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The Amazing History & Functionality Of The Seiko Spring Drive Movement

The Amazing History & Functionality Of The Seiko Spring Drive Movement Featured Articles

This brief history of the Seiko Spring Drive movement is a segment I originally researched and wrote for my upcoming review of the Grand Seiko Spring Drive Chronograph SBGC001. The review of the watch we will be publishing tomorrow (that is, on Monday, just after midnight, PST), but since this segment turned out to be detailed enough, we figured it would be best to make it into a separate article that was easy for you to find and easy for us to reference later on.

The Seiko Spring Drive watch movement technology is one of the most unique, ingenious, efficient, and accurate calibers ever designed and is in a class of its own among modern mass produced movements. We have covered Spring Drive watches dozens of times here on aBlogtoWatch, so check this link for Spring Drive watch reviews, hands-on articles, and more.

The Amazing History & Functionality Of The Seiko Spring Drive Movement Featured Articles

9R86 Spring Drive Chronograph movement details. Photo: David Bredan

Please note that we will begin with looking at how Spring Drive works for the simple reason that we need a good understanding of how the system functions and is constructed before we can talk about the fascinating story behind it all. As such, we are discussing the history of Spring Drive on Page 2, but first, let us dive into the depths of this magnificent movement…

…But before we do that, humor me a short paragraph’s glimpse into the research required for this article (and a heads-up to Seiko corporate): unfortunately, Seiko is notorious among aBlogtoWatch team members for purposely or unintentionally (we don’t know yet) scattering bits and pieces of valuable information on one single topic between as many online sites, outlets, and media formats as humanly possible. From near-impossible-to-find YouTube videos through random Japanese-only micro-sites to never publicly published PDFs, precious little droplets of information and official images on the same Seiko-related topic lay unorganized in the vast fields of the interweb. It took me a few days to put together this segment below so I hope you will appreciate the effort and feel free to chime in in the comments section with relevant data we might have missed.

The Amazing History & Functionality Of The Seiko Spring Drive Movement Featured Articles

A sexy block diagram of the Spring Drive mechanism. Source: Seiko

How Spring Drive Works

We have talked about how the Seiko Spring Drive works more than a few times here on aBlogtoWatch, but for the aforementioned reasons, we must clarify once again. While a traditional electronic watch is powered by a battery and features a quartz oscillator that controls a step-motor linked to the hands, the Spring Drive movement, as its name implies, receives all the energy it ever needs for functioning from a wound spring.

As such, Spring Drive watches have a mainspring with a power reserve of between two and eight days (depending on the movement) just like a regular mechanical watch. Consequently, their mainspring is connected to a gear train, also very similar to the gear train you would find in a traditional mechanical watch movement. In fact, some 80% of the components in a Spring Drive caliber are the same as those in a luxury mechanical watch.

The Amazing History & Functionality Of The Seiko Spring Drive Movement Featured Articles

Spring Drive watch movement layout. Source: Seiko

The trick, however, is that at the end of this gear train there is a wheel that is not turning back and forth like a balance wheel does in a traditional mechanical movement but is instead turning continuously in one direction. Bear in mind that Seiko calls this wheel a “rotor” because it rotates in just one direction. We’ll try our best to keep things consistent and easy to understand so that you can easily tell when we are talking about the automatic rotor or the rotor responsible for timekeeping, located at the end of the gear train. Check the image above to see the rotor at the end of the gear train.

The question – and the genius – of the Spring Drive system is how accurate time is being kept. In a mechanical watch, it is the escapement and the balance wheel that are responsible for tick-tocking at a set frequency (usually between 2.5-5 Hertz). In the Spring Drive system, what you have is a so-called Tri-Synchro regulator, named for its ability to control three different types of power:

  1. Mechanical power (mainspring)
  2. Electric power (integrated chip, or “IC”; quartz oscillator)
  3. Electromagnetic power (rotor; stator)

The Amazing History & Functionality Of The Seiko Spring Drive Movement Featured Articles

The Tri-Synchro regulator controls and coordinates each of these three power sources, and the way it functions is just inspired.

