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Caliber 9S85


Caliber 9S85

The challenge of making a high-beat movement is one that only a few watchmakers choose to accept. With its higher oscillation rate of ten beats per second, greater accuracy is achievable, but this increased precision comes at a price because the faster rotational speed can take its toll on the power reserve and even the longevity of the whole movement. Grand Seiko's 10 beat movement meets these challenges and delivers an accuracy of +x to –X seconds a day, a power reserve of xx hours and the durability for which every Grand Seiko watch is renowned. Caliber 9S85 is the result of many years of development and of advances both in the design and manufacture of components and in the materials themselves.

Driving system Automatic with manual winding mechanism
Accuracy +5 to -3 seconds per day (under a static use)

Note: This accuracy is the result of measuring the loss/gain of the time for seventeen days before the inside movements of the watch are put in the case. The measurement has been done in the factory where temperatures or position of the movements are controlled.

Actually worn from +8 second/day to -1 seconds/day
Power reserve Approximately 55 hours
Vibrations 36,000 vibrations per hour (10 beats per second)
Jewels 37 jewels

The challenge of the 10 beat movement

Although the theoretical advantages of the 10 beat movement are well known, to produce a watch that is durable, reliable and precise is extremely difficult. The two main difficulties are driving time and movement durability. A rapidly oscillating balance wheel requires a lot of power from the mainspring. The mainspring must be able to supply the balance wheel with the energy it needs to move back and forth at high speed. The wound mainspring has to be able to deliver a high level of torque to be able to supply enough power to the balance wheel for long enough to ensure a high power reserve. At the same time, the escapement mechanism that transfers the oscillations from the balance wheel through to the gear wheel train has to be as durable as any other mechanical watch. A formidable challenge indeed.


New materials to enhance fundamental performance

Using the experience accumulated over the 50 years of Grand Seiko’s history, a new generation of Spron alloys was developed for the hair spring, which is at the very heart of any watch movement and whose performance determines the precision of the watch over time.
After some five years of development, a new alloy, Spron 610 was created. Compared with previous alloys, Spron 610 had around twice the impact resistance, and a magnetic resistance more than three times higher. In addition, the new alloy completely delivered much higher torque at high oscillation frequencies, enabling the watch to maintain a constant level of accuracy in actual use.


MEMS technology to enhance component precision

Precision engineering is the route to greater accuracy in every watch, but most of all in a high beat caliber. Thanks to technologies developed in-house for semiconductor manufacturing, the escape wheel and pallet fork used in Caliber 9S85 are made with a precision of one ten thousandth of a millimeter and therefore deliver greatly enhanced performance. The secret is MEMS. MEMS (Micro Electro Mechanical System) is a technology that allows these critical components to be lighter, smoother and, in the case of the escape wheel of a more intricate THE ESCAPEMENT MECHANISM design. The new design of the escape wheel featured oil reservoirs at the end of each gear tooth, improving the retention of oil, on which the smooth working of the gear depends.


Increased torque for high-speed oscillation and a longer power reserve

A 10 beat movement must have a mainspring that can ensure a high level of torque to supply the power required for the increased oscillating rate. After six years of development a new alloy, Spron 530, was developed for the mainspring. It delivers 6% more power than its predecessor and a power reserve of five more hours while maintaining the same degree of corrosion resistance, durability, and magnetic resistance. The new mainspring powers the Grand Seiko 10 beat movement for a remarkable 55 hours when fully wound.

What makes 9S special?

Every one of the 200 or more components in a mechanical watch are critical to its performance and durability but none more so than those that make up the regulator and escapement mechanisms.
When the 9S caliber was designed, these were engineered anew. With the subsequent creation of the 9S85 Hi-beat caliber, new materials and new manufacturing techniques were used, further enhancing the performance of these key parts and these latest materials and techniques are now incorporated in all 9S movements, greatly increasing both their power reserve and their precision.

Several of these high-precision components are manufactured to an accuracy of one thousand of a millimeter. Such precision and the use of MEMS manufacturing for the pallet fork and escape wheel make a vital contribution to what makes Grand Seiko’s 9S calibers special, but these remarkable achievements count for little without the skill of Grand Seiko’s craftsmen and women to realize the lasting performance for which Grand Seiko is renowned. Their ability to assemble and adjust each 9S watch is the final, crucial element. Only when their work, and the 17 day testing program to which each watch is subjected, is over can the stringent ‘New GS’ standard be met and the watch’s Grand Seiko certificate issued.
Precision, craftsmanship and innovation all play their part, but, in the final analysis, what makes the 9S family of mechanical movements so special is that all stages, from the design of the movement and parts manufacture to assembly and adjustment are carried out in-house by Grand Seiko’s own watchmakers. For over 60 years, it’s been the same. It’s our people that make the 9S special.