W102659 USA 15
Size: W227 x H305mm
m.chen
2nd
W102659 USA 15
Size: W227 x H305mm
m.chen
P ri m e T i m e
1st
P ri m e T i m e
DEWITT CALIBER DW 8014
THE POWER OF THE PERIPHERAL
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DeWitt’s new caliber is one of the world’s most innovative automatic-winding movements as well as a fascinatingly executed deadbeat-seconds tourbillon By wei koh
W102569-PrimeTime - Dewitt KL.indd 82-83
AUTOMATIC SIDEWINDING Now, the idea of a peripheral rotor has appeared before in watchmaking history — notably with Patek Philippe’s 1968 patent and, most recently (and resoundingly successfully) with Carl F. Bucherer’s cal. CFB A1000. A peripheral-winding movement is, of course, in theory a brilliant idea with two clear advantages. The first is that you retain a clear unobstructed view of the movement — that enticing engine powering your timepiece. The second is that you can create complicated movements without worrying about having to design the complication around the automatic-winding system, whose central axis is usually right in the center of the movement. Integrating a complicated movement and an automatic-winding system has been a challenge that has longed frustrated watchmakers; it was, for instance, the reason that it wasn’t until 1969 that the first automatic chronographs were finally produced.
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The inner world of Dewitt’s DW 8014 in-house manufactured movement 1 The peripheral oscillating mass is attached to a ring
of metal composed of a nickel-phosphorus alloy, created using LIGA technology, whose inner edge has a sinusoidal shape fabricated to within one-micron tolerances 2 The peripheral mass is made of “heavy metal” 3 The entire rotor runs on zirconium-oxide ceramic ball bearings 4 The rotor is mounted to these elements, which feature hidden silent blocks to absorb shock 5 The third wheel here drives the pinion of the tourbillon cage. 6 This wheel is fixed to the tourbillon cage and powers the deadbeat-seconds mechanism 7 This spring loads the deadbeat-seconds mechanism 8 This spring-loaded element made from spark-eroded steel drags the seconds wheel forward in one-second increments 9 This small pinion places a load on the spring-loaded element, so that it detaches itself and pulls forward on the next tooth of the seconds wheel 10 This is the seconds wheel that is activated precisely once each second
But what is truly impressive is how the DW 8014 utilizes a brilliantly logical innovation to create a bi-directional winding system in conjunction with its peripheral mass. This movement’s super slick winding rotor with ceramic ball bearings is actually constructed in two parts: an oscillating mass made of what DeWitt has amusingly termed “heavy metal” and, attached to it, a nickel-phosphorus ring whose inner edge has a sinusoidal profile — a precisely shaped wave crafted with LIGA technology to within one-micron tolerances. Why the fuss over this sinusoidal profile, you ask? Good question. Explains the brand’s managing director Nathalie Veysset, “This element must be crafted to within a micron tolerance, because its particular wave-shaped structure interacts with two small winding arms to wind up the mainspring.”
These two small winding arms are actually the two ends of a single centrally pivoted lever with jeweled rollers at their points of contact with the wave-shaped inner contour of the nickel-phosphorus ring. As the ring rotates — carried by the “heavy metal” oscillating mass — the rollers ride up and down the wave-shaped inner surface of the ring. This causes the winding arm to rock on its pivot, and this rocking motion is transmitted to a pawl, which is geared to the first wheel in the automatic-winding train. The pawl idles in one direction and engages the teeth of the wheel in the other, winding the mainspring. Conceptually, it’s related to such winding systems as the IWC Pellaton system, which also uses a rocker and pawl mechanism, but it’s almost as if that system had been turned — so to speak — inside out.
REVOLUTION H 083
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’ve long considered DeWitt to be one of watchmaking’s best-kept secrets — something of an under-the-radar, insider’s secret Since its inception, DeWitt has gone from strength to strength, formalizing and reinforcing its unique blend of classical watchmaking values, with audacious design and a groundbreaking re-envisioning of the world of high complications. For example, by now everyone knows that the minute repeater was created so gentlemen could tell time in the dark, and thus appropriately jettison bed-warming scullery maids before their spouses return from the opera. But in today’s perennial thousand-candle-watt world, it is charmingly anachronistic. It took Jérôme de Witt to re-express this complication’s relevance through the creation of the Répétition Minutes Tourbillon GMT Antipode: the world’s first dual-faced GMT tourbillon wristwatch, where home time is played on the watch’s repeater even when a different local time is displayed by the hands. Ingenious? Absolutely, and let’s not even discuss the spectacular voice of the cathedral-gonged repeater as it literally peals off sonic magic through the interaction with its sapphire dial and titanium case. Jérôme de Witt’s signature style is his perfect marriage of pragmatism — take, for example, his ultra-legible perpetual calendar or triple-complication watches — with a certain gentlemanly elegance to which he can lay claim both by achievement and ancestry — he is, after all, a descendant of Napoleon Bonaparte. In an industry where progress is too often a matter of predictable and minutely incremental variations on timeworn themes, de Witt’s is one of the few watchmaking minds that have the capacity to constantly surprise me. And take, for instance, the birth of the DW 8014, his second fully in-house created movement after the DW 8028 (for the Twenty8-Eight Tourbillon). It was a few years ago that he said, “I want to create an automatic-winding movement, but one that doesn’t use a traditional rotor. I want to place the rotor at the outside of the movement, at its perimeter.”
