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precision timing

Jaeger-LeCoultre’s spectacular double win at last year’s international chronometry competition in Le Locle has sparked renewed interest in the tourbillon — but was it proof positive of the tourbillon’s benefits, or a staggering stroke of luck? By ELIZABETH DOERR

he Concours de Chronométrie, held for the first time last year, was an event eagerly anticipated by watch enthusiasts — it was the first open chronometric competition since the last observatory competition in 1967. And the results announced on 3 December 2009 were nothing short of spectacularly surprising: Jaeger-LeCoultre took both first and second places in the competition. With tourbillon models.

Why the surprise? After all, the tourbillon was originally invented by Abraham-Louis Breguet precisely for the purpose of improving chronometry. But today, enthusiasts debate vigorously over whether the tourbillon actually provides a significant chronometric advantage — particularly in wristwatches, which unlike pocket watches

do not spend the lion’s share of their time in the vertical positions for whose errors the tourbillon was designed to compensate.

Experts have weighed in on the point as well. For instance, in the standard reference work Das Tourbillon (Callwey, 1993), author and watchmaker Reinhard Meis spends about five pages discussing the chronometric value of the tourbillon as compared to standard chronometers tested in observatories, in the chapter, “Is it worth making a tourbillon?” The data from earlier observatory competitions shows that rates between tested tourbillons and tested chronometers were not really much different.

“The rate results show that the difference between normal pocket watches and tourbillons was not so great that making a tourbillon would have been necessary,” he

concludes. “Naturally, in Breguet’s time, the tourbillon was a true improvement. But in the ensuing 100 years, so much progression was evident in precision watchmaking — both in normal watches and in tourbillons — that they have kept pace with each other.”

Yet the results from the Concours de Chronométrie have opened the question once again. The 16 watches entered were scored as follows: if they showed no rate deviation throughout the testing process, they obtained a perfect score of 1,000 points.

Each second of deviation measured was one point taken from this score. JaegerLeCoultre’s Master Tourbillon won with a score of 909 points, while the brand’s Reverso Gyrotourbillon 2 came in just one point behind its sister. The third-placed watch had 906 points; it is believed to

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CLOCKWISE FROM LEFT The caliber 174 of the Reverso Gyrotourbillon 2 by Jaeger-LeCoultre which scored high marks at the Concours de Chronométrie; JLC’s Master Tourbillon took top spot at the competition; Jaeger-LeCoultre ’s marketing director Stéphane Belmont points out that the company is highly dedicated to precise timekeeping OPPOSITE The Reverso Gyrotourbillon 2

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T i m e c o m p l i c at i o n Stephen Forsey (left), one-half of haute horloger Greubel Forsey; Greubel Forsey’s multi-axis tourbillon timepieces, such as the Double Tourbillon 30° Vision pictured here, are designed to adapt the tourbillon to the wristwatch

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be a time-only specimen (the full results were not made public), and it was almost 100 points ahead of number four.

These results automatically lead one to question if the scores were obtained because tourbillons actually do what they are supposed to, or if there were other factors involved. Jaeger-LeCoultre’s marketing director Stéphane Belmont does not necessarily chalk his company’s win up to the fact that the watches were tourbillons.

“The basic premise in watchmaking is this: the more complicated a movement is, the more sensitive it is. Not so here; ours must outperform the regular watch,” he explains,

though he also comments, “For us, it is not just a high-tech watch, but one of the most precise according to the tradition of watchmaking. Our tradition is to improve the mechanics to have better performance — including precision.”

The independent opinion There’s no doubt that the increasing ubiquity of the tourbillon has given ammunition to those who feel its primary advantages are aesthetics (and marketing). When the multi-axis tourbillon specialist Greubel Forsey first gauged the market in 1999, only 35 brands offered tourbillon models at all.

