moon phase

Ludwig Oechslin develops his functions from scratch and implements innovative solutions. He is driven by the challenge of displaying a function in a better way than currently available in wristwatches. He instinctively chooses the simplest approach  –  which leads to radical simplification.

When working on his moon phase watch, Oechslin sought utmost precision combined with optimal ease of manufacturing  –  which meant using as few components as possible. Here he describes his idea, his solution and his modus operandi:

Description by Ludwig Oechslin:

Task / idea

A wristwatch incorporating a moon phase indication that reflects the lunar cycle as accurately as possible.

Solution / implementation

The sun is represented by a large static dot on the dial at 12 o’clock. The moon appears in a crescent-shaped aperture, which describes an exactly computed arc around the centre of the dial. The widest point of the crescent-shaped aperture is exactly opposite the sun at the 6 o’clock position. Rotating beneath the dial is the lunar disc bearing a full moon and, opposite it, a new moon. As the disc rotates counterclockwise, the crescent shape of the aperture in the dial makes the full and new moons appear to wane as they approach the sun and wax as they move away from it; they are at their most visible at the 6 o’clock position. One complete rotation of the lunar disc therefore represents one lunar cycle with all of the moon’s phases. The lunar disc is driven by an epicyclic or planetary gear mechanism. The epicyclic wheels on the underside of the lunar disc are driven from the centre by a finger bonded directly to the hour pipe, their circumferences meshing with a recessed ring gear machined into the underside of the dial. This turns the lunar disk beneath the dial anticlockwise. The central finger engages with a wheel bearing 12 teeth, whose pinion with 14 teeth meshes with a wheel bearing 18 teeth, whose pinion with 14 teeth meshes with the fixed recessed ring gear with its 109 teeth machined into the underside of the dial. This results in a single rotation of the lunar disc in 29.5306122449 days. This is equivalent to a deviation of one day in 3478.27 years.

In our view, the wristwatch plays an integral, functional role in our lives  –  and it should be designed accordingly. Ludwig Oechslin does just that with his watches. The design of his timepieces emerges as a logical consequence of their functions, which makes it distinctive. Most of our timepieces make do without alphanumeric markings of any kind, and that includes any branding or logo.

You won’t find indications of the make and model on an ochs und junior dial, or of the watertightness, precision or country of origin. In fact, there is a logo, but it’s discreetly branded onto the back of the eco-tanned leather strap. The design of ochs und junior watches is for people who live in the here and now.

Ludwig Oechslin’s guiding principle of functional reductionism is reflected in the mechanics as well as in the appearance of his timepieces. A prototype leaves his private workshop only when he has completed the first stage  –  incorporating his latest thinking into it.

By assembling the prototypes himself, he proves that they can be produced. Small numbers of components ingeniously put together are easier to handle at a mechanical level, and thus a better solution in the long term, than one based on as many parts as possible.

Ludwig Oechslin creates and develops the mechanics and makes the initial prototypes. He then lives with them for some time, carrying them either on his wrist or in a waistcoat pocket. These prototypes don’t have an easy life. They are stressed, handled roughly and subjected to the kind of treatment that our production watches never have to endure.

Talking of production, our approach is as distinctive as our designs and unlike that of any other watch company. The technical drawings and a prototype are forwarded to Peter Cantieni. His main activity consists of machining ultra-precise titanium components for the Swiss Formula One racing team Sauber. Based in Hinwil, his experience allows him to manufacture most of the minuscule components we need for a pre-production batch of watches.

These components are then brought to master watchmaker Marion Müller. In her workshop in Kappel am Albis, she assembles the initial few watches and corrects various aspects to ensure optimal functionality and ease of assembly when the time comes for the definitive production run. The radical nature of Ludwig Oechslin’s innovative functions remains sacrosanct throughout this process. Marion Müller does not reinterpret them, nor does she attempt to make them more conventional.

After all, experience has shown that the fewer interfaces there are in a mechanical product and in its production process, the greater its reliability and the longer its service life.

Marion Müller’s feedback now helps Peter Cantieni machine the definitive components, including the two-part case, the buckle (carved out of a single block), the functional dial and the wheels. In other words, almost everything we need to create our watches, not counting the movement itself.

Marion Müller then painstakingly assembles the watch and regulates the movement, for which we use the self-winding mechanical ETA 2824-2. We rely on this dependable and highly functional workhorse for most of our watch concepts.


The watch industry usually offers two years’ guarantee against manufacturing defects. That’s also the case here at ochs und junior. The following timepieces also benefit from the ochs und junior long-term guarantee: moon phase, annual calendar, date, two time zones. These watches come with a lifelong guarantee against manufacturing defects affecting the following parts made for ochs und junior by Peter Cantieni:


moon phase (selene)

  • Case (not including the seal)
  • Buckle (not including the pin)
  • Dial
  • Moon phase function, i.e. all the planetary gearing.

The watches are functionally extremely reliable thanks to Ludwig Oechslin’s reductionist approach to components. During the periodic service interventions (or during a repair intervention if needed) we can see how the internal works are doing in terms of service life. If our appraisals indicate possible issues, we can immediately revise the parts in question for new batches of watches and, if necessary, replace them in existing watches. This guarantee also applies retrospectively to all watches in the above series that have already been bought.