# Accuracy of Grand Seiko Spring Drive



## skyWalker

I'm obsessed with the accuracy of mechanical watch. I'm fascinated with how a mechanical watch can attain an accuracy as good as a quartz and how the second hand sweeps continuously and smoothly.

My first Grand Seiko from Japan is a automatic, I'm not at all impressed with it accuracy, it gains more after 9 months although it eventually got regulated to an acceptable range.

I had concluded that spring drive is the way to go.

During my holiday in a small town in Malaysia, I came across a brand new SGBA003, the authorised dealer gave me a very good discount, as good as I get it in Japan, maybe even better. I bought it. It's running slightly more than +1 sec per day. I'm impressed.

.....then few weeks later, in the pre-own market, I came across a full set SBGA111. The deal was too good to walk away. Even though wife is grumbling, I bought it. This watch is even better. It is less than +1 sec per day! I hardly notice any drift !

I think for limited edition watch, Seiko use a better crystal.

Now, I'm the proud owner of 2 Grand Seiko Spring Drive.


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## Watchseeker27

Congrats!! The SBGA111 is a real beauty!


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## whineboy

skyWalker, I agree with you regarding mechanical accuracy. My 1-month old SBGW035 is +6 seconds/day (but it is very consistent).
My $700 Hamilton Jazzmaster is +/- 1 second/day.
The GS is slightly prettier, however.
Maybe my next GS will be an SD. Thanks for tempting me.


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## Molle

The SBGD001 is roughly +5 seconds in a month.

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## Allan_de_dub

I don't even check the accuracy of my Spring Drive anymore haha. My SBGE001 is about 4 seconds fast after I don't even know how many months anymore I reckon it has been more than 4 months. I can only imagine the SBGA103 is the same if not better considering it is guaranteed to be more accurate.

Regarding the mechanical Grand Seikos my old SBGR053 was consistently less than 1 second off a day after I had it regulated so the 9S series of movement can be very accurate.


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## skyWalker

Everything being equal, is it true that some crystals/quartz are better than the others ?

Or the crystal is the constant whereas the rest are the ones affecting the accuracy ?

I thought after all these years, crystal should have insignificant deviations from each other....


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## mpalmer

Spring Drive technology is unique and super geeky cool... Enjoy!


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## dinodays

My understanding is that Seiko "grows" their own crystals. The higher end GS get first dibs on the better quality quartz. It seems that all quartz is not equal. I am simply rehashing what I read elsewhere on understanding spring drives -my appreciation for them has grown. 


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## Allan_de_dub

skyWalker said:


> Everything being equal, is it true that some crystals/quartz are better than the others ?
> 
> Or the crystal is the constant whereas the rest are the ones affecting the accuracy ?
> 
> I thought after all these years, crystal should have insignificant deviations from each other....


On a quartz or Spring Drive the crystal would be the biggest determinant of accuracy. I know some of the limited Grand Seiko Spring Drive models are guaranteed to be more accurate because they have specially selected quartz crystals, not because the going train is made to a higher tolerance.


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## Foxman2k

Allan_de_dub said:


> On a quartz or Spring Drive the crystal would be the biggest determinant of accuracy. I know some of the limited Grand Seiko Spring Drive models are guaranteed to be more accurate because they have specially selected quartz crystals, not because the going train is made to a higher tolerance.


That is supposedly true. My SBGA105 has the "super spring drive". But honestly we are probably taking .1 to .2 seconds every few weeks. Spring drive alone is VERY accurate.


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## Borys Bozzor Pawliw

One thing I have seen is that quartz accuracy really can depend on temperature, both ambient and the influence wrist time has. Related to this, one thing that people don't really mention but when you think about it is very relevant is how some quartz crystals are better isolated from ambient temperature than others. This can depend on the material of the watch, where the quartz oscillator is situated in the movement and what surrounds it. Grand Seiko takes this into account for both its quartz and SD range, hence the exceptional accuracy and stability.


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## eblackmo

Is it weird that I don't care about the accuracy of any of my watches? Unless it is noticeably losing or gaining seconds. It's not something I think about. Is there something wrong with me? Just about everyone else on WUS seems to be obsessed with it.

Also do you guys have timing machines? I have always wondered what methods people use to measure accuracy.


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## skyWalker

I used an old app on my PC to time my watches. Atomtime Pro. It's a freeware.


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## paskinner

These watches are so accurate that it ceases to matter.


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## JK919

Just wish they made the spring drives a bit thinner.


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## appleb

eblackmo said:


> Is it weird that I don't care about the accuracy of any of my watches? Unless it is noticeably losing or gaining seconds. It's not something I think about. Is there something wrong with me? Just about everyone else on WUS seems to be obsessed with it.
> 
> Also do you guys have timing machines? I have always wondered what methods people use to measure accuracy.


Timing machines don't work on Spring Drives since there is no actual beat to measure. I imagine most owners are just eyeballing the differences.


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## Snuggie

Both my SDs are running close to +2s a month! Crazy!


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## BigSeikoFan

My SBGA105 was fast by 3 seconds over eight months! I'm still stunned when I think about that. Talk about luck of the draw...