By the time Greubel Forsey launched in 2004, the number had increased to 100. “It has become a more ‘standard’ complication,” Stephen Forsey remarks. “This can be partially explained by new technologies like CNC machines and CAD designs as well as the visual appeal of the tourbillon systems for new collectors.” Greubel Forsey’s own tourbillons are explicitly designed to adapt the tourbillon chronometrically to the wristwatch. But as Stephen Forsey has remarked to REVHLUTION, “It’s always a struggle to gain more than you lose.”

“With the tourbillon, we face the same problems as the normal watch,” says Kari

LEFT Philippe and Thierry Stern of Patek Philippe, one of the few companies that disclose the accuracy its wristwatches must attain ABOVE The Patek Philippe Ref. 5339 tourbillon with minute repeater

Voutilainen, an independent master watchmaker who submitted a movement to the Concours de Chronométrie. “We have to prepare the escapement and balance it properly, poise it, and give the hairspring the correct pinning point in order to get correct timing. The hairspring has to have the right length to have perfect isochronism.

In my opinion, the reason for the results of the competition was the time involved.

Jaeger-LeCoultre had a complete team working on this project; for them, it is convenient and easy to pick the best watches from their production and work them.”

Tourbillon specialist Thomas Prescher

sums up his love of tourbillons in one word: art. “In my opinion, tourbillons do not automatically lead to a noticeable improvement in rate. Every watchmaker has learnt to perform precision regulation that would beat the prerequisites of official chronometer certification by a mile. But you need good materials and production methods, particularly with regard to the balance spring and balance, but also the rest of the movement.”

Sealed numbers Patek Philippe’s new seal — which replaces the Geneva-based brand’s participation in

the Geneva Seal — officially discloses the rates that the company’s wristwatches must achieve before it can bear the in-house certification. All — including the tourbillons — are COSC-certified as the base. “A Patek Philippe watch is first and foremost an instrument that measures time,” the Patek Philippe Seal stipulates before making a binding statement regarding rate accuracy.

The company thus assures its clients that its tourbillons are subjected to the same inspections as all its other mechanical timepieces, but must comply with even tighter tolerances. The accuracy stipulated during final inspection with kinetic

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When the multi-axis tourbillon specialist Greubel Forsey first gauged the market in 1999, only 35 brands offered tourbillon models. by the time greubel forsey launched in 2004, the number had increased to 100

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simulators must lie within the range of -2 and +1 seconds per 24-hour period (nontourbillon mechanical calibers with diameters of 20mm or more must range between -3 and +2 seconds per 24 hours, while calibers with diameters smaller than 20mm must range between -5 and +4 seconds per 24 hours). Additionally, the greatest deviation between the average rate of the watch in all six measuring positions and the rate in each individual position must not exceed four seconds in 24 hours.

Other than this, very few brands are willing to disclose specific statistics regarding the rate accuracy of their tourbillons. The chronometry competition provided numbers for the two Jaeger-LeCoultre pieces, which are far under the ISO norm (see chart on page 263). The winning Master Tourbillon was even under the ranges Patek Philippe specifies in its in-house seal. Stéphane Belmont explains that this version of the Master Tourbillon submitted was “the regular version, exactly the same watch as in

stores. Naturally it had some extra regulating, a bit of a stabilizing period, and then a little more fine-tuning and adjustment.”

The second-placed Reverso Gyrotourbillon 2 was a little different, though, and its numbers reflected this. “We tested some new solutions like a new balance wheel, whose shape is very similar to that of the Master Compressor Extreme LAB with some new materials. It was kind of like ‘let’s see what we come up with here’.”

A few seconds Denis Flageollet, technical director of De Bethune, explains that his tourbillon, which boasts a design that was developed especially for the wristwatch, has low inertia, a high frequency, rapid gyration, and non-magnetic elements “with virtually no need of lubrication. The average rate [of deviation] is a few seconds a day over the course of the five-day power reserve.”

