Grand Seiko’s Pursuit of Precision

In a very fundamental sense, Grand Seiko is really all about precision. The first Grand Seiko watches from the 1960s were designed to be, as much as their creators could make them, perfect daily wear timepieces — time only, or time and date, but with strongly built, high precision movements with long power reserves, and close attention to detail in every aspect of the watches. As time went by, Grand Seiko watches became more and more accurate, and precision at Seiko began to compete with, then match, and then overtake the precision of Swiss mechanical movements, to the point that at the 1968 observatory competition at Neuchâtel, Seiko set a world’s precision record, leading to the competition being shut down the next year.  

The pinnacle of the first generation of Grand Seiko accuracy were the VFA, or Very Fine Adjusted, mechanical Grand Seikos, which were made from 1970 to 1975, and which were adjusted to a variation in rate of just ± 2 seconds per day, or a minute a month. 

Grand Seiko was reintroduced with high precision quartz movements in 1988, and the first mechanical Grand Seiko watches of the new generation were launched ten years later. And, in 2004, the first Spring Drive watches were shown — a new generation of high accuracy hybrid quartz mechanical watches. 

Grand Seiko has continued to pursue innovations in precision ever since, and three of its most important technical advances have been in the escapement, the tourbillon, and this year, in Spring Drive. 

The escapement is the most fundamental component of any mechanical watch, and, indeed, any mechanical timepiece of any kind at all, whether clock or watch; without the escapement, mechanical horology could not exist. It’s the escapement which allows the energy stored in a watch mainspring to be released in identical measured increments, converting the rotational movement of the gear train into the back-and-forth oscillations of the balance. The balance controls the rate at which energy is released, and therefore, the speed at which the hands advance, telling the time. 

For much of the history of watchmaking, only a single escapement has been used in watches. This is the lever escapement, which is first known to have been used by the English horologist Thomas Mudge, in 1755. The escapement in almost any modern watch is a lever escapement, with few exceptions (the co-axial escapement is one of the rare examples of a non-lever escapement in industrial production). The lever escapement has many advantages; it is shock tolerant, and for most of its action cycle, it is not in contact with the balance, allowing the latter to oscillate freely. However, it also delivers energy indirectly and is therefore less efficient than an escapement would be that delivers energy directly from the gear train to the balance. 

Grand Seiko launched a new version of the lever escapement in 2020, which goes a long way towards addressing this. The new escapement is the Grand Seiko Dual Impulse escapement. The Dual Impulse escapement was launched in the Hi-Beat caliber 9SA5, running at 36,000 vph, and it has a unique design, in which impulse is given indirectly, by the escapement lever, in one direction and directly, via the escape wheel, in the other (although there are differences, this is essentially the same solution to be found in the co-axial escapement). This means an increase in efficiency, and also a reduction in the amount of friction on the impulse surfaces — an incremental, but significant, improvement over the classic lever escapement.  

Grand Seiko has also produced a highly complicated mechanism designed to advance the art of the tourbillon. This mechanism is a new type of constant force device, known as a remontoir. The remontoir is essentially a secondary mainspring, placed in between the escapement and the primary mainspring, which is periodically wound up by the gear train, and which releases energy in equal amounts and at regular intervals to the escapement. As long as the primary mainspring has enough energy to wind the remontoir spring, the escapement and balance wheel will receive precisely the same amount of energy throughout the power reserve of the watch, improving timekeeping. 

The Grand Seiko Kodo Tourbillon combines the tourbillon and remontoir in a very unusual way. The two are not often found together in the same watch — F.P. Journe was the first to do so in a wristwatch, although he was preceded by the English watchmaker Derek Pratt, who invented a remontoir — in a pocket watch — which is actually inside the tourbillon cage. The Kodo Tourbillon is unlike any preceding tourbillon with remontoir, however. It consists of two nested cages, with the remontoir on the outer cage, and with the inner cage being the tourbillon proper. The outer remontoir cage advances once per second as it discharges energy to the spiral remontoir spring under the tourbillon carriage, which drives the tourbillon proper. Since the escapement beats at 4Hz, and the remontoir “ticks” once per second, the two together produce a unique auditory and visual experience — all this in a watch that combines a solution to the problem of variation in rates in positions (the tourbillon) with a solution to the problem of consistent power delivery (the remontoir).  

And then, there’s the UFA Grand Seiko, with caliber 9RB2. This was one of the most talked about advances from Grand Seiko in some time, and a welcome advance in the state of the art of Spring Drive. UFA here stands for Ultra Fine Accuracy, and the new UFA Grand Seiko has a precision of ± 20 seconds per year — a dramatic change from the previous ± 1 second per day. Spring Drive is a unique timekeeping system, in which a mainspring powers a magnetically braked generator whose speed of rotation is controlled by a quartz timing package. Significantly, there is no battery.  

Grand Seiko achieved this increase in precision through a series of incremental improvements — for example, the quartz crystal used in the timing package is pre-aged for three months before its installation, in order to let it settle down on its rate, and temperature compensation is built into the system as well, since quartz crystals actually vary on their rate if the temperature changes. The temperature drift of each crystal is measured, and programmed into the timing circuit, and the movement has a rate trimmer which allows any long-term drift to be corrected.  

These three advances in precision take place across an impressively varied range of watchmaking systems and technologies. And they represent something just as impressive as their specific achievements: the ongoing dedication to precision that’s the essence of Grand Seiko.