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## drbojangles

Trust the Japanese to make something that utilises the best of both worlds.


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## Btreichel87

My SBGA099 gains 1 sec every 2-3 weeks. I set all my other automatic watches to it b/c ik the accuracy is so impressive.


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## zuiko

My SBGC013 that has the gold stamp on the rotor was less than 0.5 seconds out after 6 months when I wore it continuously as my only watch. Even 0.5 is overstating it. It is by far my most accurate mechanical SD watch.


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## slipstream

Wow. That's amazing. I've never tested mine. Now it's back from a service I'll have to check. SBDB001


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## paskinner

One other point, these watches do not suffer from the positional variations experienced by purely mechanical designs.


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## Prince Escalus

How does one check the accuracy of a watch, I have a Spring Drive, synced time with an auto about 3 weeks ago now theres about 5 seconds difference between the two 

Im not overly bothered but I am aware because I set them.


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## JK919

Prince Escalus said:


> How does one check the accuracy of a watch, I have a Spring Drive, synced time with an auto about 3 weeks ago now theres about 5 seconds difference between the two
> 
> Im not overly bothered but I am aware because I set them.


The WatchTracker app on the iPhone is pretty good. It has a graph to track changes over time.

I'm kind of curious: what's the worst accuracy you've seen on a spring drive? Seiko is conservative with their ratings so it seems not many come close to the +/- 15 sec per month.


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## whineboy

I have my doubts about the watchtracker app - I check time two ways, with the app, and also against the Time.is clock.
The app gives worse accuracy figures than a daily check against the clock. 
But since these are mechanical watches, what is a second or three a day, after all?


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## RickS72

JK919 said:


> .............. I'm kind of curious: what's the worst accuracy you've seen on a spring drive? Seiko is conservative with their ratings so it seems not many come close to the +/- 15 sec per month.


I own a SBGA011 Snowflake. It gains one second every three days, so, + 10 sec per month. It would be interesting to hear if any SD owners approach the
+ 15 sec/mth.


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## bluedialer

RickS72 said:


> I own a SBGA011 Snowflake. It gains one second every three days, so, + 10 sec per month. It would be interesting to hear if any SD owners approach the
> + 15 sec/mth.


The OP seems to... but I find it hard to believe. He seems thrilled anyway though  I hope he's mistaken, because 1 sec/day is way over than it should be.
Mine has always been about 3 seconds per month. It's on a longer than usual run in my rotation now; on Christmas eve I set it about 1.5sec slow and today it's about 1.8 fast (yes eyeballing ). So +3.3sec in 39 days; 0.085s/day; about 2.55/month

My question is, if timing is pretty much dependent on the crystal, will these watches always run at their current known deviations provided the gears are properly serviced? If you don't like your Jedi lightsaber crystal, can you ask them to replace it at service? Or would they automatically tend to change the crystal during a full service, and those with super awesome crystals might lose theirs? I'm quite happy with mine. But obviously some have it better than others.


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## teb1013

I must get a GS SD. I'm fascinated with it. My SBGV 027 quartz is right on without a second's difference on WatchTracker after a month. Clearly the Spring Drive will never reach that accuracy level, but for an essentially mechanical watch (albeit Quartz regulated) to be as accurate as everyone says is wonderful, my Tudor Black Bay is very good for accuracy but it gains about 3 spd, my newly serviced Rolex Datejust is a little more than that. Also the GS watches are quite unique in beauty. Post pictures please!


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## AKM

RickS72 said:


> I own a SBGA011 Snowflake. It gains one second every three days, so, + 10 sec per month. It would be interesting to hear if any SD owners approach the
> + 15 sec/mth.


My SBGE027 also gains one second every three days and I had it from new. Perhaps it will slow down over time.


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## JK919

My SBGA085 has been trending at +1 sec per month, maybe slightly less.


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## Seagull S6

BigSeikoFan said:


> My SBGA105 was fast by 3 seconds over eight months! I'm still stunned when I think about that. Talk about luck of the draw...


My SBGA105 is pretty darn good too although I don't think it's as good as yours. I think it gained about 1 to 1.5 seconds per month back when I still bothered to measure it.

On a side note, it seems like there are a lot of SBGA105 owners here on WUS. It would be funny if all 500 were owned by us members!


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## Lorneinvan

I have the snowflake Sbg0011 spring drive. It was very accurate when I first purchased in April 2016. Recently it has been running very fast 10 seconds/day on days that it is worn and then slows down when left off my wrist. Has anyone experienced this?


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## djsick

Hi!

My blizzard is 0,25sec/day fast (average of 0,23 over 30days).

There seems to be a group of people who have a deviation of 1sec every 3-4days (like me) and a groupe of people who have a deviation a a few second only a month. Such a difference between Spring Drive watches is peculiar ?

It seems also that SD always "speed up" (not slow down). And for my part, the deviation is very steady it does not matter if I wear it or not.



> I have the snowflake Sbg0011 spring drive. It was very accurate when I first purchased in April 2016. Recently it has been running very fast 10 seconds/day on days that it is worn and then slows down when left off my wrist. Has anyone experienced this?


If you are timing it well, 10sec/day is not normal! I would send it to Seiko Japan If I were you !


