Teaching the skull to tell the time

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Teaching the skull to tell the time - HYT
3 minutes read
HYT’s unique way of displaying the time on its watches is already complicated enough. But what happens when the round capillary takes on an even more complicated shape?

HYT created a niche in watchmaking that nobody could ever have imagined: displaying the time not by hands, nor discs, but by means of the movement of a fluid inside a tiny capillary. This capillary and the fluids that flow within it are produced at HYT’s sister company Preciflex in Neuchâtel. Our aim in this article is not to go back over the complex process of manufacturing both of these crucial components (you can refer to our Preciflex factory visit report for more details), but instead to consider the challenges posed by changing the shape of the capillary from a regular circle to an irregular skull shape. Surely this makes things a whole lot more complicated?

Turbulence in a watch?

Unusually, the answer is both yes and no, as Preciflex CEO Grégory Dourde explained to WorldTempus. “The meniscus is the border between the transparent liquid and the coloured liquid. It moves in a particular shape when we have a circular shape, like in the H1 models. But when you add angles, the shape of the meniscus changes, so there is a challenge. Imagine you are driving a car and you try to take a bend without braking. Think about the forces you would be subjected to. We have the same problem with the liquid, which has to go around bends. We did a lot of modelling to check that the angles we had in the skull could be managed at different temperatures (where the liquid would have different viscosities) without any problems. The risk was if the bend was too tight, then it would cause turbulence and there would be a risk of the liquids merging. With the skull we had to test all of this.”

A simple solution to a complex problem

Despite the challenges, the solution is almost blindingly obvious: the capillary in the skull has exactly the same length as in the other HYT models, meaning that there is the same volume of liquid and it moves at exactly the same speed (albeit slightly faster around the corners). Crucially, this also means that HYT can use the same temperature compensator as for all its other models, otherwise the entire system would have had to be completely redesigned.

The human touch – surprisingly important

You might think that this would mean that the skull-shaped capillary has to be produced to incredibly tight tolerances, but that is not the case. In reality, it is produced by a combination of machine and manual labour, as Grégory Dourde explains. “The corners are formed by hand, but the top of the skull, where it is round, is done by machines, some of which we have developed internally.” It is, however, the naked eye that has one of the most important roles in quality control for this complicated timepiece. “We have two types of tolerances,” says Mr Dourde, “those linked to the fact that the capillary is inside a watch – horological tolerances – and the human tolerance. The naked eye can immediately detect even the slightest imperfection in symmetry. So a component that may be acceptable from a purely technical point of view may not pass a visual inspection. It is even more obvious when the component it is fitted into the finished watch.”

And the future?

HYT is certainly not short of ideas. The company has filed numerous patents for its micro-mechanical innovations related to the capillary and the development of coloured fluids. More recently, it presented an innovative way of lighting up its watches in the H4 Metropolis. But the potential here is not necessarily in the illumination but in the power generation, as Grégory Dourde concludes. “We developed the light module for Metropolis and we have a patent pending for it. Since we are generating electricity we are now looking at other ways to use the electricity generated by the same means in other applications.”

 

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