Watches are a combination of craftsmanship, technology, and art. For the untrained eye, a watch would be an item created for the sole purpose of telling the time, but for horology enthusiasts, there is more than what meets the eye. One of the critical factors that influence a watch's accuracy and performance is its amplitude.
But what exactly is a watch’s amplitude? Why does it matter, and how is it measured? Let's explore these questions to better understand how this key feature will affect the accuracy and durability of your favorite timepiece.
Watchmaking Process at Tufina Laboratory.
Definition | What Is The Degree Amplitude of a Watch?
In simple terms, amplitude refers to the degree of swing in which a balance wheel moves back and forth. The balance wheel is the crucial part of a mechanical watch that bears responsibility for regulating time. You might think of it as the heartbeat of your timepiece - just like a heart pumps blood into your body to keep it going, the balance wheel keeps your watch ticking at the right time.
Normally, a healthy balance wheel will oscillate between 270° and 315°. That is a rotation that goes both ways. Having the amplitude within this range basically means that the watch gear train is running well, with sufficient power being supplied to the escapement - the actual part responsible for controlling the time of the watch.
If the amplitude falls below this range, it normally indicates underlying problems either with the power transmission or the mechanical parts of the watch. A too-low or too-high amplitude can significantly affect the performance of the timepiece. Keep in mind that such problems need to be properly addressed to ensure that your mechanical watch works as expected.
What's a Good Watch Amplitude?
A good watch is much like a well-maintained car. You don't want your engine to underperform or overheat. Similarly, you want your watch to operate within specific parameters to accurately keep time.
The optimal amplitude for mechanical watches rests between 270 and 315 degrees. That range allows the balance wheel to oscillate well and provides good consistent energy transfer through the gear train.
As with vintage watches, due to natural wear and tear throughout the years, the acceptable amplitude can be a little lower; in the range between 250-300 degrees. Even with vintage watches one can still achieve good performance within this range, however, if the amplitude is out of this range it could indicate a need for more intricate maintenance or repairs.
Depending on a given model or caliber of a watch, there could be slight variations in the amplitude. However, an amplitude above 360 degrees would indicate a full-circle rotation of the balance wheel. This can result in several problems, such asknocking or rebanking, which we are going to explain in a bit more detail later.
Why is Amplitude Important?
The watch amplitude is important in regard to accurately keeping time. The balance wheel has to oscillate in an even and steady manner for the watch to regulate time. If there is any deviation in amplitude, then the timepiece can either lose or gain time.
The amplitude of a watch is somewhat comparable to the rhythmic pulse within your body. Your body needs a stable and constant pulse. Similarly, a watch requires a normal amplitude so that it keeps time correctly. If the amplitude is too low, the watch will lose time and give imprecise results. Too high an amplitude will be as detrimental, with the possibility of mechanical failures over time.
Analogously, let’s put this into perspective by giving a simple example. Imagine you’re swinging a pendulum. Let's say you swing it lightly; the pendulum doesn't move that much. You swing it too hard, maybe it even does a full circle and breaks.
This same thing is basically what happens with the principles of the balance wheel. If the amplitude is too low, then the balance wheel does not complete its oscillation to a full enough extent, which leads to problems in time regulation. If the amplitude is too high, it may even end up breaking the movement.
Low Amplitude: What Does it Mean?
A low amplitude reading usually indicates that some problem exists inside the watch. If the amplitude falls below the acceptable deviation range, particularly below 200 degrees, it points out that the energy delivered to the escapement is not adequate.
Low amplitude is brought about by several factors:
Power Problems: This could be due to a problem with the mainspring, which stores and delivers energy to the gear train. If the mainspring is worn out, broken, or not fully wound, then it can’t give enough energy to maintain the required amplitude.
Friction: This can occur when the watch is in a vertical position with excessive friction on the balance staff or pivots. Friction slows movement down, which produces a lower amplitude, thereby negatively affecting the accuracy of the watch.