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## JK919

Hmm so do spring drives speed up as they age?


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## paskinner

I have had mine about a year, worn about one week a month. Accurate to one second a month, or better. Ten seconds a day is a fault.......assuming it is properly wound.


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## Lorneinvan

I used WatchTracker to time the watch. The consistent pattern has been good accuracy if not worn but once worn it would run very fast. It is self winding. I sent it in to Seiko


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## ciphermonk

Lorneinvan said:


> I used WatchTracker to time the watch. The consistent pattern has been good accuracy if not worn but once worn it would run very fast. It is self winding. I sent it in to Seiko


I've been tracking both my SD watches. The snowflake (SBGA211) is 2.6 seconds fast after 15 days since last sync so about +.17 per day.

The chronograph SBGC225 is running a bit faster at 2.9 seconds fast after 15 days since last sync or about +.19 per day.

So far both are tracking well below the +/-1 guaranteed by Seiko. Pretty impressive for a mechanical movement.

That said, my Solar quartz chronograph is .7 seconds fast after 15 days; so +.05 per day.


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## whineboy

ciphermonk said:


> I've been tracking both my SD watches. The snowflake (SBGA211) is 2.6 seconds fast after 15 days since last sync so about +.17 per day.
> 
> The chronograph SBGC225 is running a bit faster at 2.9 seconds fast after 15 days since last sync or about +.19 per day.
> 
> So far both are tracking well below the +/-1 guaranteed by Seiko. Pretty impressive for a mechanical movement.
> 
> That said, my Solar quartz chronograph is .7 seconds fast after 15 days; so +.05 per day.


I agree, that's impressive accuracy, a brilliant fusion of technologies. Something none of my mechanicals can come close to. But it should be that good, SD watches use a quartz oscillator and microprocessor to regulate the unwinding of the mainspring by electromagnetic braking of the glide wheel, and the associated turning of the hour/minute/second hands. So I wouldn't characterize SD as a pure mechanical movement.

SD compares the quartz oscillator signal to the glide wheel motion and brakes the glide wheel as necessary for accurate timekeeping. In contrast, a mechanical escapement is just 'set and forget', there's no feedback loop as with the SD microprocessor.

Timeless has a nice explanation here: http://www.timelessluxwatches.com/reviews/how-spring-drive-works


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## closeset

SBGA111 has one of the best dials in GS
Congrats!!


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## whineboy

closeset said:


> SBGA111 has one of the best dials in GS
> Congrats!!


Agreed. Though I prefer the symmetry of the Mt. Iwate dials on the high-beat GMTs.

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## biokeys87

I finally downloaded an app earlier this month and my Snowflake is averaging around + 0.1 seconds per day. It can vary, but it hasn't even gained three seconds in just over three weeks. Incredible!

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## Ultrasport

I have a Snowflake that I bought brand new in February from an AD. Frankly, I'm disappointed in that it is running 23-25 seconds per month fast, consistently. The consistently part doesn't surprise me at all because the rate of the Spring Drive should be tied to the frequency of the crystal but the fact that it is SO fast bothers me. I contacted Seiko New Jersey, (the ONLY place that can service them, according to Grand Seiko) and they said to send it in and they'd check it. I'm VERY leery of doing this on a brand new watch. I'm also disappointed that Seiko expects me to pay to ship and insure a brand new watch. I could understand if it was out of warranty or if it didn't turn out to have the "defect" I described but according to an email and a phone call, that's their policy. 

I'd be interested in other's comments. I rotate my watches and keep them is pristine condition. This one is absolutely lik enew with NO marks on it. I REALLY hate to send it to some person in New Jersey and possibly get it back with scratches or obvious evidence of having been worked on. I can see that becoming a never ending battle to get fixed.

Maybe the best thing to do is accept (what I perceive to be) the very poor accuracy of Grand Seiko's flagship watch and chalk it up to a lesson learned.

Comments?

Steve


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## BrianBinFL

Ultrasport said:


> I have a Snowflake that I bought brand new in February from an AD. Frankly, I'm disappointed in that it is running 23-25 seconds per month fast, consistently. The consistently part doesn't surprise me at all because the rate of the Spring Drive should be tied to the frequency of the crystal but the fact that it is SO fast bothers me. I contacted Seiko New Jersey, (the ONLY place that can service them, according to Grand Seiko) and they said to send it in and they'd check it. I'm VERY leery of doing this on a brand new watch. I'm also disappointed that Seiko expects me to pay to ship and insure a brand new watch. I could understand if it was out of warranty or if it didn't turn out to have the "defect" I described but according to an email and a phone call, that's their policy.
> 
> I'd be interested in other's comments. I rotate my watches and keep them is pristine condition. This one is absolutely lik enew with NO marks on it. I REALLY hate to send it to some person in New Jersey and possibly get it back with scratches or obvious evidence of having been worked on. I can see that becoming a never ending battle to get fixed.
> 
> Maybe the best thing to do is accept (what I perceive to be) the very poor accuracy of Grand Seiko's flagship watch and chalk it up to a lesson learned.
> 
> Comments?
> 
> Steve


What time base have you used to determine it is 23-25 seconds per month fast?