If there is no battery, how are the quartz oscillator and integrated circuit powered? …you may rightfully want to ask. Well, the rotor, together with its coil blocks acts as a power generator. It works in the same way as a bicycle dynamo that generates electricity from a rotating wheel.

The Amazing History & Functionality Of The Seiko Spring Drive Movement Featured Articles

The generated electricity activates the Integrated Chip (IC) and the quartz oscillator linked to it, with the latter generating a precise reference signal of 32,786 Hertz. The chip compares this signal to the rotating speed of the rotor, which is eight turns per second. How all this came to be, we’ll look at on Page 2, but for now, we keep on moving.

The Amazing History & Functionality Of The Seiko Spring Drive Movement Featured Articles

Magnetic power is used for breaking/regulating the speed of the rotor for excellent timekeeping.

Now that we have the necessary electric power and a reference signal to run the watch by, the last task at hand is to ensure that the rotor, the gear train, and hence the watch’s hands rotate at the exact speed we want them to. For this, the Tri-Synchro regulator periodically applies an electromagnetic brake to ensure that the rotor’s rotation is aligned with the reference signal from the quartz oscillator. The IC monitor compares the rotor’s speed with the signal and intermittently applies this magnetic brake to prevent excessively fast rotation…

…And that is how Spring Drive works. Driven by a wound mainspring through a regular gear train and regulated by an integrated circuit and quartz oscillator, it is a most unique blend of traditional mechanical watchmaking and 21st-century technology.

The Amazing History & Functionality Of The Seiko Spring Drive Movement Featured Articles

416 parts, 50 jewels, 140 oil points and 5 different lubricants. The 9R86 Seiko Spring Drive Chronograph movement.

Now, at last, let’s imagine all this electro-mechanical, mainspring-driven technology shoehorned into a case small enough to be perfectly wearable on the wrist, have three days of power reserve, be accurate to no more than +/-15 seconds per month, and be reliable in the long run at a much wider spectrum of temperatures than regular mechanical watches.

The Amazing History & Functionality Of The Seiko Spring Drive Movement Featured Articles

By the way, as for long-term reliability, Seiko says that because the entire gear train rotates constantly without several stops every moment, because there is no traditional escapement with sensitive, lubricated sections, and the rotor wheel of the gear train rotates continuously, Spring Drive movements should last you a very long time. As for the electronic parts, because there are no chemical components (e.g., a battery) to deteriorate and the way the electronics work are comparable to quartz movements (which can last several decades), one should expect long life from a Spring Drive watch.

All this noted, let’s get to know the man behind the remarkable idea of Spring Drive and learn about the thirty-year-long progress it took Seiko to bring Spring Drive to the world. It is also here where we’ll have the chance to find out more about the technical details of Spring Drive and go beyond the mere principles of its functioning.

About the Author

David Bredan (abtw_david) is a young watch enthusiast based in Budapest, Hungary. He is dedicated to understanding, revealing and discussing as many aspects of fine watch making as possible. Fascinated by the countless admirable details of haute horlogerie, he strives to discover the challenges linked to the manufacturing of fine timepieces and also those related to chronometrical performance. As much as he loves unfolding the mysteries of mechanical timepieces, he also aspires to successfully capture and share the nuances that separate a fine watch and a masterpiece.


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  • Thanks for the detailed article David. What I’ve always found fascinating about Spring Dive is the innovative use of the electromagnetic feedback so that the brake uses virtually no more power than is generated against it. Such a clever system from a power consumption standpoint. The more the going train tries to push against the brake, the more power the brake has to slow things back down. Quartz regulation, done before. Spring powered watches, done before. Electric/quartz watches without batteries, done before. But the brake system is the magic that makes Spring Drive so unique.

