Mauron Musy nO-Ring Technology – Watertight Without Gaskets

Jul 26, 2017,22:57 PM

No gaskets? How can that work? It works really?
Well yes it does. It depends on precision machining, and doesn't deteriorate with time as gaskets do. Let's take a closer look.

For those of you that don't know Mauron Musy watches, here some pictures of the bosses watch, Christophe Musy was wearing this watch during my visit in their shop. I got it right off of his wrist for these pictures.


For more pictures of finished watches please see "> BaselWorld report here.

Eric Mauron, the second principal of Mauron Musy, owns a machne shop that does work for many big luxury brands, mainly cases, bezels and dials. About 5 years ago the two, Messieurs Mauron and Musy, decided to make a series of watches for friends and that was the start of the brand Mauron Musy. Their unique selling point is not only the nO-Ring technology, but also the polishing and finishing of their cases and dials, a result of their long experience producing parts for luxury brands.

A MM nO-Ring case starts with the circular band which is the central part of the case. The top and bottom surfaces are lapped with a planar tolerance of 0.15 micrometers (you heard correctly, that is 150 nanometers. Paired with a glass which also flat with a similar tolerance simply holding one on the other makes for a watertight seal. All the know-how is in the lapping and then how to hold the parts together without warping them.

To have a perfectly even force holding the glass in place they have developed a special circular spring . This spring is laser cut and then formed and heat treated in house.

Once the glass and holding spring are mounted the two halves of the bevel are clipped in place and already the top glass is watertight.

For the bottom glass we repeat the procedure.

The spring is compressed in place with the 4 pieces making up the outer case.

Once all is clipped together four small links are screwed in place in the 4 corners to hold all in place. These links simply hold all the parts in place, but they are not needed to maintain the water-tightness.

The next important sealing mission is that of the stem. The glasses are a static sealing problem, but the stem is dynamic. It must remain watertight although it is turned and pulled. Here again the water-tightness is guaranteed simply through extremely tight tolerances, no gaskets are needed.

The stem has 4 sections, the first has a slightly greater clearance to be able to easily insert and position the stem. The others are again lapped so that there is 150 nanometers clearance. That in itself is enough to ensure the water-tightness. Added to that MM uses a high density grease which is lodged in the grooves between the sections to give added security. What is amazing is that even with this minuscule clearance the stem is easy to turn and pull, the movement is silky.

MM uses the new Eterna caliber 39 as the engine for their watches.

We move on to the shop. As you can guess, when one is working to such small tolerances metrology tools are very important.

A CNC lathe

A 5-axis CNC milling machine

This knee mill with special tooling is used to do the precision lapping.

Only optical techniques are able to measure the flatness necessary. Using monochromatic light and a special glass the flatness is tested. These wide parallel line attest to almost perfect flatness on this case band.

Here we see the entire surface of this glass is good, not as good as the case band above, but still in tolerances.

MM have made special tooling to measure the water-tightness of their watches. Normal watchmaking testers work poorly as they depend on the deflection of the case of the watch. The spring loaded MM cases are too stiff and do not deflect. Here we see a tooling to test the water-tightness of the stem. The stem and tube are inserted.

Then the entire piece is inserted in the tester where it is tested, first at 10bar and then finally at 20 bar.

Here we see the inspection station where all the pieces are controlled before they leave the shop.

Moving on to the watchmakers bench we see a familiar sight.

Here some dials, all made in house.

And here finally the movements for the next watch deliveries, tested, dials and hands mounted and ready to go.

I hope that you have enjoyed this visit to Mauron Musy. They are a relatively new boutique maker with unmistakable year-long experience as a supplier in high level luxury watchmaking. That experience is very visible in the high quality of finishing of their cases and dials. And those capable of making a waterproof case without gaskets are few and far between.

I wish them all the best for their future and the development of their brand.

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Really nice review, thank you !

 By: Ron_W : July 27th, 2017-01:13
A new brand for me and always inspirering to learn about new takes on watch making. Also good to see the choice for Eterna as power source

Thanks for sharing.

 By: VMM : July 27th, 2017-01:51
Very interesting, it's always nice to know what's happening behind the curtains. Cheers. Vte

Very cool process!

 By: brandon1 : July 27th, 2017-06:02
Nice to see some innovation in such an unexpected area as gaskets (the absence of). Thanks! Brandon

When I first read about this watch back then, the first thought that came to mind is...

 By: skyeriding : July 27th, 2017-09:18
If there are no gaskets, what happens if the case gets deformed from a shock or knock? With gaskets, I'd imagine there is at least some allowance for them to expand and fill the gaps. Then again, I don't think the cases will deform that easily... Regards,... 

It would have to be a massive hit....

 By: DonCorson : July 27th, 2017-11:51
The entire exteriour of the case it made up of the 4 clips holding the bottom spring and the 2 besel clips holding the top spring. The central ring which makes the waterproof cavity in the middle is protected as it has no surfaces on the exterior of the w...