Personally I'd rather have a watch be a bit fast than a bit slow because I'd rather be early for things than late (even though we're talking about a quantity of seconds that is shy of even half a minute).


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## Charles Carroll

whineboy said:


> skyWalker, I agree with you regarding mechanical accuracy. My 1-month old SBGW035 is +6 seconds/day (but it is very consistent).
> My $700 Hamilton Jazzmaster is +/- 1 second/day.
> The GS is slightly prettier, however.
> Maybe my next GS will be an SD. Thanks for tempting me.


Whineboy,

I can't resist!

I have owned the Snowflake a month now. When I started the Snowflake I set it 5 secs ahead of the Official NIST U. S. time. When I checked 1 April it was still 5 secs ahead. Exactly 5 secs ahead! I don't expect this to happen next month, but who knows?

Regards,
Charles

Ps. How are you doing with that beautiful Spring Drive Credor?


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## whineboy

Charles Carroll said:


> Whineboy,
> 
> I can't resist!
> 
> I have owned the Snowflake a month now. When I started the Snowflake I set it 5 secs ahead of the Official NIST U. S. time. When I checked 1 April it was still 5 secs ahead. Exactly 5 secs ahead! I don't expect this to happen next month, but who knows?
> 
> Regards,
> Charles
> 
> Ps. How are you doing with that beautiful Spring Drive Credor?


Hello Charles, kind of you to remember me!

Not many of us get perfection in a watch, I'm glad someone who is as thoughtful as you did. Enjoy that terrific Snowflake. Don't forget the WUS motto - "pix or it didn't happen".

The Credor is on the wrist for a few days (I'm looking at the Glashutte Original Senator Panorama Date Moonphase which is very similar in appearance but with the added moonphase complication and blued hands and I want to have the Credor in mind when I compare). It gains a second every 3 days without fail. Since the 7R87A movement is older than the 9R series, I'm satisfied.


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## mleok

Ultrasport said:


> I have a Snowflake that I bought brand new in February from an AD. Frankly, I'm disappointed in that it is running 23-25 seconds per month fast, consistently. The consistently part doesn't surprise me at all because the rate of the Spring Drive should be tied to the frequency of the crystal but the fact that it is SO fast bothers me. I contacted Seiko New Jersey, (the ONLY place that can service them, according to Grand Seiko) and they said to send it in and they'd check it. I'm VERY leery of doing this on a brand new watch. I'm also disappointed that Seiko expects me to pay to ship and insure a brand new watch. I could understand if it was out of warranty or if it didn't turn out to have the "defect" I described but according to an email and a phone call, that's their policy.
> 
> I'd be interested in other's comments. I rotate my watches and keep them is pristine condition. This one is absolutely lik enew with NO marks on it. I REALLY hate to send it to some person in New Jersey and possibly get it back with scratches or obvious evidence of having been worked on. I can see that becoming a never ending battle to get fixed.
> 
> Maybe the best thing to do is accept (what I perceive to be) the very poor accuracy of Grand Seiko's flagship watch and chalk it up to a lesson learned.
> 
> Comments?
> 
> Steve


I would probably leave it as is. While the accuracy is somewhat disappointing, in the grand scheme of things, having to adjust the time once every other month is probably less of a hassle than shipping the watch back when it's in pristine condition and worrying about what cosmetic damage might be inflicted during service.


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## mleok

whineboy said:


> Hello Charles, kind of you to remember me!
> 
> Not many of us get perfection in a watch, I'm glad someone who is as thoughtful as you did. Enjoy that terrific Snowflake. Don't forget the WUS motto - "pix or it didn't happen".
> 
> The Credor is on the wrist for a few days (I'm looking at the Glashutte Original Senator Panorama Date Moonphase which is very similar in appearance but with the added moonphase complication and blued hands and I want to have the Credor in mind when I compare). It gains a second every 3 days without fail. Since the 7R87A movement is older than the 9R series, I'm satisfied.
> 
> View attachment 14034951


The movement of that watch is very pretty. Found a photo on reddit, not sure if it's from you.


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## whineboy

mleok said:


> The movement of that watch is very pretty. Found a photo on reddit, not sure if it's from you.


Agreed, it's really lovely (you can see most of the glide wheel spinning (it's finished with graining) as well as the adjacent wheel rotating). Much more to enjoy than the 9R31.

Not my photo - too good to be mine. I do have a few of the movement here on WUS.


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## Ultrasport

I'm a HAM radio operator as well so I have access to a very accurate time signal from WWV. I've also checked it against my cell phone over a number of days. Both agree it's running 23-25 sec/month fast. I realize it's better than COSC standards but it's disappointing to spend this amount of money on a watch that is SUPPOSED to be accurate to plus/minus 15 seconds a month and have it be so far off. Frankly, based on most of the reports I have seen, I really expected it to be considerably better than 15 per month but even that would have been "acceptable".

Having read a lot about the Spring Drive before buying one, I really thought Grand Seiko was truly trying to compete against companies the likes of Rolex and Omega. I would have expected them to be SURE that every watch performed MUCH better than specification and it if didn't, I would have expected them to at least seem concerned and want the watch back. That's what gets the excellent reputation that I thought they had. I'm very disappointed to say the least.

