BLANCPAIN – Le Brassus, “8 Jours” (8 Days) Platinum

Introduced in 2006, this exceptional mechanical watch in platinum is equipped with a hand wound movement that delivers power reserve up to 8 days. Equipped with a titanium balance with an adjusting screw system, a Breguet overcoil balance-spring and three barrels ensuring an 8-day power reserve, Calibre 13R0 represents the fruit of an assiduous quest for simplicity, precision and performance. Adorned with extremely refined finishing details, it embodies a perfect blend of avant-garde technology and respect for tradition.

The quest for essentials and the refusal of anything superfluous was also the guiding principle for Blancpain watchmakers in developing the new base Calibre 13R0. The simplest constructions are those that ensure maximum reliability, while also facilitating maintenance. However, in both watchmaking and literature, simplicity is often the culmination of lengthy research.

Blancpain meticulously studied all components of mechanical movements in order to choose the most effective solutions. The result is an efficient, accurate and reliable “motor” that once again takes the art of watchmaking to new heights.

A Regulating Screw System for Enhanced Precision
Blancpain first focused on the sprung balance – the regulating organ of the watch – and on its adjustment system. Most mechanical movements are equipped with a mobile organ named an “index” that enables one to adjust the active length of the balance-spring, and thus the oscillating speed of the balance. Some brands opt for a swan’s neck system with a more decorative appearance. Control of the rate is thus achieved by means of regulating screws placed on the balance rim or felly. Tightening the screws inwards reduces the active diameter of the balance, thereby increasing the speed of the oscillations – and vice versa. This system features several advantages compared with most existing devices. It takes less space than an index or a swan’s neck. The balance maintains concentric oscillations, since no organ presses against one of its ends (which would inevitably modify its shape).

Nor is there any risk that a shock might modify the position of the index or the swan’s neck and thus be detrimental to the rate of the watch. Nonetheless, the supreme advantage is the precision and the effectiveness of the adjustment. There is no need to seek the correct adjustment empirically by small backward or forward pushes.

The regulating screw system enables one to anticipate changes in rate. On Calibre 13R0, a quarter-turn of the two diametrically opposite screws results in a modification of thirty seconds per day. Once the rate of the watch has been verified on a chronoscope, the watchmaker knows exactly by how many fractions of a turn he must tighten or loosen the screws. To facilitate this task, Blancpain has equipped the gold micrometric screws with square heads, which mean the watchmaker can more easily visualise the corrections he is performing.

A Larger Titanium Balance for Improved Rating Regularity
Due consideration was then given to the diameter of the balance. The goal was in particular to achieve the best possible ratio between mass and inertia, thanks to a larger-diameter balance, which accordingly reduces differences in rate between horizontal and vertical positions. In order to optimise rating regularity, Blancpain chose a titanium alloy.

While it is very hard to work with, this avant-garde material features several decisive advantages. It is far less sensitive to variations in temperature than glucydur, which is used in most modern balances. It is anti-magnetic and it is also distinguished by its amazing lightness. The lighter a balance, the less energy is consumed by its to-and-fro motion; the less the force of gravity affects the regularity of its oscillations in its various positions; and the less influence is exercised on its tiny pivot measuring a mere 6.5/100th of a millimetre. Consequently, the balance-spring which serves to compensate for the expansion of the balance had to be adapted to the titanium balance.

A Breguet Overcoil Balance-Spring for Optimal Isochronism
A flat balance-spring on a single plane cannot develop in a perfectly concentric manner. To guarantee the sprung balance a maximum of isochronism (regular oscillations whatever the amplitude), Blancpain has opted for a so-called “Breguet” overcoil balance-spring with the outer coil raised and slightly tilted towards the centre on a plane running parallel to the spring; this astute device enables the balance-spring to maintain its round shape at all times (whether in contraction or expansion phases). Producing a Breguet overcoil balance-spring calls for a great deal of extra work. In the absence of machines capable of producing a correct result, each extremely slim terminal curve must be patiently shaped by hand, an approach requiring considerable experience and incomparable dexterity. Nonetheless, this demanding choice contributes to giving the movement greater rating regularity, and hence improved accuracy.

