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Chapter 2 - Preamble, a Mu:n in-house caliber

Updated: Apr 9

Dear community,

We are pleased to share with you the progress made during the first quarter, as well as the recent developments and prospects of the Ariane project.

Today, this chapter concludes after an intense period of reflection, enriching encounters, and in-depth technical studies. We're introducing a new video format with Victor, founder of the Mu:n projects, who will cover all the latest news and next steps.

Centered around three chapters, the collaborative Ariane project aims to create a new moon phase watch. With over 3,900 engaged participants, your enthusiasm has been a significant source of inspiration and motivation for the team. A big thank you for your active participation!

Today, the first chapter concludes after an intense period of reflection, meetings and technical studies. You can find the detailed results in the dedicated article: Chapter 1 results.

In search of a new caliber

The first quarter was an opportunity to reconsider sketch No. 17, and even more so the choice of calibre SW288-1a. This choice had been guided last December by three factors in particular: production costs, our supply capacity and the logistical management of our stocks.

At the start of this year, we wanted to open up the field of possibilities, to be more in line with your numerous written feedbacks - and a refined analysis of the results. A new wave of discussions, meetings and feasibility studies has thus been underway for three months, to explore new possibilities for the ARIANE edition.

What's more, we really wanted to mark this edition with a strong innovation, a real novelty on the market. This quest is at the heart of Mu:n projects, and the sketches proposed in the first chapter lacked a touch of daring.

In response, we decided to initiate the development of a new Mu:n modular caliber for the ARIANE edition. This initiative marks a crucial step for the future of Mu:n creation and projects.

Before going into detail about the reasons for this decision, it is essential to understand the current market context.

An eye on the market

Excluding second-hand calibers, and within a realistic price range (under 400-500 Swiss francs) the market currently offers three main calibers, considered ready to use - i.e. available to order and in series production.

Caliber SW288 - 1a

SELLITA Manufactures

Sellita SW288


Central moon phase (59 teeth)

Date window (at 3 / 6 o'clock)


40 hours power reserve

4 Hz (28,800 A/H)

Quick correction for date/moon

Caliber SW382

SELLITA Manufactures

Sellita SW382


Moonphase at 6 o'clock (59 teeth)

Day of the month by hand


56 hours power reserve

4 Hz (28,800 A/H)

Quick correction for date/moon

Caliber C105

SOPROD Manufactures

Soprod C105


Moon phase at 9 o'clock (135 teeth)

Date window (at 3 o'clock)

Small second (at 6 o'clock)


42 hours power reserve

4 Hz (28,800 A/H)

Quick correction for date/moon

Faced with the impossibility of freeing ourselves from "standardized" designs, we initiated meetings with various specialized workshops. The aim? To develop a new caliber. We hoped to find in this decision a new space for creativity and innovation, in line with our wishes and your feedback.

A pivotal meeting, the BCP SA workshop

A decisive turning point in this adventure was our collaboration with O. Mory, a renowned watch engineer. He agreed to take on this technical challenge with us, consisting of creating a Mu:n-specific modular movement capable of accommodating all the envisioned complications. This development marks a significant step for ARIANE and for all Mu:n projects.

You can meet Olivier Mory in a video detailing his work, produced by Julien from the channel 10ATM.

An Mu:n caliber

Technically, the new Mu:n caliber will be based on Sellita's SW500 and La Joux-Perret's L100 calibers. These calibers were chosen for their native chronograph and date functions. Both offer a power reserve of around 60 hours and a frequency of 4Hz.

It should be noted that initial studies have revealed the need to maintain a reduced thickness (8 mm) - a sine qua non for the caliber's development. We therefore expect an edition with a case thickness of less than 12-13 mm.

In addition to a chronometer featuring 60-second (A), 30-minute (B), and 12-hour (D) indicators, with a small second (C), the following are under study:

  • 24-hour hand (E)

  • Day indicator by hand (F)

  • Day/month indicator (at 12 o'clock)

  • Perpetual moon phase (at 6 o'clock);

Mu:n caliber

This development opens up new perspectives for future Mu:n collections, offering unprecedented design freedom and guaranteeing technical and aesthetic exclusivity. In addition, the caliber's modular design allows complications to be displayed (or not) according to the design chosen. It would thus provide a unique design base, to be varied according to future editions of ARIANE. Different versions can be imagined, from the most complex to the most refined.

Financing for this modular movement, costing around CHF 15,000, will come from the funds raised by the Artemis project, which is widely supported by the community.

For the workshop price, the addition of such a module amounts to around CHF 300, on a movement that itself costs CHF 400. The production cost of the Ariane model should therefore be in the region of CHF 1,000. We'll come back to the cost structure in more detail in a future article.

Next steps

The ARIANE project has therefore been put on hold for the next few months, which will be devoted to various phases of research and study relating to the development of this new Mu:n caliber. This period of reflection will lead to a new chapter at the end of the summer, focusing on the design of the dial around this in-house movement. The ARIANE project will unfold throughout the year, with an anticipated launch in December 2024.

A first sketch of the next steps is proposed below. We understand that time may seem long, but it's technical and human time at work. Some would say a lunar time?



Chapter I


Watch creator


Moon configurator



First sketches


Technical studies


Mu:n caliber


End of the first chapter


Technical studies


Chapter II

Regarding sketch No. 17, the work done so far is far from being shelved. On the contrary, this design, which has generated significant interest, will be reworked and refined in collaboration with you for a future edition planned for 2025.

In the meantime, we have some very nice surprises with the arrival of a new collection in a few weeks. We will address this in an upcoming article..


Creation is a dynamic adventure that evolves with challenges and opportunities. With ARIANE, and more broadly with the Mu:n projects, we are now embarking on a new path that illustrates our vision of creation: a story that is built and woven over time.

This creative journey is at the heart of our commitment, where innovation and creativity meet and confront technical constraints. We are delighted to continue this collaborative approach with you, and we warmly thank you for your enthusiasm and active participation in this horological journey.

See you soon,

Victor and Thibault


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