    • David Bredan

      Very well said, Mark. I’d only add that it’s both the brake and the power efficiency of the system that makes it so special – 25 nano watts is an almost impossibly low amount. The inspired genius is in the braking system, the decades long engineering struggle is in making it all work and bringing it into mass production.

  • That chronograph movement breakdown is INSANE!

  • Svetoslav Popov

    It is similar to an electric car that draws power from batteries to compress air, which is then used to drive a piston engine 🙂 I know that it was a technological feat to implement Spring Drive, but I really find it extremely superfluous. If coils and chips are to be involved, I prefer pure quartz movements. Simple, reliable and more precise.

    • I get where you are coming from. I think the pull of spring drive is not the superior accuracy but the compromise between Quartz-regulated accuracy and the visual charm and aesthetic of a mechanical movement. GS and FPJ have done very well to make a “pure Quartz” movement look sexy, but the SD glide wheeeeeeeel….

      • Svetoslav Popov

        Just in my head mechanical and coils and chips do not play together 🙂

  • Love the spring drive. The Credor Eichi II with reserve indicator on the movement side is the perfect intersection of the tech and pure watchmaking IMO.

    • IanE

      Quite agree! I’ve been very resistant to SD and have taken some time to come round – finally yielding after seeing one in action: that so-smooth movement is so unique and irresistible that my ‘purist’ instincts have been undermined. Now that I have quartz, straight mechanical and a true-beat, I find that I ‘need’ an SD (Snowflake on order : Eichi II out of range, sob). Resistance really is futile!

      • You are right on the path Ian. What are the respective models if you don’t mind me asking?

        • IanE

          Two Seiko quartz beaters, a Botta Uno 24 (my fun single-hander for my Zen moods) and a Casio Protrek 2500.
          3 Omegas (Seamaster 300M Ceramic blue, Speedmaster sapphire sandwich [not for the purists – but I love it!], and an Aqua Terra GMT Goodplanet); 2 JLCs (MUT Moon black dial and Geophysic Universal Time – the True Beat, of course);
          Breguet 7027ba, La Tradition Yellow Gold;
          ALS 1815 up/down.
          I really thought I was ‘there’ after that lot, but my greed has taken off again and I think the Snowflake Spring Drive may finally sate me!?

          • Killer line up! Yes I dare say you have a small snowflake-shaped gap in that great collection.

  • Word Merchant

    I love the idea of the Spring Drive but the aesthetics of Seiko watches jar my sensibilities every time. For every beautifully finished hand set and pristine hour markers there’s a underwhelming strap or a poorly executed and places power reserve or some grim gothic text. Often together.

    I’d love to own another Seiko – I had a Time Tide quartz a long time ago, I lusted after a ‘Pogue’ when I was a kid, and I seem to remember a lovely art-deco styled Spring Drive moon phase watch, but I can’t pull the trigger.

  • BenC

    Any prospect of a thermocompensated Spring Drive?

    • rpste

      I think Seiko can do it. 5-10s/year accuracy with Spring Drive is not impossible with their capabilities from Epson, SII, and the smaller companies. Just reminder Seiko has collaboration with Tohoku university for development of SPRON
      This MM600 owner is the most luckiest owner, the movement itself better than 9F (GS quartz)

      • David Bredan

        As I’ll mention in tomorrow’s Spring Drive chronograph review, Seiko has one-upped their 9R86 movement with the more recently released 9R96. It is essentially the exact same movement just with an even more carefully selected quartz oscillator that brings accuracy to +/-10 seconds a month or 0.5 seconds a day. That is incredibly accurate. SBGC013 in titanium and the new ceramic SD chronographs watches feature this updated movement.

        • But the question remains, is that level of accuracy maintained under various ambient temperatures? Hence the question about themo-compensation.

        • BenC

          The better crystals more closely match the reference frequency at the reference temperature, but still expand and contract outside that reference temperature. This thermal expansion affects their vibration.

