In March 2012, Chopard Manufacture unveiled the L.U.C 8HF housing the L.U.C. 01.06-L movement complete with the world's first high-frequency (8Hz) escapement to be COSC accredited. Beating at 75,000 vibrations per hour, the new escapement is compatible with almost all existing L.U.C. movements. QP takes a closer look.
When watchmakers and escapement makers of the mid-1960s first upped the ante with high-frequency escapements, they correctly believed that they were onto something - namely an important advance in chronometry. Some very old watches have escapements that beat 14,400 times an hour - a speed known as 2Hz. Horologists commonly refer to an oscillator's vibrations per hour - the vibration in this context being a swing from left to right of the balance, which is only half of a physicist's oscillation, which is a complete return of the balance from it's start to its furthest point and back again. 1 Herz (Hz) is therefore 2 vibrations.
Slowly, advances in our understanding of what makes oscillators stable, coupled with improvements in metallurgy and mechanical technique, resulted in watches being made with ever faster-ticking escapements. The peak in this operating frequency, for much of the 20th century, was 36,000 vibrations per hour (5Hz).
Chopard's L.U.C. 8HF housing the L.U.C. 01.06-L
movement features the world's first high-frequency escapement -
running at a speed of 8Hz - to be COSC accredited.
In spite of all the excitement, however, it wasn't long before most producers began to quietly scale back the frequencies of their movements. Troubles that were related to horology's perennial enemies started to develop: lubrication, the issue of metallurgy and problems with manufacturing precision. At these high frequencies, oils that were sufficiently light and liquid enough not to stop the watch would be flung off the moving parts by the violent amounts of kinetic energy being dissipated (microjoules, I assure you). The metallurgical limits of the watch springs were being stretched to beyond what was reasonable and manufacturing tolerances simply were't up to the micro-metre precision demanded by these high-performance devices.
The right time
The intervening few decades, however, have given horology the opportunity to re-group. High-frequencies are still one of the better ways to improve the precision of watches and now technology and materials science have presented tools that get around the previously intractable issues that saw the pace, as it were, of chronometry slow down in the 1970s.
The
small red hands indicating the seconds in the 6 o'clock position
move with a smoother action than the hands on ordinary watches due
to the high-frequency escapement.
Chopard Manufacture has combined much of what is now known about the subject into a single, alluring high-frequency watch. Certainly, other high frequency watches have been made along similar lines in recent years, but what makes the new Chopard L.U.C. 8HF unusual, say the makers, is that it is the first of its kind to have passed the standardised Swiss COSC timekeeping test. The COSC test is a universally-understood measure of wristwatch stability; it would not detract from the test to point out that the horological industry at large now excels at producing millions of movements per year that easily pass the test. It's still a fiendishly difficult set of rules, in pure terms, and Chopard must be applauded for succeeding at it with such a new calibre.
The £12,410 model will be produced in a limited edition comprising only 100 examples. It has an 8Hz escapement, double that of a typical watch, meaning the escapement purrs along at a sweet 57,600 vibrations per hour.
There are two possible ways by which an increase in frequency represents an improvement in timekeeping: first, it presents us with a finer resolution by which to examine the time. If you had, say, a perfect oscillator, but an escapement that beat only once every half a second, you could not harness the oscillator's perfection to any closer limits than half a second (the oscillator keeps moving all the time-its precision is not quantised the way the actual ticking of a watch is). So a fine resolution is an important way to extract high-precision data out of a watch.
Secondly, finer subdivisions represent smaller intervals in which mechanical errors and disturbances can feed back and forth between the escapement and the wheel train. An oversimplified way to explain it might be to say that a watch ticking 57,600 times an hour suffers a smaller total error by missing a beat than does an 18,000 v/hr watch under the same circumstances.
This
model is distinguished by the crown, positioned in the 4 o'clock
position, which is made from titanium and bears the L.U.C.
logo.
Technological revolution
The watchmakers and engineers at Chopard Technologies in Fleurier took four years to devise this system, mindful that one of their overriding aims was, interestingly, to make the escapement compatible with most of their existing calibres, swappable retrospectively. This means very careful attention to details such as gear ratios of the wheel train (one can't have the watch hands moving at twice normal speed), and the power source, which would otherwise have to be excessively strong to match a strengthened high-frequency balance spring. Chopard claims the movement in the 8HF has the same power reserve (60 hours) as one of their similar ordinary calibres, and uses a mainspring of the same strength.
Much of the advantage gained with this new calibre is derived from the use of etched silicon components. The escape wheel (whose very carefully-shaped 40 teeth require extreme lightness and absolute precision in their shape and placement upon their axis), lever and impulse pin are all produced using the ultra-high precision technology inherited from the semiconductor industry, which manages to cram thousands of millions of transistors onto microchips an inch square. Their astonishing mechanical tolerance of less than the wavelength of light are somewhat lost on horology's humbler requirements of mere thousandths of a millimetre.
Working with innovative material technology to create
the ultra-fast movement, the engineers at Chopard Technologies used
silicon for certain escapement components, developing a new way of
fixing silicon onto steel in the process.
A further advantage in using this technology, well-established by now in horology, is the tribological gain afforded by parts made of pure crystalline silicon (post-treated or otherwise) when interacting with steel (or other silicon) components: friction reduction is so enormous that the need to even consider it is negated: the co-efficients of friction of the various parts so produced are so small that they can just about be ignored.
Case closed
Finally, the 8HF is housed in a magnificent case, made in two parts: the caseback, milled from the solid along with the lugs, is bolted to the topmost part using ten socket-head cap screws. The lower part is treated to a spell in an electro-plasma chamber, where the Grade 5 titanium's micro-structure is altered, rendering it less crystalline, much harder, and more ceramic-like, while remaining, fundamentally, a metal.
To the outside world, the watch presents a clean contemporary appearance, the only allusion to its rarity being a dynamic red glyph below the makers' name on the beautifully silvered dial. High discretion, as ever, is added to the twin accolades of high-precision and high frequency, from the masters at Fleurier.
Further information: www.chopard.com
