My Top 5 Favorite Watches with Helical Hairsprings

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Balance spring: the devilishly complex yet surprisingly simple heart of the mechanical watch.

Hairsprings are notoriously difficult parts to manufacture, particularly reliably, so only a handful of companies can manufacture them, and one of them (Nivarox, owned by the Swatch Group) still accounts for every product made. It makes up the (slowly shrinking) large part of the hairspring. Every year.

Over the past 20 years, a few independent brands have begun producing watches in relatively small quantities in-house, often by hand, but most are still industrially produced in large quantities.

Interestingly, nearly all balance springs made follow roughly the same form factor, meaning that the balance assemblies are closely related in design and function. But for some manufacturers, the choice to go a little unusual for a particularly special watch can lead engineers to step up the ladder into the even more complex world of spiral balance springs.

Montblanc Tourbillon’s enchanting cylindrical balance spring and elegant bridge Cylindrical Geosphere Vasco da Gama

Spiral balance springs, also known as cylindrical balance springs, are made in a similar process to making a basic balance spring by hand, with one major difference. To make a basic hairspring, insert thin spring wires into a mandrel (usually four at a time, at 90 degree angles to each other) and carefully wrap them around a flat jig so that the four wires Wrap it completely.

The entire jig is then heat treated and tempered to achieve the appropriate material properties for the hairspring and set the metal to the proper shape.

The spring is then separated into individual springs, all of which are perfectly helical with gaps the width of the thickness of the other three hairsprings, providing consistent tolerances throughout the helix. .

This handy trick is not possible with a spiral hairspring because the diameter is constant along its length, but the spacing between the wires is not equal to a multiple of the wire thickness. This requires the use of a custom-formed mandrel so that only one spiral balance spring can be formed at a time.


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