          According to Wikipedia, for a 32 kHz quartz oscillator, a 10 Celsius degree difference will cause the rate to deviate by roughly 10 seconds per month.

          As 10 Celsius degrees is the difference between wearing a watch and storing it in a cool place, 10 sec/month is about the limit for uncompensated 32khz quartz, even using a ‘perfect’ crystal.

          Seiko SD can use a higher frequency crystal and/or add circuits to measure the temperature and adjust the count. This will require more power unless the components involved are further miniaturized.

          I was hoping for news if Seiko might be working on that, as OCD-level accuracy is one area where Citizen’s competing product has an advantage. I prefer the Seiko aesthetics though.

          My personal SD gains 15 seconds a month, worn 15 hours a day and otherwise stored in a drawer with ambient 25degC temperature, as I live in the tropics.

          A ‘fast’ watch is of course easier to correct than a slow one. I synch mine to every time the date needs correction.

  • SuperStrapper

    Will never understand anyone not interested in this technology.

  • IG

    I hate automatics, I hate quartz, I double hate this.

    • SuperStrapper


  • Arthur Davis

    How long would the movement last before it needed servicing, and how expensive would that be (ballpark)?

    • Marius

      According to Seiko, a Grand Seiko Spring Drive should be serviced once every three years to improve its longevity.

      A good friend of mine owned two GS Spring Drives, and this is how much the service cost him:
      – A simple time only + power reserve cost him $600 + approx. $200 for polishing the case & bracelet.
      – A Chronograph will cost you $900 + $200 for polishing the case & bracelet.

      The problem, however, is that Spring Drive watches are usually (99% of the cases) send to Japan for service. This means that the waiting time can be quite long. For instance, my friend sold his GS Spring Drive Chronograph precisely because of the very long servicing intervals — one time he had to wait 8 months to get the watch serviced.

      • IG

        It takes 1 year to make a Rolex, so it can take 8 months to service a Seiko, right? Patience is the key.

      • IanE

        Sounds like Patek Philippe!

        • Marius

          Actually, servicing a Patek is much cheaper than most would imagine. It’s certainly cheaper than servicing a Rolex or an Omega. Here is the pricelist:

          Maximum Public Price without tax (Expressed in CHF Swiss Francs)

          Battery change 130
          Quartz (Level 2) 550
          Mechanical (Level 2) 700
          Automatic (Level 2) 800
          Complication I (Level 3) Annual Calendar, Travel Time, moon phase, etc. 1050
          Complication II (Advanced Level) Perpetual Calendar, Chronographe, Chronographe Annual Calendar 1500
          Complication III (Advanced Level) Chronographe Perpetual Calendar, Perpetual Calendar Retrograde 2000
          Grand Complication (Advanced Level Geneva) tourbillon, split-seconds chronograph, retrograde, minute repeater, etc. estimate
          Classic collection (more than 20 years old) estimate
          Objects estimate
          Refused estimates 130

    • David Bredan

      The 9R86 chronograph movement (see exploded view above in the article) has 416 parts, 50 jewels, 140 oil points and requires the use of 5 different lubricants – so it is strongly advised you send it back to Seiko.
      Here’s Seiko’s official wording:
      “The movement of this watch has a structure that consistent pressure is applied on its power-transmitting wheels. To ensure these parts work together properly, periodic inspection including cleaning of parts and movement, oiling, adjustment of accuracy, functional check and replacement of worn parts is needed. Inspection and adjustment by disassembly and cleaning (overhaul) within 3 to 4 years from the date of purchase is highly recommended for long-time use of your watch.” To get a quote I’d suggest reaching out to your local Seiko AD, though what @disqus_sIZFPdTyFw:disqus quoted sounds about right (if not a bit high, but then again, there may be differences based on your location, etc).

      • “…pressure is applied on its power-transmitting wheels” is also true for the going train of a conventional mechanical watch.