Ulysse Nardin reports very good results with the new Freak Diavolo. Technical

director Pierre Gygax explains in greater detail, “Usually, a tourbillon cage consumes a lot of energy, which leads to using a lower frequency (i.e., 3Hz instead of 4Hz) and a smaller balance wheel. Therefore, the advantage brought by the tourbillon to offset vertical position discrepancy is lost by the intrinsic lower potential of precision of the oscillator.” It is important to note that Gygax does not attribute the Freak Diavolo’s reported good rate to the tourbillon itself, but to the new materials used in the movement.

While Cartier will not release any chronometric numbers for its complicated timepieces, the company’s head of fine watchmaking movements Carole ForestierKasapi has some interesting thoughts on the state of the tourbillon.

“The commercial popularity of the tourbillon these last years has encouraged the emergence of watches with average performances. A tourbillon is supposed to be the showpiece of fine watchmaking with

Impressive results have been reported by Ulysse Nardin with the new Freak Diavolo, in part due to the new materials used in the movement

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Thomas Prescher, a tourbillon specialist, notes that a tourbillon does not immediately equate to an improvement in accuracy RIGHT Thomas Prescher's Triple-Axis Tourbillon

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The Concours International de ChronomÉtrie

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good chronometry,” she explains. “There are good and bad watches outfitted with both tourbillon escapements and classic escapements. Fortunately, there are also brands that offer tourbillons with the type of chronometric excellence that we can expect from this complication.”

Forestier-Kasapi says that the fact that the winners of the chronometry competition were tourbillons proves nothing. “They were the movements with the best regulation; it was ‘only’ the design, the preparation and the adjustment of these movements that enabled them to win.”

Richard Habring reports that numbers on the Habring2 Tourbillon 3D “are not better or worse than the average of all our watches”.

The movement base for the Habring2 watch is the ETA Unitas 6498-1 with a power reserve of 44 hours. “With a low-amplitude beat in a 24-hour period, we see a rate deviation of two to three seconds per day.”

Well made “In my opinion, the tourbillon watch has to be very well made to be able to keep proper time. More complicated, it takes more time to assemble and work with,” says Voutilainen.

Prescher has a scientific view about this.

“According to my information, only in recent years have the rates of wristwatch tourbillons developed far enough to arrive at chronometer rates.” He attributes the improved “exceptional rates” to the use of new materials and production methods.

“Earlier tourbillons, like those that were successful in chronometer competitions, often had larger balances and were kept

stationary,” he explains. “To be fair, it must be said that every watch that achieves such rates in a chronometer competition — whether a tourbillon or not — is a masterpiece needing several days of work by a competent specialist. My opinion is that the Jaeger-LeCoultre tourbillons won because a team of specialists worked in an exceptional manner. And this includes production, movement design, assembly and regulation. In this day and age, an achievement like that has to be teamwork and not the work of one individual.”

The future of tourbillons “In the coming years [it is certain that] no one will be in a position to measure what results can be attributed to the intrinsic quality of the tourbillon and what can be attributed to the dexterity of the watchmaker who has dedicated numerous months in the exclusive preparation of a movement for a specific competition,” Flageollet theorizes on the use of new materials to improve overall chronometric rates.

While in Breguet’s time, the tourbillon provided revolutionary rate improvement — probably due to a handful of factors — experts tend to agree today that the tourbillon as an isolated element does not single-handedly improve the rate of a wristwatch.

The tourbillon is perhaps best summed up with Thomas Prescher’s point of view in mind. “For myself, I see watchmaking as an art form and try to create unusual technology and aesthetics. Despite this, all of my watches are delivered with a protocol of

2009 Results

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VG diagram key

Red - The red line measures the variation of a fixed escapement without tourbillon function (inner oneminute cage removed from a Double Tourbillon 30° and driven as a simple fixed escapement). In this example, the result is a maximum delta of 10 seconds per day between crown down and dial up.

Blue - The blue line shows the same inner cage working (without adjustment) as a single-axis wristwatch tourbillon; we now have an improved delta of seven seconds per day. Like a pocket watch, no tourbillon effect is visible in the horizontal position. According to Forsey, this shows “the typical weakness of single-axis flat tourbillons”.