When I contacted Seiko New Jersey... *the ONLY place in the USA that can service the watch*, it was particularly surprising and disappointing to hear the response that I had to pay for shipping and insurance to repair THEIR mistake. If they had said "We'll reimburse you for the shipping costs once we verify the defect", it would have set better.

I'm sure there are those that would say I am being too picky. I simply feel that the response I received from Seiko USA is unacceptable for a watch of this supposed quality. Having worked in QA for a number of years, I can tell you that most customer's perception of a company's quality is based on how well the company meets or EXCEEDS the customer's EXPECTATIONS. In this case, Seiko has certainly not met my expectations or even its own specification and it will definitely influence my future purchasing decisions.


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## Ultrasport

mleok said:


> I would probably leave it as is. While the accuracy is somewhat disappointing, in the grand scheme of things, having to adjust the time once every other month is probably less of a hassle than shipping the watch back when it's in pristine condition and worrying about what cosmetic damage might be inflicted during service.


I tend to agree with you. Just surprising and disappointing.


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## mleok

whineboy said:


> Agreed, it's really lovely (you can see most of the glide wheel spinning (it's finished with graining) as well as the adjacent wheel rotating). Much more to enjoy than the 9R31.
> 
> Not my photo - too good to be mine. I do have a few of the movement here on WUS.


It definitely looks much more visually interesting to me than the 9R31.

There are a number of nice videos about Grand Seiko by Hodinkee.














And there is this long video which demonstrates the assembly of the Spring Drive movement.


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## BrianBinFL

Ultrasport said:


> I'm a HAM radio operator as well so I have access to a very accurate time signal from WWV.


Hello from a fellow ham. I don't do shortwave so never tuned in WWV.



Ultrasport said:


> I've also checked it against my cell phone over a number of days. Both agree it's running 23-25 sec/month fast.


If your phone is like mine, mine is wrong relative to NIST time by a varying number of seconds at any point in time. I bring up http://time.is on my phone when checking watch sync and the page will also tell you how "off" your phone's time is.

If it really is +23-25 per month (8-10 seconds off spec) and the variance bugs you then by all means submit it for warranty work. I don't wear my Spring Drive every day so I honestly don't know how mine does over a full month.

Unlike the 100% mechanical Grand Seiko watches the Spring Drive watches do not come with an accuracy certificate. I assume that means they have not been tested in the various positions at the various temperatures like the 9R's have. Perhaps they don't test/check them at all and figure the design precludes the necessity of doing so.

I really think that if Grand Seiko wants to play with the big boys they need to complete the separation from Seiko and have their own U.S. service center that offers an experience that is appropriate for this level of timepiece.


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## gychang03

Spring drive is awesome


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## cheznous

gychang03 said:


> Spring drive is awesome


My Snowflake continues to amaze me. In terms of accuracy it appears to be running at less than 1 second per month fast.

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## Takvorian

I own a Snowflake and a SBGA375 and have both tracked with Watchtracker for iOS (great app!) for more than 10 days while wearing them.

Both are 0.2 seconds per day fast. I am very impressed! My Lange 1 is around +3spd.


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## lvt

How dare you question the accuracy of a Spring Drive watch?


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## BrianBinFL

Takvorian said:


> I own a Snowflake and a SBGA375 and have both tracked with Watchtracker for iOS (great app!) for more than 10 days while wearing them.
> 
> Both are 0.2 seconds per day fast. I am very impressed! My Lange 1 is around +3spd.


It seems that almost everyone who has the ability to measure the accuracy precisely reports their spring drive to be right in the vicinity of +0.20 spd. My SBGA375 and SBGA373 are both right around +0.18.

Any time someone reports that their Spring Drive has accuracy significantly less than or greater than that my first suspicion is that their assessment procedure isn't up to par.

Enjoy that smooth sweep.


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## cheznous

BrianBinFL said:


> It seems that almost everyone who has the ability to measure the accuracy precisely reports their spring drive to be right in the vicinity of +0.20 spd. My SBGA375 and SBGA373 are both right around +0.18.
> 
> Any time someone reports that their Spring Drive has accuracy significantly less than or greater than that my first suspicion is that their assessment procedure isn't up to par.
> 
> Enjoy that smooth sweep.


I understand what you are saying but mine appears to be running at 1sec per month worse case, best case 0.5 sec. Interesting to see other comparisons. I use both manual check to Watchville and Time apps and also Toolwatch.

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## BrianBinFL

cheznous said:


> I understand what you are saying but mine appears to be running at 1sec per month worse case, best case 0.5 sec. Interesting to see other comparisons. I use both manual check to Watchville and Time apps and also Toolwatch.


If that's what you're getting then that's fantastic. I'm not familiar enough with those tools to form an opinion about them. My method is rather laborious and inconvenient but it is essentially error proof.

In any event if those tools are telling you it's 1 second a month your watch is going great, so enjoy it.


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## gychang03

Have any of you ever heard of issues with Spring Drive accuracy issues in extreme heat? Quartz accuracy is dependent on temperature and SD is dependent on quartz. anyone have any thoughts?


