Eight factors that affect the timing accuracy of mechanical watches

The accuracy of mechanical watches is influenced by many factors, the main ones being the following eight:

1.External influences:

This refers to various external factors that depend on the working environment of the watch. Common measures include shock resistance design, waterproof design, anti-magnetic design, additional protective casings, etc. Precision marine clocks often use gimbals to keep the clock level during turbulence.

2.Friction:

Friction usually has both positive and negative effects. It has a positive aspect, such as friction between the escapement wheel, the automatic watch spring, and the barrel. On the other hand, friction can cause a decrease in transmission efficiency and component wear, thereby affecting timing. Common solutions include improving lubrication conditions, selecting different lubricants according to different requirements, using jewel bearings or pads, improving gear tooth surface conditions, including using scientific conjugate tooth shapes and improving surface finish, etc. However, the gear teeth are generally unlubricated (in this case, the resistance produced by the viscosity of the lubricating oil may be higher than the friction).

3.Regulating system:

The regulating system is an economical structure that is convenient for calibration. However, both theory and practice have proven that it will affect the isochronism of the system and may produce positional errors. These timing errors have relatively high randomness and cannot be compensated or offset. The solutions include minimizing the distance between the internal and external regulating systems, but the best way is to have no regulating system and adjust the balance wheel's inertia to regulate the speed, such as Rolex's Microstella adjustment system.

4.Escapement mechanism:

The influence of the escapement mechanism mainly affects the balance wheel hairspring system during energy transfer. The balance wheel hairspring system can only maintain a fixed oscillation frequency under free oscillation. Obviously, the energy transfer process of the escapement mechanism will affect the oscillation frequency. The theory shows that when the transfer process is close to the balance point of the balance wheel, this effect will decrease. Solutions include using precision escapement mechanisms, such as the lever escapement mechanism. Its energy transfer process occurs near the balance point, the transfer angle is very small, the effect is relatively small, and its one-way transfer impact provides the balance wheel hairspring system with more free oscillation space (on this point alone, its relative error can be reduced by half!). Of course, Swiss lever escapements have good processability and are the mainstream escapement mechanism for international mechanical watches. However, in the design, the transfer angle should be minimized. Omega has launched a coaxial escapement mechanism to reduce the impact of the escapement mechanism on the timing standard. This is Dr. George Daniels' invention, but from the working principle, it is a mixture of lever escapements and pawl escapements.

5.Temperature

Mechanical watches have always been a favorite of watch enthusiasts, but even the most accurate mechanical watch cannot match the timing accuracy of a quartz watch that costs only a few tens of dollars. This is due to its own structural issues, as well as other external factors. In summary, there are eight aspects to consider.

The influence of temperature is mainly manifested in two aspects. Firstly, temperature changes can affect the working length of the balance spring and alter the inertia of the balance wheel, which can directly affect timing accuracy. Secondly, temperature changes can affect the viscosity of lubricating oil, which can impact transmission efficiency and thus affect timing. To address this issue, the following methods can be used: using a bimetal temperature-compensating balance wheel system with an open slot; using special alloy materials to make the balance spring and balance wheel, with a certain temperature compensation in the working temperature range (8°C to 38°C); and using a fast-slow hand temperature compensation. For extreme temperature conditions, such as the Omega Moonwatch, non-lubrication or solid lubrication can be used.

6.Magnetic field

The balance spring is most affected by magnetic fields, which can change its elastic modulus and cause deformation under the influence of a magnetic field, resulting in additional stress. In severe cases, the magnetic field can cause the balance spring to stick, seriously affecting timing accuracy. The solution is to use anti-magnetic materials.

7.Balance spring balance

In general, the center of gravity of a normal oscillating balance spring changes with the swing angle of the balance wheel, and under the action of gravity, it can produce position errors. The solution is to use a Breguet balance spring, which has a contracted center and a center of gravity that does not change with the swing angle, or to use a cylindrical balance spring with a Philips end curve, which is symmetrical in use. Straight balance springs have also been used. In the past, some people have used spherical balance springs, which have superior performance but poor workmanship and are rarely used in practice.

8.Balance wheel balance

The balance of the balance wheel component directly affects positional difference, and static balance of the balance wheel component is a basic requirement. If the above factors are relatively ideal and the watch's timing is relatively stable, the performance of the timing can be improved by dynamic balancing of the watch. There is a very special method: when the swing angle of the balance wheel reaches 220 degrees, various forces transmitted to the balance wheel have no effect on frequency. Some people have used a balance weight mechanism installed on the escapement wheel to control the swing angle around 220, which is also a method.