Green - The green line depicts the (unadjusted) result of the inner cage remounted in the Double Tourbillon 30° system. It also shows the maximum delta between the two extremes of the six positions reduced to 3.5 seconds per day thanks to the Greubel Forsey Double Tourbillon 30° system.

ABOVE Results of Greubel Forsey's laboratory test on the Double Tourbillon 30°, in the six positions that the watch is tested in

esting of the timepieces was carried out at three different locations, first at the Besançon observatory (N1), followed by the COSC in Bienne (N2). The timepieces were then tested at the HE-Arc in Le Locle for vulnerabilities in exposure to magnetic fields and shocks, before a final test at the COSC in Bienne again (N3). A jury comprising Mr Michel Mayor, astrophysicist of the Geneva Observatory, Mr LaurentGuy Bernier of the METAS Federal Office of Meteorology, and astronaut Mr Claude Nicollier were there to observe the results. Timepieces that failed to achieve the ISO-3159 standards during the test were eliminated, and points were

Criteria Mmoy Vmoy Vmax

Rank

deducted from a total of 1,000 based on the variations of the timepieces in the seven different tests, which were calculated according to ISO-3159 standards.

The competition was made open to individuals, schools and watchmaking companies and movement suppliers. The participant had to have assembled, adjusted and set the piece internally. This was mandatory.

In the tests, Jaeger-LeCoultre’s Master Tourbillon equipped with the caliber 978 emerged in top position, while the Reverso Gyrotourbillon 2 took second position. Results of the first four timepieces are indicated in the chart below.

N1

N2

N3 Rank

N1

N2

N3

Average daytime rate

0.47

0.75

-1.09

1.31

3.19

2.39

Mmoy

-4

6

Average rate variation

0.16

0.13

0.08

0.39

0.12

0.25

Vmoy

<

2

0.28

0.19

0.16

0.83

0.16

0.60

Vmax

<

5

-1.19

-0.57

-1.32

Greatest rate variation

D

Difference in rates between vertical and horizontal positions

P

Greatest difference in rates

1.22

0.67

C

Variation in rate based on temperature changes

0.02

0.06

R

1

0.17

-0.39 -0.65

D

-6

8

1.02

0.51

0.28

0.50

P

<

10

0.03

0.01

-0.03 -0.02

C

-0.6

1

Rate correction

-0.25 -0.25 0.09

0.19

0.29

0.59

R

-5

5

Points awarded

906

910

913

892

914

Criteria

907 909

Final Result

their chronometric values.”

According to Stephen Forsey, tourbillons really can be more precise. His graph above shows proven results from Greubel Forsey laboratory tests on a Double Tourbillon 30°. “This is a scientific approach where no adjustments were made between the three different tests. It shows the maximum variation in seconds per day between six standard positions,” he says. As an aside, the COSC only tests five positions. H

2

ISO 3159

Rank

908

N1

N2

N3 Rank

N1

N2

N3

ISO 3159

Mmoy

Average daytime rate

0.54

1.27

1.78

-1.37

-0.92 -0.58 Mmoy

-4

6

Vmoy

Average rate variation

0.15

0.07

0.11

0.87

0.43

0.14

Vmoy

<

2

0.27

0.17

0.14

1.56

0.89

0.25

Vmax

<

5

Vmax

Greatest rate variation

D

Difference in rates between vertical and horizontal positions

P

Greatest difference in rates

0.23

0.40

0.22

C

Variation in rate based on temperature changes

0.08

0.10

R

Rate correction

0.60

0.15

Points awarded

921

900

Final Result

3

-0.03 -0.50 -0.14

4

D

-6

8

0.87

P

<

10

0.13

-0.04 -0.08 -0.13

C

-0.6

1

0.42

-0.59

-1.14

-0.72

R

-5

5

890

810

833

854

906

-0.38 -0.96 -1.20 1.55

1.24

828

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experts tend to agree today that the tourbillon as an isolated element does not single-handedly improve the rate of a wristwatch