Dirty Movement: Over time, a watch will accumulate dirt and dust, and its lubricant will dry out, causing resistance to the gear train that will ultimately lower the amplitude. Regular servicing and maintenance helps with this problem.
High Amplitude: What Happens When It's Too Much?
While having a low amplitude is problematic, having an amplitude that’s too high is not any better. Whenever the amplitude exceeds the recommended range, it creates something known as "knocking" or "rebanking."
Knocking occurs when the pallet fork horns (prongs) hit the impulse pin. This creates a knocking noise but, more importantly, it can break the roller jewel and other more delicate components of the escapement. High amplitude may also place undue stress on the gear train, which can accelerate wear and tear - just like the way revving a car's engine can result in mechanical failure.
Excessive amplitude can be due to the following:
Over-winding: Although most modern watches have mechanisms that prevent over-winding, too much winding can indeed promote excessive amplitude.
Low Friction: If there is too little friction - for example when the watch was just serviced and there is over-lubrication - the balance wheel might move too well, generating a higher amplitude.
It’s important to maintain a balanced amplitude within the recommended range to avoid long-term damage to your timepiece.
Tufina Laboratory: The table shows a multitude of watchmaking tools including a timegrapher.
How to Measure Amplitude
To measure the amplitude of a watch, you would need a specialized tool called a timegrapher. The timegrapher reads the movement of the balance wheel to give an exact measure of the amplitude of the watch.
For this reading to be as accurate as possible, you first need to ensure that the watch is fully wound. The mainspring houses energy, and the amplitude changes depending on the amount of energy stored in it; thus, measuring the amplitude at a fully wound state is the best way to ensure you read the watch at peak performance.
The amplitude is also checked in different positions. The most common practice among most watchmakers, however, is testing a watch in different positions (dial-up, dial-down, and vertical positions) because the amplitudes will change with the watch's position.
For instance, if the watch is positioned face-up, amplitude usually becomes higher due to less friction on the balance staff.
Also, you need to know the correct lift angle of the watch for a perfect reading. The lift angle refers to that part of the rotation of the balance wheel during which the power is being transmitted through the escapement. Different watch calibers have different lift angles.
Conclusion: The Balance in Your Watch
In horology, success is hidden behind all those little things that count. Amplitude surely is one of those key players that keeps your watch running with pinpoint accuracy. For the collector of vintage pieces or for those who like modern mechanical watches, a little care given to amplitude could help them extend their watch's life.
If you notice some deviations in timekeeping or you hear a knocking noise coming from your timepiece, it may be worth having your watch checked for an amplitude problem. Regular servicing by a professional watchmaker can keep your timepiece in the best condition, allowing it to swing smoothly and consistently.
Now that you know more about amplitude, its function and importance, we hope you’re able to appreciate more of the intricacies of your watch and the craftsmanship involved in keeping it in a perfect state of order.
Glossary
Amplitude:The degree of swing in which the balance wheel of a mechanical watch moves back and forth. It’s measured in degrees and determines the energy and regulation of time. A healthy amplitude for most watches falls between 270° and 315°.
Balance Wheel:The part of a mechanical watch that regulates the movement of the gear train, controlling time. It oscillates back and forth, much like a pendulum, and requires consistent amplitude for accurate timekeeping.
Escapement:A mechanism in a watch that controls the release of energy from the mainspring, allowing the balance wheel to oscillate. The escapement's efficiency directly impacts the amplitude.
Knocking/Rebanking:A condition caused by excessive amplitude (above 360°), where the pallet fork's horns hit the impulse pin, leading to noise and potential damage to delicate components like the roller jewel.
Lift Angle:The portion of the balance wheel's rotation during which power is being transmitted through the escapement. The correct lift angle is crucial for an accurate amplitude reading and varies by watch caliber.
Mainspring:The component of a mechanical watch that stores energy and releases it to power the movement. A worn or faulty mainspring can lead to low amplitude, affecting the watch's accuracy.
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