    • Michael von Bornemann

      A lot less than a normal mechanical watch – there’s no escapement momentarily locking up all the torque of the mainspring 5 to 10 times a second (depending on the movts beat), which puts sidways force on the bearings of the whole gear-train between the mainspring & the balance, maximising friction. Instead the equivalent of a balance is being slowed by electromagneticism, turning it into a generator. In fact I doubt the spring drive movt needs more than a couple of jewels, if that, the rest of the jewels are basically about minimising friction to maximise power reserve & MARKETING.

      Seiko recommending a service every 3 to 4 years is just about milking people who can afford to pay about 5 grand or more for a watch.

  • Omegaboy

    One thing that puzzles me is that the ‘brake’ periodically goes into action, which assumes that the watch is running fast. What if it’s running slow? How does it compensate for that?

    • rpste

      Maybe if the brake is too strong (probably magnetized? but I can’t find an owner have SD running so slow). I think the IC part just have logic “brake it 8x/s to make it under speed limit), and no need to compesate even when the IC always trying to brakes 8x/s, and impossible to running slow (if the watches is still under good condition)

    • The mainspring tension and gearing is such that it wouldn’t run slow without the brakes during its autonomy. The brakes are vital to the timekeeping but they are not perfect, hence the watch can still run at a slow or fast rate deviation.

    • David Bredan

      My understanding is: this being a “uni-directional” gear train, meaning the rotor itself spins in just one rotation, it is impossible for it to run slow (until the last moment of the power reserve). If it wasn’t being slowed down constantly, the mainspring would suddenly unwind, spin all gears very fast and offer a power reserve of 20 seconds, not 3 days. This is to say that there is no need to add speed, it’s just about regulating/slowing that quick unwinding to a point where it results in accurate timekeeping and balancing that rotation with fine adjustments to compensate for different effects (temperature, torque, etc.). Hope this clarifies.

      • Omegaboy

        Thanks, clear, short ‘n sweet explanation.

    • There is a calculation on how fast the final stages of the gear train will spin, according to the input torque. It involves all the gear ratios, and losses thru friction in the gears themselves and in the bearings holding them, among other variables. The resulting maximum speed and acceleration at the regulator point will be known with some degree of accuracy +/- a tolerance resulting from manufacturing processes ( that’s why they use highly polished gears as they have less friction and will get “worn” less resulting in both less power loss and longer life). All they have to do then is to design the train and the power in a way giving the movement controllable characteristics, more precisely a maximum speed superior to the one needed and an acceleration rate that can be easily controlled by an eletronic quartz feedback loop. Optimizing this to the degree it was in order to make a wrist watch feasible is a great engineering feat. Seiko deserves full kudos for this movement.

      • Omegaboy

        Shazam. ??? See David’s response below.

        • It’s the same answer, just worded differently. The un-braked movement would always run way fast, so the brakes are always necessary to slow – it’s the extent to which the brakes are used that results in accurate timekeeping over the autonomy of the movement.

        • I’m not entirely sure why you seem puzzled Omegaboy. Imagine how fast those gears should spin in order to exhaust 72h of power reserve in 20 seconds. About 13000 times faster than normal. I believe the acceleration needed to reach that terminal speed so the power is exhausted that quickly, would probaby destroy the delicate movement. Imagine the generator side of the movement fails so there’s no control anymore. Total mess.

          • David Bredan

            Obviously, that 20 second remark was to give you an idea and not based on gear ratio calculations. Naturally, sudden unwinding does not happen, but then again, the original question was not about that but about the lack of a need for acceleration – which I have answered.

            Also, notably, what I found (not a scientific experiment, just observing) was that if you let the system run down and then restart it, the rotor spins faster for a short period of time (few seconds), generates a charge which in turn starts to regulate it – needless to say, this is not written down anywhere by Seiko, just what I saw once as I was fiddling with the watch (so, unlike everything in the article above, this I couldn’t fact check and hence left it out).

