The watch precision has developed tremendously in time

Since the establishment of fixed hours, clockmakers have strived to render the watches as precise as they could, through different, ingenious devices.

The Salisbury Cathedral Clock, circa 1385

We know from experience that tests conducted on the oldest surviving mechanical clock in the world, the faceless clock of the Cathedral of Salisbury, dating approximately to 1385, have discovered that the watch precision that this timepiece obtained was remarkable, within two minutes per day.

Such a performance – which was indeed very good for the time – would be replicated by watches only much later, and thanks to lots of development by figures like Galileo and Huygens.

Indeed, around 1650, another scientist called Robert Hooke theorized something that would be important for watchmaking: the theory of harmonic oscillations, which would be important for two key elements of the watch: the mainspring and the balance wheel. And as both of them use a spring in their operation, the smartest of my readers have understood about what we are talking about.

Read also Why Rafael Nadal’s watch is so expensive?

The application of Hooke’s Law

In short, a spring impart to a weight suspended on them a movement that is “harmonic” – it follows a constant sinusoidal oscillation path, if released.

In the ideal condition of no attrition, it would continue to oscillate like this forever.

But even if it doesn’t, if we continue to apply constant force to it making it move in such a way, the oscillation will continue regularly.

And this is the main principle we apply to watches.

The regulatory device of a watch works like this. That is, it is based around a harmonic oscillator of some kind.

The first harmonic oscillators used in watches were the balance springs. They are the tiny spiralling springs that lie on top of balance wheels and make them oscillate back and forth following a harmonic oscillation.

The increase in watch precision: electromechanical watches

In the quest for better precision, watchmakers discovered that a tuning fork emits  a fixed vibration that is based on harmonic oscillation as well. The diapason was miniaturized and used as a regulating device in watches such as the Bulova Accutron.

Bulova Accutron Spaceview. Tuning fork on the center/top.

The evolutions of electromechanical watches – which debuted in the 1960s – have brought us the quartz-based system, which works on a different system based on a similar concept.

The oscillator in a quartz watch

In a quartz-based watch – the first one was the Seiko Astron, which was launched in 1970, we find an oscillator composed by a quartz crystal that is cut in a small tuning fork shape on a particular crystal plane.

When subject to a current, this crystals vibrates at a specific frequency – which is subject to the electrical current applied to it. This frequency was originally 32,768 Hz (some of the latest quartz movements vibrate at higher frequencies). insuring a very high watch precision.

Today, we are exploring other solutions to create a harmonic oscillator. The next frontier in this research will be the use of silicon elements. Several promising calibers have been manufactured, like the Zenith Defy. However, the industry is still using either mechanical-based regulating elements based on balance wheels or quartz-based systems (and their evolutions like the Seiko Kinetic and the Seiko Spring Drive.

A swan-neck regulator on this mechanical watch movement

How do you regulate these systems?

Obviously, when a watch comes out the factory it is not precise at all. It must be regulated to achieve a good precision. And watchmakers have developed ways to regulate the different movements so they perform at the best of their possibility.

The mechanical watches use an ingenious regulator placed obeve the balance wheel bridge (known as a balance wheel cock) – it is a regulator that can be turned to adjust the dimension of the hairspring. Diffenet dimensions would lend the balance wheel to beat slower or quicker.

While the regular watches had a lever, more precise ones have micrometric adjustments regulated by a screw. Some modern watches use different systems to regulate, such as counterweights placed on the balance wheel itself.

In a quartz-based watch, regulation is not possible. That is, it is already built in.

You can see this black blob under the orange arrow? It covers a small microchip which controls the operations of the quartz movement. This means that the quartz resonator (the grey cylinder you see on the left) has a built in correction that intervenes if it feels that the vibration rate of the watch is out of the range.
In the first quartz movements, watchmakers could intervene to regulate the watch through a tiny screw, but as time passed, the circuits were streamlined and simplified, and the microchip was inserted to resolve the issue from the beginning.

You can find much more about horology and its fascinating history in The Watch Manual. It is a thorough e-book that explains all the basics about watchmaking and its protagonists.

To download a FREE 8-chapter extract from The Watch Manual
please CLICK HERE

0 replies

Leave a Reply

Want to join the discussion?
Feel free to contribute!

Leave a Reply

Your email address will not be published. Required fields are marked *