7/16/10 4:13:54 PM
W102659 USA 15
Size: W227 x H305mm
m.chen
1st
W102659 USA 15
Size: W227 x H305mm
m.chen
P ri m e T i m e
2nd
P ri m e T i m e
Sinusoidal shaped nickel phosphorus ring
Ruby rollers Rocker arm When power in the barrel is 60 percent full, the movement’s power reserve mechanism causes the pawl to disengage from the ratchet wheel
Ratchet Wheel Pawl
However, the design of the system raises a significant question: what happens when the rotor receives a shock? Veysset explains, “The teeth of the wheel wound by the pawl has a special profile that allows the pawl to slip off it and momentarily disengage. In addition, the entire peripheral mass as well as the two small winding arms are mounted on silent blocks that act as shock absorbers.” But the advances in winding don’t stop here. Because one problem with automatic movements is that the amplitude of the balance wheel varies significantly with the movement’s state of wind. A full barrel — wound above 60 percent — exerts significantly greater torque on the gear train, in turn causing an increase in balance amplitude which may cause the watch to run slower, while a barrel that drops below 30 percent transmits less power to the balance, causing a loss of amplitude, which may result in the watch running faster. Jérôme de Witt was absolutely determined to address this issue in
W102569-PrimeTime - Dewitt KL.indd 84-85
his automatic caliber and so created a special system that limits the state of wind of the movement, so that it never drops below 30 percent or exceeds 60 percent. De Witt explains, “In the movement, when the barrel reaches 60 percent, it triggers an element in the power reserve indicator that disengages the pawl from winding the barrel.” Says de Witt, “The result is a movement with a torque curve that is [almost] absolutely flat. Amusingly, I had started with the simple desire to create an all-new automatic movement, but as we neared completion, I felt that I wanted to add something more to this first execution of our caliber. So a tourbillon became part of the movement. Now, because a tourbillon is quite a bit heavier than a normal escapement, we checked to see the results on our amplitude. Because of the efficiency of our winding system, we found that the watch was almost always at 60-percent power with a totally flat torque curve and consistent amplitude. So then I had the idea that perhaps we can go one step further!”
“In the movement, when the barrel reaches 60 percent, it triggers an element in the power reserve indicator that disengages the pawl from winding the barrel” — DeWitt CEO, Jérôme de Witt
DEADBEAT SECONDS A deadbeat-seconds mechanism is a system that causes the seconds hand of a watch to advance only once per second. This complication first appeared in tower clocks at the end of the 17th century. Amusingly, in the 1970s, Rolex began to produce deadbeat-seconds wristwatches to replicate the ticking of quartz-watch seconds hands, but in fact the rationale behind these watches was to give the highest precision as to the precise striking of each second. In wristwatches such as the Rolex Tru-Beat, a parasitical system was created for a seconds hand that ticked only once a second. But the problem was this system robbed the balance wheel of amplitude, in particular, when the barrel was low. Says Nathalie Veysset, “Mr de Witt’s idea was that because our movement is almost always at 60 percent with perfect constant amplitude, we could implement a deadbeat-seconds system almost as a demonstration of the quality and consistency in power generated by the DW 8014.”
The deadbeat-seconds system that was created, again, is a marvel of logic and simplicity. A wheel attached to the tourbillon cage places pressure on the seconds wheel using a pinion. This wheel places pressure on a spring-loaded mechanism, so that every second it slips forward, it pulls the next tooth of the seconds wheel forward, causing the seconds hand to advance. Because of specially shaped teeth for the seconds wheel, very little sliding friction occurs throughout this process and loss of amplitude is only a few degrees each time the seconds advances, which is totally negligible on a movement with such constant torque. This system is the first-ever created in which the deadbeatseconds complication is directly driven by the tourbillon carriage. In one move, Jérôme de Witt has created both the world’s most advanced automatic-winding watch and its most fascinatingly executed deadbeat-seconds tourbillon — a demonstration of the spectacular horological advancement that has become synonymous with the name DeWitt. H
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The nickel-phosphorus ring’s sinusoidal profile causes movement of the rocker arms via their ruby rollers, moving a pawl that winds the barrel. This system functions in both directions of rotation, without the use of reverser wheels
7/16/10 4:13:59 PM