Three Barrels For an Impressive 8-Day Power Reserve
In developing Calibre 13R0, the Blancpain watchmakers also strove to find the most effective solutions in terms of energy. The main goal was to give the movement optimal operating autonomy, while guaranteeing energy of the finest “quality” at all times. The Calibre 13R0 (in its current hours / minutes / seconds / date version) has an exceptional 8-day power reserve (192 hours). To achieve this feat, Blancpain has equipped it with three series-coupled barrels. Watchmakers made sophisticated calculations to precisely define the size and torque required for each spring. The three springs wind up and wind down in turn, but the second takes over from the first before its strength diminishes, and the same goes for the third. This system guarantees constant energy throughout the duration of the 8-day power reserve. The two springs closest to the winding spring are equipped with slipping springs, an added security feature that avoids any damage to the movement if the springs were to be over wound (by forcing the crown).

A “Bidirectional” Date for Optimal Security
Another technical improvement lies in the fact that the date change at midnight and the fast correction may be done in either direction. On most watches, it is impossible to move the hour and minutes back past midnight, since this might damage the date change mechanism.

On the new Calibre 13R0, the finger piece driving the date disc simply slides backward over the teeth and thus runs no risk of being damaged itself or of impairing the disc.

Decorative Features Worthy of a Noble Tradition
While the construction of the new Calibre 13R0 aims for a maximum of simplicity and efficiency, its finishing details are distinguished by their extreme refinement and their high-end aesthetic appeal. The bridges, which are corrected in classic style, feature elegant cut-outs as well as bevelling that is more noticeable than usual; they are also adorned with a Côtes de Genève motif, a sure sign of a finely crafted movement. All the steel parts are hand-bevelled and drawn out with file strokes. The plates are stippled, while the wheels circular-grained and bevelled. The ratchet and the transmission-wheel boss are decorated with a sunray pattern.

The gaze is immediately caught and held by the large jewels, delicately rimmed in gold. However, out of a concern for simplicity, Blancpain decided not to use seatings to house the jewels. The use of these intermediate parts was fully justified in an era when hole drilling and jewel production techniques were not sufficiently precise to ensure perfect assembly. However, technical progress now makes it possible to drive the jewels directly into the bridges and plates to within infinitely small tolerances. To maintain the visual magic of the jewels sparkling amid the gold, Blancpain has revived the time-honoured “moulding” technique.

The recess around the hole destined to house the jewel is meticulously mirror-polished and then gilded; the double sinks add an original and exclusive touch. The movement design engineers have also devoted particular care to making space in the centre of the movement in order to provide a clear view of the large seconds wheel.

Time for Renewal
The new Calibre 13R0 was first and foremost conceived as a base movement intended to accommodate various complication modules. This perspective will oblige Blancpain to rework all the famous complication “plates” that have contributed to forging its reputation. This movement is also intended to evolve towards a self-winding version. Calibre 13R0 and its future developments should therefore herald a significant renewal in the Blancpain movement collections, representing a further step towards precision, reliability and performance.

Technical details
Ref. 4213-3442-55B
Le BRASSUS, “8 Jours”
Date and seconds-hand, indication of the power-reserve, opaline dial, hand-winding.
Edition: limited to 260 pieces

Case
Platinum Case
Diameter: 42 mm
Thickness: 12.09 mm
Between horns:  22 mm
Sapphire crystal case back
Water resistance: 100 m

Movement
Calibre 13R0
Total diameter:  13.5 lines (30.60 mm)
Thickness:  4.57 mm
Number of jewels:  30
Number of parts:  211
Frequency:  28,800 vibrations/hour (4 Hz)
Balance:  titanium, with adjustable screws
Balance-spring:  Breguet overcoil
Power reserve:  8 days (192 hours)

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