          • The lack of need for speeding up is from calculation. The movement is specifically designed to run in a way that can be controlled by low power braking. Interesting the observation about the watch running faster when started. As with any electronics there’s a current inrush in the voltage regulating side of the controls, as the capacitive loads inside reach their nominal charge. The higher speed you’re seeing in the first few seconds is probably close to the maximum the movement is designed to run at if unregulated.

  • This is classic high end watchmaking with a Japanese twist. A Spring Drive Grand Seiko is one of my grail watches.

  • Richard Baptist

    I love the spring drive movement. I think this sort of innovation would only come out of Japan. They always seem to try different technologies and push boundaries when it comes to watch making. A spring drive is definitely on the bucket list.

  • Ibrahim Akinci

    The best watch related article I read in a long time. Thank you for your efforts David

    • David Bredan

      Wow! Thank you.

  • Yan Fin

    David, thanks a lot for a really good article! Informative, interesting, and to the point. As to the watch itself- service part would be the breaking point for me. Also, the durability in between the services seems pretty questionable. Plus, aesthetically completely not my cup of tea. I would go with some auto diver, and solar Chrono instead (if I have to)

    • Beefalope

      I’ve owned and still own several Spring Drive watches. I’ve never had any issues with them. Typical Seiko reliability.

  • Evgeniy Lagutkin

    Wow, just wow…that’s technology!

  • Yikes! “Spring Drive movements should last you a very long time” as long as you spend $300 a month for service!

    • Phil Ormsby


    • Beefalope

      Double huh?

      • David Bredan

        Make it a triple. 🙂

      • If you service it every three years as recommended, and it costs $900, that sounds like $300 a year you have to save for basic maintenance. Forget having to ship it to Japan.

        • Beefalope

          That’s $300 a year for service, not $300 a month as you previously wrote.

          That recommended service interval is not particularly different from most other mechanical watches, which also typically have three-year service intervals.

          Spring Drive watches can be serviced at their service center in New Jersey, but they don’t do Zaratsu finishing anywhere but Japan. So if you wanted to have the full re-finishing done on the case and bracelet, the watch would have to go back to Japan. Again, though, I don’t think that’s too different from other mechanical watches. I’m guessing you wouldn’t want your local service center doing a full re-finishing on an Omega or Rolex, for example.

          Also, bear in mind that the recommended service interval for a Spring Drive is to ensure maximum accuracy. My experience with all Seikos has been that you wear them for year and years without servicing and be just fine as long as you’re more willing to tolerate a decline in accuracy. Again, the same is true of many other watches.

          • Well…nuts. Did I say month? Of course you’re right.

          • Beefalope

            None of us — except perhaps the folks at Credor or Lange — are perfect. 🙂

  • spiceballs

    Great writeup David and I look forward to reading your followup. Certainly clarifies the SD action for me. Thank you.

    • David Bredan

      So glad to hear that, thanks for your kind words!

  • Yojimbo

    if the posts were all like this, I would have zero complaint ever

  • n,kazuya

    Picture No.4 is not Spring Drive watch movement layout.
    this is just quartz movement.

  • BenC

    Any stats on the relative efficiency? Meaning, with the same mainspring, how many hours of power could a rival mechanical watch offer?

    I guess a rough answer is “30% better than 5hz” since the hi-beat GS watches offer about 52 hours of power reserve. However I am not certain they are using the exact same mainspring.

    A more interesting comparison would be to something like the Vacheron 5100 movement (4hz, 60 hours from single barrel) on the VC Overseas ‘simple date.’ If VC had the exact same SPRON mainspring, same length etc, how many hours would its power reserve be?

    After all, if the conpetitor isn’t at least double the price of the Seiko, it’s not a fair comparison is it? 😉

  • Beefalope

    I love Spring Drive watches for many reasons, but my fondness for them primarily comes down to that awesome seconds hand and an appreciation for the remarkable engineering behind the movement.

  • Der0

    Amazing article.

    Great detail and explained simply. Very well done.