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## dwalby

No direct experience, but... the spring drive stated accuracy is spec'd for on wrist in temps from 5-35C. If you happen to wear it in temps over 35C, I suspect that will be for relatively short periods of time. The accuracy change of quartz over temp between say 35C and 45C isn't going to be anything significant over a few hours, and after a few hours I suspect you're going to be hot enough to get out of the heat. The spec'd operational temp range of the spring drive is -10 to 60C.


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## GMT-man

gychang03 said:


> Have any of you ever heard of issues with Spring Drive accuracy issues in extreme heat? Quartz accuracy is dependent on temperature and SD is dependent on quartz. anyone have any thoughts?


I do not think the problem would be accuracy, after all why and how one would use a spring drive watch in extreme heat for a long time? Meaning days and days. I have destroyed a first generation beautiful Seiko quartz chronometer (1984) by wearing it to sauna; battery leaked. Idiot me. Spring drive does not have a battery, but mechanical watches get destroyed (not totally killed, but have to be cleaned) by heat because the lubricants get too runny. SD is almost 100% mechanical. SD has capacitors in the regulator, which might leak at high temperatures.


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## Sparrowhawk

GMT-man said:


> I do not think the problem would be accuracy, after all why and how one would use a spring drive watch in extreme heat for a long time? Meaning days and days. I have destroyed a first generation beautiful Seiko quartz chronometer (1984) by wearing it to sauna; battery leaked. Idiot me. Spring drive does not have a battery, but mechanical watches get destroyed (not totally killed, but have to be cleaned) by heat because the lubricants get too runny. SD is almost 100% mechanical. SD has capacitors in the regulator, which might leak at high temperatures.


I thought that SD movements have no capacitors. That all of the electricity is generated in real time, not stored.

I could be incorrect.


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## Sassi

Sparrowhawk said:


> I thought that SD movements have no capacitors. That all of the electricity is generated in real time, not stored.
> 
> I could be incorrect.


You are correct. No battery or capacitor for storing electricity.


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## GMT-man

Sassi said:


> You are correct. No battery or capacitor for storing electricity.


Perfectly true. But I suspect that it is practically impossible to build an electronic speed control system without at least some capacitors in the circuit. Even though tiny.


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## BrianBinFL

GMT-man said:


> Perfectly true. But I suspect that it is practically impossible to build an electronic speed control system without at least some capacitors in the circuit. Even though tiny.


I have read that the Spring Drive contains a very small capacitor (not the battery-like capacitors in kinetic and solar watches) just for power smoothing and to keep the TSR from losing power when the watch is hacked during time setting. If I recall correctly if you keep the crown pulled out for longer than 30 minutes you'll exhaust the capacitor and when you push the crown in the watch will freewheel like it does when you first wind it (when the TSR is not yet powered up).

I have not tested any of the above, just going by what I've read.


----------



## lvt

BrianBinFL said:


> I have read that the Spring Drive contains a very small capacitor (not the battery-like capacitors in kinetic and solar watches) just for power smoothing and to keep the TSR from losing power when the watch is hacked during time setting. If I recall correctly if you keep the crown pulled out for longer than 30 minutes you'll exhaust the capacitor and when you push the crown in the watch will freewheel like it does when you first wind it (when the TSR is not yet powered up).
> 
> I have not tested any of the above, just going by what I've read.


Technically, this does make sense.

I also have a question, does anyone know whether the power reserve indicator on a SD is mechanical (directly geared to mainspring) or electronic (it just reads the voltage from the capacitor or generator)?


----------



## koolpep

lvt said:


> Technically, this does make sense.
> 
> I also have a question, does anyone know whether the power reserve indicator on a SD is mechanical (directly geared to mainspring) or electronic (it just reads the voltage from the capacitor or generator)?


That's mechanical.


----------



## GMT-man

lvt said:


> Technically, this does make sense.
> 
> I also have a question, does anyone know whether the power reserve indicator on a SD is mechanical (directly geared to mainspring) or electronic (it just reads the voltage from the capacitor or generator)?


Voltage is always the same 0.5V and there is no electrical power storage device (battery or power capacitor) in the system, so how could the power reserve gauge be electrical???? All electricity is generated on-the-fly.


----------



## whineboy

koolpep said:


> That's mechanical.


Agreed. In his deconstruction of a Snowflake / 9R65 Spring Drive the Naked Watchmaker shows "The gear train which associates with the power reserve indicator".

https://www.thenakedwatchmaker.com/decon-seiko-snowflake

whineboy

All mechanical, all the time


----------



## lvt

whineboy said:


> Agreed. In his deconstruction of a Snowflake / 9R65 Spring Drive the Naked Watchmaker shows "The gear train which associates with the power reserve indicator".
> 
> https://www.thenakedwatchmaker.com/decon-seiko-snowflake
> 
> whineboy
> 
> All mechanical, all the time


Thanks, good to know.


----------



## gychang03

Does anyone know how many poles the rotor has?


----------



## whineboy

gychang03 said:


> Does anyone know how many poles the rotor has?


All the explanations of Spring Drive I've read refer to one magnet in the glide wheel. So, two poles.

