Feature: Grand Seiko Spring Drive

When entering the realm of watchmaking, the first thing a curious novice will discover is that watches don’t all tick. Some do, and those are mainly quartz, but many don’t—they sweep, in a fine, jittery motion, and these are mechanical movements. Quartz is accurate, our novice learns, but mechanical has soul, history and craftsmanship. But there’s another type of movement, one that glides smoothly without a tick or a jitter, as accurate as quartz but with all the hallmarks of mechanical—could it be the best of both worlds?

Seiko, as the general populace knows it, makes watches. But Seiko isn’t just one company, it’s three, Seiko Holdings Corporation, Seiko Instruments Incorporated and Seiko Epson Corporation. Seiko doesn’t just make watches, it also dabbles in stuff like, oh, semiconductors, micromechatronics and nanotechnology. What may have started off in the latter part of the 19th century as a watchmaking firm diversified rapidly in the wake of the electronic age, embracing the future in a way that changed watchmaking forever.

It was on a cold December day in 1969 that Seiko made a move that turned the tide on Swiss dominance, announcing an electronic watch regulated by a quartz crystal. It was housed in a gold case, a limited edition of just 100 that cost as much as a car, and it marked the end of an era. By 1977, in the wake of a decimated Swiss mechanical watch industry, Seiko had become the largest watchmaker in the world.

To fully appreciate the tumultuousness of Seiko’s dominance, it pays to dig a little deeper into the extents the company went to realise its vision for the future. Since it began, Seiko’s focus was always precision, with Grand Seiko developed as a benchmark to challenge its brightest minds to make the best watches in the world, to beat the Swiss at their own game. Good enough was never good enough, and so development after development followed in quick succession, with the accuracy of its mechanical movements reaching the pinnacle of one minute per month—a result that topped the 1968 Geneva observatory chronometer competition.

With mechanical precision mastered, it was to the quartz calibre in the Astron that Grand Seiko turned its attention next. As a first attempt, its accuracy showed promise, running within just five seconds per day; with the Grand Seiko touch, the possibilities were boundless. So, Seiko invested heavily in electronics, retooled its factories, retrained its staff, even learned how to grow its own quartz crystals—and the result was the calibre 95GS, a movement accurate to ten seconds every year.

It was the quartz movement that rocketed Seiko to the top, but the company hadn’t abandoned the mechanical movement entirely. After 28 years of development, starting way back in 1977 at the Seiko skunkworks under the watch of engineer Yoshikazu Akahane, the beauty of mechanical and the accuracy of quartz were fused into one for the 1999 Grand Seiko Spring Drive.

It took over 600 prototypes, 230 patents and countless manhours—many spent of an evening in Akahane’s own home—to develop the Spring Drive, an idea that first came about in the quest to achieve a self-regulating quartz watch. Hampered by technological progress again and again, revisiting the project with every advancement, Akahane finally saw his work completed after almost three decades—but sadly passed away that same year.

But what exactly was his legacy? Many people assume that Spring Drive is merely a mechanically charged battery—like the alternator in a car—that runs a typical quartz movement, but this could not be further from the truth. A Spring Drive watch derives its power from a mechanical source and regulates it with a quartz crystal, but here is where the similarities end.

So let’s start at the start: Spring Drive, be it manual or automatic—like this calibre 9R86—has a mainspring, just like a mechanical movement. That mainspring is connected to a series of gears that drive the hands, just like a mechanical movement. All straightforward so far. But, like a mechanical movement, this arrangement on its own isn’t good enough; what’s to stop the mainspring unwinding in one explosive go? In a mechanical watch, that’s where the escapement comes in, a feed from the gear train that locks and unlocks the driving wheels to allow the power to escape in stuttering bursts.

Not so with the Spring Drive. In the path of gears that makes its way from the mainspring to the hands is a component called the glide wheel, whose revolution within a stator—a wire coiled 25,000 times—generates a small electrical current, just like the dynamo on bicycle light. This current vibrates a quartz crystal, from which the timing is derived.

But how is that vibration converted into mechanical regulation? A quartz watch simply converts it into a signal that tells the motor driving the hands when to start and when to stop, but there’s nothing like that here. Instead, the same current created by the glide wheel is used to power an electromagnet that acts like a brake to stop it from spinning out of control. The most impressive part is that it’s completely contactless and free-running, making wear virtually non-existent. And it also has a rather pleasing side-effect: the second hand doesn’t tick, or jitter—it’s sweep is completely smooth.

Understanding the Spring Drive movement sheds light on why it took Seiko 28 years to develop. To produce components with the precision and efficiency to give every Grand Seiko with it fitted an accuracy of a second per day and a power reserve of at least 72 hours required an immense amount of research and technical know-how. Not something any typical watchmaker could achieve, but when you own the companies that develop the technology in the first place, anything’s possible.

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