    Spring Drive is undeniably the most leap and bounds forward thinking of watch movements to come out in watchmaking. None of this oscillation still bound in escapement. Anchor Escapement, Co-Axial Escapement… none of it matters because it’s just simply taking the whole escapement component away altogether!

  • Polerouter

    Very cool article. There is one important piece of information missing however. There is a swiss patent from the 70s which describes exactly the same concept, and it seems that the swiss and the japanese came uè with the same idea at approximately the same time. Years later, a swiss lab named Asulab (belonging to the Swatch Group) developed a fully functional watch which you can see in the horological museum of La Chaux de Fonds. They apparently made 150 watches or so. It was also around the same time as Seiko. They just decided not to sell the watches.

    That is to say, the Swiss don’t lack good engineers and scientists. They just lack the executives who are not afraid to make bold moves.

  • Great article, David. Love the story of how this has come to be over so many decades.

    I was expecting better accuracy from the brake system, but I guess that would come at a larger power draw?

    I’m a little surprised by the folks turning their noses at the mechanical + quartz combination: To me, this is as good as modern watchmaking/watch-engineering can get. I’m reminded of the sense of wonder I had when I saw the Breguet exhibit last year in San Francisco, thinking of how he came up with these designs and mechanics – by hand – in what was the dark ages, technology-wise. You might not like the aesthetics, but as far as I’m concerned you have to appreciate the engineering that’s gone into this watch.

    The chronograph’s going on my grail list!

  • Steve Loader

    Brilliant article – great to have all this info in one place at last.

    I recently picked up an Ananta Spring Drive GMT on the Bay, with the intention of selling it on.

    But I must say, the build quality, design, and stunning finishing have blown me away (to give my benchmark, my daily wearer is a Fifty Fathoms).

    This particular watch was deliberately designed to be different (compared to the more conservative Grand Seiko) and it sure works – better than online images can convey. It’s almost as if B&O and Seiko had collaborated on the design!

    I have a small wrist and it’s a big watch, so I may sell it yet, but right now I’m enjoying it too much!

    • Steve Loader

      Oh, forgot to mention, the movement is a dream – beautifully decorated, fascinating sweeping hand, and accurate to around 0.5sec a week (based on tracking against an atomic clock over 4 weeks of daily use).

      …and this is the ‘budget’ 5R66 movement.

  • Mark

    David, Wow, what a great article. Finally, the Spring Drive explained clearly. And please always geek out on the tech specs! I can’t get enough.

  • egznyc

    Amazing stuff, and entertainingly explained. I cannot claim to fully understand the technology (I’m not an engineer – but that’s my own damned fault) but at least I now have a better general understanding of how it all works.

    Thank you for this kind of content.

  • lorneinvan

    My sbga 0011 snowflake was very accurate after initial purchase in April 2016. Recently it has a tendency to run very fast when on days it is worn by me and slowing down when left unworn. I am sending it in for repairs.

  • Jorge Robles

    This article is SUPER!!!! Your research and compilation of this information was by itself a feat and the result is a very well composed and clear explanation of how this technology works. I wish Seiko could license this technology to other watchmakers to see what other companies could do with it, like they did with that TAG-Heuer/Seiko arrangement. I wonder what companies like Omega, Sinn, Tutima and other technical watch companies could do with such a movement!!!! I wish I could have a watch with the design of the Moonwatch model 376.0822 but with this movement, and lots of silicon parts in the gear train and the magic lever. That would be the ULTIMATE watch: Legendary Legibility of the Moonwatch, 24 Hour indicator, Day/Date, Classical case of the Moonwatch line, Magic lever Automatic train with this movement, and being totally antimagnetic!!!! Just dreams of my perfect watch. The nearest to this is the actual Omega, but finding one is getting so difficult….. I wonder if this movement can be obtained from watch suppliers or from Seiko.

  • Ricko Dayat

    Great article, David. really I Love the stor…