See this one by Joe Kirk, for example: https://deployant.com/ask-deployant-featuring-joe-kirk-on-grand-seiko-spring-drive/

whineboy

All mechanical, all the time


----------



## gychang03

thanks! this is such interesting technology


----------



## BrianBinFL

gychang03 said:


> Does anyone know how many poles the rotor has?


Based upon the scant information available at the moment I agree with Whineboy's answer which is "one". Reading one of the expired Swiss patents that embodiment called for 6 magnets oriented about the spindle, each flipped in polarity relative to its neighbors. Ignoring weight concerns it would seem this would be a very effective arrangement with regard to getting a nice alternating current sine wave (to compare to the reference signal).

Doing the same thing with a single magnet seems like it would be more difficult to set up, not to mention the balance issues that would arise.

Many months ago I sent Joe Kirk a PM here asking this very question and have not received a reply. I suspect he doesn't visit here much anymore.


----------



## whineboy

BrianBinFL said:


> Based upon the scant information available at the moment I agree with Whineboy's answer which is "one". Reading one of the expired Swiss patents that embodiment called for 6 magnets oriented about the spindle, each flipped in polarity relative to its neighbors...


Unless the Swiss patents were Seiko's, you can't infer anything from them regarding how Seiko implemented Spring Drive (my guess is that, being Swiss, they were ETA's, Seiko typically files in Japan first and then extends to the US, Europe, etc.). And even if they were Seiko's, they would at most be evidence of one possible approach, not how the company presently implements the technology in production models.

Being a fan of KISS (keeping it simple, silly), the single-magnet design makes sense to me.


----------



## BrianBinFL

whineboy said:


> Unless the Swiss patents were Seiko's, you can't infer anything from them regarding how Seiko implemented Spring Drive (my guess is that, being Swiss, they were ETA's, Seiko typically files in Japan first and then extends to the US, Europe, etc.). And even if they were Seiko's, they would at most be evidence of one possible approach, not how the company presently implements the technology in production models.
> 
> Being a fan of KISS (keeping it simple, silly), the single-magnet design makes sense to me.


I'm sure however Seiko did it makes more sense than how the Swiss did it since Seiko was able to perfect it into a production article and the Swiss didn't.

I haven't found a Seiko patent that gets into the details of the power generator - only ones that refer to it as though the way it works is assumed.

Here is a picture of the part that Joe Kirk calls the "glide staff". It is the geared spindle that the glide wheel is mounted to, and the gray part is the fixed magnet. (Shown without the glide wheel attached.)









I think part of my confusion (prior to doing a little reading) is I assumed that all ring magnets had their polarity oriented such that, in the position shown above, the top would be one pole (north or south) and the bottom would be the other pole.

If that were the case the lines of flux would look like this (terrible drawing, sorry):









Given the position of the SD wire coils if you spun such a magnet I don't believe any current would be generated.









But I guess I never thought about or realized that a ring magnet doesn't have to be axially magnetized, it can be diametrically magnetized:









Then the lines of flux on our glide staff would look like this:









Given the position of the SD wire coils if you spun such a magnet I believe the desired alternating current would be generated.









Maybe someone will say I have it all backwards, but for now I think I'm good with a single magnet now that I know that ring magnets can be diametrically magnetized.


----------



## Sparrowhawk

That is cool.


----------



## whineboy

BrianBinFL said:


> I'm sure however Seiko did it makes more sense than how the Swiss did it since Seiko was able to perfect it into a production article and the Swiss didn't.
> 
> I haven't found a Seiko patent that gets into the details of the power generator - only ones that refer to it as though the way it works is assumed.


Nice technical analysis, BrianBinFL. It seems well-reasoned to me.

The Wikipedia article on Spring Drive claims there are 230 patents worldwide for SD, citing to a 2012 statement by a Seiko India VP. Not clear to me if that number includes family members in various countries or refers to total families.

This morning I briefly searched for Seiko patents naming Yoshikazu Akahane as an inventor without success. If I find time I'll try a more thorough search.

whineboy

All mechanical, all the time


----------



## BrianBinFL

So I accidentally made an interesting discovery today that seems relevant to this discussion of Spring Drive accuracy.

This will be a long and boring read except for those who enjoy technical minutia.

So I started out with a point of curiosity about how the frequency of a quartz crystal varies with changes in temperature. I assumed that as the temperature rose from room temp the frequency would change in one direction (slower or faster) and as the temperature fell from room temperature the frequency would change in the other direction. That was incorrect.

Apparently the frequency fluctuation relative to temperature is parabolic. The crystal is designed such that at room temperature (assumed to be 25° C) the crystal is at its maximum accuracy (closest to the intended frequency of 32768 Hz in the case of Spring Drive) and as the temperature rises or falls from 25° C the frequency of the crystal slows down by a coefficient as specified for the crystal. The amount it slows down is measured in parts per million (PPM).

The parabola looks like this:









When discussing Spring Drive accuracy the result of around +0.2 SPD (a fifth of a second per day) comes up a lot. The number comes up often enough that I have speculated that GS deliberately calibrates them to run around 0.2 SPD fast. Of course there are also some people who report significantly better accuracy than that, and occasionally worse.

