moon phase

How is Oechslin’s moon phase function implemented?

An epicyclic gear train driven by a central finger bonded directly to the hour pipe turns the lunar disk beneath the dial counter-clockwise. 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 (annotated diagram).

What is the benefit of a highly precise moon phase calculation?

The average time between two identical moon phases is 29.530589 days. Most moon phase watches approximate a lunation as 29.5 days, which leads their calculation to be off by 1 day after 2 years. The closer your moon phase calculation comes to the average lunation of 29.530589 days, the “flatter” the difference between your prediction and the actual moon phase. The ochs und junior moon phase calculates the lunation as 29.5306122449 days. As a result, it will predict the moon phase correctly for 3,478.27 years before it is off by 1 day. This means that you only have to set your moon phase one time, and you can trust that its prediction is precise.

Watches and astronomy by Ludwig Oechslin.

Ludwig Oechslin’s moon phase watch displays the moon phase, date, and time. It features a unique moon phase function executed as a 5 part epicyclic gear system that will take 3,478.27 years before its calculation will be off by 1 day. The analogue, spiral date with dots is better readable than a digital display from the same distance, and brings the date in visual harmony with the clockwise display of hours and minutes.

Your moon phase watch

ochs und junior manufactures about 50 moon phase watches per year. You can select your moon phase watch from models designed by ochs und junior in our online shop. Or you can design your moon phase watch using our online customizer. With pleasure, we will guide you to your perfect moon phase watch on the phone, over email, or in person.

Dimensions

42mm x 11mm (incl. crystal)
39mm x 11mm
36mm x 11mm
Print 1:1 (PDF)

Weight

42mm titanium: 70g (incl. sturgeon leather strap and buckle)
39mm titanium: 62g
36mm titanium: 53g

42mm sterling silver 925: 109g
39mm sterling silver 925: 101g
36mm sterling silver 925: 93g

Water resistance

100m in titanium, 100m in sterling silver 925. Both models are fit for almost any situation in daily life.

Case

2-part case designed by Ludwig Oechslin. Available in grade 5 titanium or sterling silver 925; additional materials upon request. Visible machining marks. ochs und junior watches require no movement ring due to the extremely small manufacturing tolerances on the case. Available exclusively with a solid case back.

Moon phase function

5-part epicyclic gear system designed by Ludwig Oechslin. The calculation is precise for 3,478.27 years before it is off by one day.

Date function

30+1 hole date spiral with 5 minute markers that serve as reference points designed by Ludwig Oechslin.

Base movement

ETA 2824-2 with 38 hours of power reserve. Manufacturer: ETA SA / Grenchen / Switzerland.

Crown

Screw-down crown designed by Ludwig Oechslin (39mm and 42mm). Manufacturable on the right or left side of the case. Available in grade 5 titanium or sterling silver 925; other materials upon request. In 36mm the crown is not screw-down, however all sizes have the same water resistance rating. Manufacturer: Pibor SA / Glovelier / Switzerland.

Buckle

Leather strap: Designed by Ludwig Oechslin for 22mm watch straps with no loops. Visible machining marks. Grade 5 titanium or sterling silver 925; additional materials upon request. The design of the buckle differs slightly for a 42mm and a 39mm case and matches the lugs.

Rubber strap: Classic buckle, designed by Ludwig Oechslin. Visible machining marks. Grade 5 titanium or sterling silver 925; additional materials upon request. The design of the buckle differs slightly for a 42mm and a 39mm case and matches the lugs.

Watch straps

We offer over 80 possibilities, which you can explore in our straps pages: sturgeon, leather, suede, rubber.

Crystal

The sapphire crystals are manufactured by Stettler in Lyss / Switzerland. Both sides are treated with anti-reflective coating by Econorm in St-Imier / Switzerland.

Reading the time in low-light or dark conditions

For optimal readability our watches are coated in Super-LumiNova X1, manufactured by RC TRITEC in Teufen / Switzerland. Super-LumiNova is always applied in conjunction with a color pigment. All Pantone colors are available, but the brighter the color, the better the luminosity. Super-LumiNova shines green (the option used by ochs und junior) or blue, on special request. The Super-LumiNova coating is applied by hand by ochs und junior, or for dials with a color application by Cador in Eimeldingen / Germany and by Monyco in La Chaux-de-Fonds / Switzerland.

Swiss made

The ochs und junior moon phase watch is entirely manufactured in Switzerland. Each watch is hand-assembled and regulated at the ochs und junior workshop in La Chaux-de-Fonds.

Lifetime warranty

A lifetime warranty covers all parts invented by Ludwig Oechslin, and the entire watch is covered by a 2 year guarantee. ochs und junior’s small scale and direct sales model allow it to offer uniquely fast and competent service.

Designed by ochs und junior

Watches in the moon phase shop are designed by ochs und junior. Individually manufactured, they have the potential to become classics.

Custom-made

Ludwig Oechslin’s rigorously simple designs, the fact that we individually manufacture our parts, and the direct contact we have with our clients enable us to offer the highest possible degree of customization. The customizer shows many possibilities.