The neglected Rolex balance clearance fine-tuning system

Each revolution in movement technology is an exploration of the frontiers of mechanical watchmaking, which may go down in history or be short-lived, but replica replica Rolex Day Date watches the infinite possibilities are always the ones that tug at the heartstrings of watch lovers. Rolex, a famous Geneva-based watchmaking company, is a legend in the world of watchmaking, with no superlative complications, no finely polished movements, and no limited editions.

Top: Journal type equipped with calibre 3235 Bottom: Day calendar type equipped with calibre 3255
Top: Journal type equipped with calibre 3235 Bottom: Day calendar type equipped with calibre 3255

Since the middle of the last century, the shapes of Rolex’s major collections have evolved subtly without ever deviating from the norm, and the technology of the movements has continued to break new ground and evolve, but rarely on the surface, so much so that without careful questioning, you can’t be sure exactly how different the watch and the movement are from what they used to be. Last year (2015), Rolex unveiled two new calibers: the Cal.3235 and the Cal.3255. The Cal.3055 came along with the Cal.3155 when the Cal.3135 replaced the Cal.3035 in 1988.

Cal.3035 to Cal.3135, and Cal.3135 to Cal.3235 – basically the layout of the movement. A very significant adjustment has been made, and the difference between these numbers is obvious. The difference between the Cal.3135 and Cal.3136 is mainly due to the change of the shock absorber KIF to the Rolex patented Paraflex, while the change of the numbering of the movement is a direct consequence of the complete change in the function and type of movement, indicating two completely different movements.

Rolex's important 3 series movement evolution
Rolex’s important 3 series movement evolution

So the Cal.3255, new for 2015, is fundamentally different from the previous Cal.3155, but not yet beyond the type of movement; they are both exclusive to day of the week calendar-type watches (DD for short). So what’s the difference? I think most of the differences were already known at the beginning of the year, such as the 50% reduction in the barrel wall, the new paramagnetic Chronergy escapement (15% more efficient), the 50% slimmer escapement fork tile, the increase in the power reserve to 70 hours, the redesign or modification of more than 90% of the movement’s components, the doubling of the accuracy of the original chronometer-certified movement, and the 14 patents! And so on. But there is one rather detailed change that is less well known, a modest but conspicuous change that should in fact not be overlooked, and that is the fine adjustment screws on the swing bridge plate.

Speaking of this fine adjustment screw, it was first introduced in the 3XXX base movement, but not until 2015, so it’s not new technology, but it’s a modest change to Cal.3235 or Cal.3255. Before we get to the fine-tuning screw, the first thing we’ll talk about is the fine-tuning screw hidden underneath it, in Cal.3235/Cal.3255, the balance bridge has been very significantly modified compared to its predecessor, except for the fact that the clip that used to hold it in place with a screw above the bridge has disappeared, and the two fine-tuning screws that used to be underneath the bridge are now only one. The function of these screws is to fine-tune the amount of balance clearance by adjusting the position of the bridge plate, during the installation process, the position deviation of the bridge plate will directly affect the position of the pendulum, thus affecting the running time. These two fine-tuning screws, which have been available since Rolex transitioned from the single bridges (bars) of the 30XX, to the 31XX series of movements, show that while the two-arm bridges are more stable and reliable than the original single-arm bridges, and have better positional accuracy, they are not perfect, and there is no room for fine-tuning in the event of positional deviations.

Two fine adjustment screws in the Rolex Cal.3130 movement
Two fine adjustment screws in the Rolex Cal.3130 movement

In all modern Rolex movements, as long as the balance structure of the double arm bridges, there is a fine-tuning structure under the bridges, a move that ensures that even after years of use, if the pendulum or the bridges are out of position, there is still a way to make adjustments without having to replace parts, which provides greater convenience for later maintenance and repair. As the advantages of the stability of the double-arm bridges have become more well known, many brands are using them, such as the new generation of coaxial movements such as Omega’s 85xx and 9xxx series, as well as Audemars Piguet, Jaeger-LeCoultre, Piaget, etc., but without exception, with the exception of Rolex, which uses fine-adjustment screws under the pendulum bridges, none of the other brands have a similar fine-adjustment structure (patent implications?). (I wonder if any of my cousins know about this).

In Rolex’s 31XX series movements, underneath the bridges were two micro-adjustment screws, their edges, both partially exposed, and the baseplate next to them would leave some space for tools to fine-tune the two screws. With the 2015 32XX line of movements, this all changed, the micro-adjustment screw on one side of the bridge plate was eliminated and the other side was still there, but out of thin air, a graduated micro-adjustment screw appeared. In the official Rolex literature, this structure is ignored because it is not new technology and has been “in use” for 16 years.

The fine-tuning screw, in fact, has a gear underneath and engages with the original fine-tuning screw at the bottom. The advantage of having scales is obvious, as they are very easy to quantify and the amount of fine adjustment that can be made per scale should be documented in the official internals. The elimination of a single fine adjustment screw is probably due to the fact that unilateral fine adjustments are considered sufficient, and two-sided fine adjustments are inevitably more cumbersome and less accurate than one side. As previously mentioned, this technology is not new, and looking at all recent Rolex movements, the structure has been in its infancy since the introduction of the 2230 (2235) in 1999, when the additional fine adjustment screw, which was not yet graduated or integrated into the balance bridge, was introduced.

By the year 2000, following a series of changes in the structure of the movement and its components, the Cal. 4130 chronograph movement using this structure, which replaced the 4030 calibre that had been in use for eleven years since 1989, was also semi-integrated into the balance-plate (in 2235, the fine adjustment screw was not secured by a whole plate, in 4130, it shared the balance-plate with the fine adjustment screw). In 2012, the Rolex Sky-Dweller was launched, equipped with the new Cal.9001 automatic movement developed by Rolex, and instead of making the fine-tuning structure of the bridge more streamlined, it became much more complex, with two fine-tuning screws of the 31XX series, one next to each of the fine-tuning screws, and one fine-tuning screw on the bottom of the bridge. “Hide” it.

By 2015 in the 32XX series, the entire fine-tuned structure of the original 41XX series movement was simply integrated into the oscillating bridge plate, and also made to scale. So, it’s not a new technology, but it has evolved, even more so in the 3XXX series for the first time. Rolex movements have always been known for their precision and durability, and behind this, in addition to having many special materials and structures patented by Rolex, a more important point is that most of the components in a Rolex movement can be readjusted at a later stage of maintenance, rather than having to be replaced, so that even a Rolex watch from decades ago can still keep time accurately after maintenance. The silicon hairspring, which was very popular a few years ago, is also fading away in recent years. The main reason is that silicon is too brittle and can only be replaced when damaged. So a really good watch, in addition to good to go now, decades or even hundreds of years later, whether it is easy to be saved is equally important, and undoubtedly, Rolex durability is also reflected in this point.

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