, high-end watches. Also, theoretically, the benefits are less apparent if the balance wheel is small. The famous Giulio Papi once said, "A free-sprung balance is meaningless unless the balance wheel's moment of inertia is at least 10 mg/cm."
The new J12, announced in 2019, uses the Cal. 12.1 with a free-sprung balance. Because it lacks a regulator, it's resistant to shocks and less prone to tangling. It's ideal for a sporty watch. The balance bridge is also double-supported for increased rigidity. Precision is adjusted not by a mass slot, but by a counterscrew attached to the side of the balance wheel. However, by recessing the balance wheel, air resistance is reduced.
The pinnacle of Japanese-made movements is the Cal. 9SA5. It incorporates a free-sprung balance that is adjusted with a balance screw, a rotating balance spring stud that allows for adjustment of the outer end of the balance spring, a winding balance spring with a completely new outer end curve, and a height-adjustable, double-supported balance cock, all of which are designed to improve precision. Again, to reduce air resistance, the balance screw is embedded in the rim of the balance wheel.
Excellent regulator
There are also some excellent regulators. These are called fine regulators, and good examples are the swan-neck and triovis types, which allow for fine adjustments. These allow for precise adjustment of the regulator using a screw. Many fine regulators also have closely spaced balance rods, which gives them excellent isochronism. Triovis is a registered trademark, and similar regulators are called triovis types. Nowadays, swan-neck regulators are mostly decorative, and those that are retrofitted to etachrons, etc., described below, have no value other than aesthetic appeal.
One of the most well-known fine-adjustment regulators is the Triovis. By turning the screw inserted into the balance stud, the regulator can be moved left and right. Like the swan-neck regulator, it allows for fine adjustments. As the regulator is moved by a rack gear that meshes with the screw, it is relatively resistant to shocks. Currently, in addition to Nomos, it is used by Chopard, IWC, and others. "Triovis" is a registered trademark of Meisier, a subsidiary of the Swatch Group.
The etachron, used in many mass-produced ébauches, is classified as a semi-fine regulator. This is a well-known regulator, but it is vulnerable to impacts due to the large spacing between the balance rods, the weight of the balance rod studs that secure the balance rods, and the weight of the integrally molded balance rods. However, the etachron can be twisted to freely change the spacing between the balance rods and the balance spring (this allows for the swing angle to be changed), making it easier to stabilize accuracy even if the balance swing angle decreases. A skilled watchmaker would not have difficulty achieving chronometer-level accuracy in an ETA ébauche. Breitling, which made extensive use of this technique after 2000, has improved the performance of its movements.
The ETA7750 uses ETA's standard regulator, the Etachron. This is a semi-fine regulator that allows for fine adjustments. The yellow part at the tip of the regulator is a balance rod that is integrally molded with the fixed part. By twisting it left and right, the balance can be adjusted, just like the Cal. 9S27. The outer end of the balance spring is a different color because it has been annealed to reduce its hardness. Although it is currently unknown, this was once a major feature of Nivarox balance springs.
The successor to the masterpiece, the 203.ARKTIS. It remains water resistant to 30 bar and temperature resistant from -45°C to +80°C, but it now features the D3 system, which allows the chronograph to be used underwater, and a special coupling makes the rotating bezel less likely to come off. It's equipped with the "top" grade ETA7750. Automatic (Cal. ETA7750). 25 jewels. 28,800 vph. Power reserve of approximately 46 hours. Stainless steel case (43mm diameter). Water resistant to 30 bar. (Inquiries) Hotta Tel. 03-6226-4715
Breitling has improved the precision of its movements by refining its control techniques. The techniques developed for the Cal. 13, an improved version of the ETA7750, were also applied to the Cal. 01, the company's own movement. The watch is equipped with an etachron-style regulator. Like an etachron, it allows for easy control adjustment. The base supporting the regulator is extremely strong, preventing it from shifting even when subjected to strong impacts.
The regulators on the Grand Seiko 9S6 and 9S2 series are also capable of adjusting the movement, just like the Etachron. However, the regulators are closer together and the mounting torque is stronger, making them more resistant to shocks.
The small-diameter Cal. 9S27 is equipped with a semi-fine regulator that allows for fine adjustments to improve accuracy. The T-shaped part is the part that allows for adjustment of the balance (the distance between the balance rod and the balance spring). The balance can be adjusted by turning the round eccentric screw on the left side. In theory, this makes it easier to maintain accuracy even if the amplitude decreases. A detail that was popular in the movements made at the former Daini Seikosha Kameido factory has also been adopted for the latest women's movement.
This is Grand Seiko's women's automatic movement, which has been highly praised in this magazine. This watch is equipped with the mass-produced version. It features a highly efficient mainspring winding mechanism, good magnetic resistance, and a long power reserve. Automatic winding (Cal. 9S27). 35 jewels. 28,800 vph. Power reserve of approximately 50 hours. 18KRG case (diameter 28.7mm, thickness 10.9mm). Water resistant to 10 bar. (Inquiries) Seiko Watch Customer Service Tel. 0120-061-012
Grand Seiko's high precision is due not only to the basic performance of the movement, but also to the regulator, which allows for adjustment of the movement angle. The photo shows the regulator of the hand-wound Cal. 9S63. The balance rod is fixed to a rice paddle-shaped part, and the movement can be adjusted by twisting it left and right. The Cal. 9S27 is an improved version of this regulator. The movement of the regulator itself is adjusted by turning the left-hand eccentric screw, which has a scale engraved on the outer periphery.
How to identify the regulator mechanism
A comparison of difficult-to-distinguish speed regulators using conceptual diagrams.
❶ is a standard regulator. By moving the needle-shaped part left and right, the tip with two hairpins embedded in it (the regulator in the narrow sense) moves, changing the effective length of the balance spring. The part closer to the hairpin is delayed, and the further away it is, the more advanced it is. Note that with Etachron and Seiko types, the balance can be adjusted by turning the part where the hairpins are attached.
❷ is a free-sprung balance. Instead of a regulator, the phase is changed by turning a weight (mass slot) on the balance to adjust accuracy. When the weight points outward, the inertia of the balance increases, causing it to tend to lag. When the weight points inward, the inertia decreases, causing it to tend to lag. This is an excellent mechanism, but it is only used by a few manufacturers.
❸ Classic balance screw. Nowadays, the majority of balance screws are merely decorative, but like free-sprung watches, some allow you to adjust the speed by changing the inertia of the balance wheel. Shifting the balance screw (mean time screw) outward increases the inertia of the balance, making it tend to run slower. Shifting it inward reduces the inertia, making it tend to run faster. High-end watches of the past used a fine-adjustment regulator in combination with a balance screw to achieve excellent accuracy.
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