Girard Perregaux

PeterCDE
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GP 2008 - A very short introduction of GP´s new free-sprung escapement MICROVAR

Dear enthusiasts,

it is with special pleasure to introduce a great new development by GIRARD-PERREGAUX:

MICROVAR
GP´s propietory free-sprung balance

For most of GP´s history, starting in 1860´s up to now, the brand spend serious efforts on precision watchmaking.
There are numerous examples to tell this part of the brand´s heritage; be it the award-winning Three Gold Bridges or the famous fast-beat Observatory Chronometers, all of them and a number of GP patented construction aimed at improving accuracy for a portable watch.

The timing result of a wrist watch is influenced by the escapement to a large degree.
This micro-system includes the balance wheel, the escapement of anchor and escape wheel, the hairspring and the regulation organ. It needs to be constructed and executed very finely, because slightest tolerances in any component will affect the timing of the complete watch afterwards.
A specifically challenging task is to adjust and regulate the movement. There are many different ways and far too many scientific research volumes written on this matter, but in a highly simplified view this is mainly done by influencing the beat rate (the "tick tack"). The beating of a watch  escapement is mainly influenced by the length of the hairspring and the combination of the balance wheel and the hairspring, which describes the two basic methods to adjust and time the "tick tack" of a timepiece.
Conventional watches make use of a regulation organ which interacts with the hairspring; a mechanism is capable to shorten/widen the effective length by means of a "finger" touching the hairspring, which is the approach in use by far most of the timepieces around.
The other method, which is more difficult in terms of manufacturing, is the so-called "free-sprung" escapement. Here the hairspring is allowed to "breathe", in that it winds and unwinds without being affected by the regulation organ. The proper "tick tack" is achieved only by adding/taking weight from the balance, which is carefully choosen to match the natural frequency of the hairspring. And such requires an adjustable balance, which can be adjusted to perfectly match the hairspring and the time it needs to wind up or unwind.

Of these two, the classic regulation organ already did proof itself in GP manufacture-made watches for more than a decade. GP movements are known to be accurate and sturdy, therefore one may suspect not much room for improvement is left.

But it wouldn´t be GP, the creative brand it is, if not searching for other ways.
And that´s something directly connected to GP´s history as well, as a side note from a more anecdotal perspective may tell:
Back in 1965, Girard-Perregaux presented the world´s first fast-beat escapements using a frequency of 36.000 A/h, while conventional watches offered a beat rate of 18.000 to 21.600 A/h.
The increase in beat rate resulted in an accuracy unheard of before, at least for watches intended to be sold and worn in daily wear instead of being unique pieces of Chronometric Competitions.
It may not be a surprise, knowing the very competitive watch industry ever since, to learn one of the largest brands world-wide didn´t hesitate and carefully examined one of the very first fast-beat watches by GP available, then the manual-wind caliber variant. After weeks of testing, measuring, exploring, including complete disassembly of the piece up to metallurgic research work, the result was very simple. "It´s better than anything we´re doing" (and that´s quite a word for a brand well known for high-precision watches too). The engineers and watchmakers came up with only two possible improvements for the fast-beat escapement ; one was an automatic winding unit, which already was in the making at Girard-Perregaux and debuted in the Chronometer HF models in 1966.
The other one was a free-sprung escapement, so that no regulation organ would interact with the hairspring and disturb it´s tremendously fast and precise motion.

Fast forward to today´s movement, the beat rate today is almost universally set to 28.800 A/h for most watches.
This beat rate did proof itself to be the best compromise between slow beat rates (which used to be not as accurate, but safe service intervals) and fast beat rates (which were more accurate, but demanding in terms of lubrication and power supply). This result is influenced by GP´s (and others to follow with higher beat rate escapements) work then.

But a free-sprung escapement still had to be designed at GP, which is no little effort.
It took the brand years of research to find the best solution for the manufacture-made movements, which needs to include many variables into considerations. Free-sprung escapements aren´t new and in use by other brands already, but there´s no hard and fixed rule how to fit in such mechanism into the specific needs of a specific caliber.
And if one thing, it should be worth the efforts, in that it offers noteworthy improvement.

GP went all the way and, as you may see, came up with a special solution:
Unlike most other free-sprung escapements, the balance wheel of the new MICROVAR escapement is fitted with two different sort of adjustable weights.

Outside of the balance wheel circumference, a number of 6 tiny screws made of solid gold are mounted. These screws account for proper poising - the weight all over the balance is perfectly equilibrating by widening/shortening the diameter of the balance when screwing in or unscrewing one of these screws.

On top of the balance, a number of two adjustable weights made of Glucydur are mounted. These excentric weights account for the rate of the watch and, in a simplified view, cause it to run faster or slower.

The combination of both allows for extremely fine adjustment and regulation, without need to disturb the natural breathing of the hairspring.
And not only this - all screws and weights are set into recessed cut-out areas as not to influence the proper beating of the watch by aerodynamic turbulences.
Both together result in variable inertia of the balance, which can be tuned to fit the escapement components and watch parts perfectly.

But that´s not where it ends - the new MICROVAR balance is accompanied by an unique swan´s neck fine adjustment mechanism!
What looks like a conventional swan´s neck regulation system actually allows to set the beat rate of the watch. This, simplified, adresses the intervals between the "tick" and "tack" in one beat of the escapement.
This allows to regulate the watch even more precisely, which is promising a better timekeeping as well.

As you see, GP truly went all the way!
The new MICROVAR system is a most elaborate way to address a seemingly simple problem - how to make a watch run more accurately.
And it´s far more elaborate; the efforts on production and assembly level are tremendous as any part needs to be manufactured, assembled and regulated very precisely.
But then, given the background i´m under the impression the new MICROVAR is an excellent addition and fits perfectly into past achievements of the brand.

I´ll leave the details to an extended and more elaborate introduction to come at some later point.
Nonetheless i do hope the new MICROVAR balance is something you do look forward to see - at least knowing the watch to bear it will be as special as it´s movement...
So there´s more to come

With thanks to GP Suisse!

Greetings from Germany,

Peter

(pictures in this post are exclusive for the GP Forum at Watchprosite.com and shall not be reproduced elsewhere)

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