When assessing both of my Spring Drive watches I am comparing to a live-GPS-readout clock that is specified accurate to 100 microseconds, with readout in tenths of a second. I photograph the watch in front of the clock, taking care to observe the watch at the same angle and with the seconds hand in roughly the same position (to minimize parallax), for the starting and ending measurements (with a couple weeks or more elapsed between start and end). Since the seconds sweep is perfectly continuous and never at rest you can get a pretty darn good sync check with a single photograph, no video needed.

Both of my Spring Drives are right in the +0.18 to +0.19 SPD range, with my new SBGA373 coming in at +0.1856 SPD after very careful analysis with the watch staying in the watch box 100% of the time except for winding.

No offense to anybody but to this point I have assumed that whenever I see someone say they are getting accuracy in the 1 second per month range I have assumed that their time reference or methodology was lacking. While that may be the case in some instances, for others it may be a 100% legit observation. Read on.

So once I found out that the temperature/frequency response curve was parabolic (a surprise) then I wondered how much deviation wearing the watch for 9 hours or so would cause. It would be expected to cause some variation because most crystal manufacturers set the "turnover point" (the peak of the parabola) at 25° C and body temperature is about 37° C (12° C warmer). For this analysis I assumed that the crystal would eventually get to full body temperature given direct contact of the watch case with the skin.

The temperature coefficient I see used most often for the type of crystals used in watches is -0.04 ppm/°C². I have no idea if the GS-made crystals have that coefficient or not, but absent better information that's the coefficient I used.

The formula to calculate the PPM is pretty simple:

PPM = -0.04 * (T-T₀)²

So:

PPM = -0.04 * (37-25)²

PPM = -0.04 * (12)²

PPM = -0.04 * 144

PPM = -5.76

So now we know our frequency deviation in parts per million.

Our crystal is supposed to vibrate at 32768 Hz (32,768 vibrations per second). 32,768 Hz is 0.032768 MHz. 0.032768 times -5.76 = -0.18874368. So our error for 9 hours at 37° C is -0.18874368 * 60 * 60 * 9 = -6115.295232 cycles. We need to divide -6115.295232 by 32768 to turn that error back into seconds and we get -0.186624.

Hey, that number looks really familiar. Those of you with really good memories may remember from above that my SBGA373 came in at +0.1856 SPD after very careful analysis. The absolute value of that number is only around a thousandth of a second different than the "9 hours at 37° C" error we just calculated.

Is it possible that GS actually calibrates the Spring Drive so that at room temperature it is just fast enough to offset the loss the watch will experience from a typical day on the wrist? Honestly I wouldn't be surprised if that were the case.

Of course all of this makes a lot of assumptions about the characteristics of GS quartz crystals, and there are probably things that I haven't accounted for, or have perhaps accounted for incorrectly, but I have to say that when I was working out how to do the math and finally calculated my "9 hours" error and saw that number come up, I immediately recognized it and got the biggest grin.

So back to Spring Drive accuracy, given the above it seems completely reasonable that if you wear your Spring Drive for the right number of hours per day, and the rest of the time it is resting at a temperature close to the turnover point in the parabola, you could very well end up getting accuracy of around +1 second in a month.

Anyway, I hope someone gives a darn about all this. I sure had fun working it out.


----------



## Sparrowhawk

That's neat and if true fascinating and elegant.

It would be intetesting to have someone in the know at GS confirm or deny.


----------



## gychang03

BrianBinFL,
This was a great write up. I'm curious to see what temperature the Seiko's crystals are designed for and the assumptions (# hrs daily wear, ambient temp, etc) they utilized in engineering the crystal. With that info, we can modify wearing times in different environments to achieve increased accuracy.. maybe this is going too far. Also, from your other writeup, for sure the magnets are diametrically magnetized.. The weird thing is that it's so far from the coils and magnetic flux falls of a 1/r^2. I would have expected the magnetic poles to be rotating within a series of coils or permanent magnets. This means that those little arms that come off the coils are probably magnetized. Also, for the IC to have a magnetic braking system, it would have to use some type of AC power.. unless of course the windings are actually being used to create two poles in those little arms, one north, one south and the IC pulses the current flowing through the coils, which create the poles used to slow the rotor down. Does anyone know how this thing actually works??!!


----------



## gychang03

BrianBinFL,
This was a great write up. I'm curious to see what temperature the Seiko's crystals are designed for and the assumptions (# hrs daily wear, ambient temp, etc) they utilized in engineering the crystal. With that info, we can modify wearing times in different environments to achieve increased accuracy.. maybe this is going too far. Also, from your other writeup, for sure the magnets are diametrically magnetized.. The weird thing is that it's so far from the coils and magnetic flux falls of a 1/r^2. I would have expected the magnetic poles to be rotating within a series of coils or permanent magnets. This means that those little arms that come off the coils are probably magnetized. Also, for the IC to have a magnetic braking system, it would have to use some type of AC power.. unless of course the windings are actually being used to create two poles in those little arms, one north, one south and the IC pulses the current flowing through the coils, which create the poles used to slow the rotor down. Does anyone know how this thing actually works??!!


----------



## dwalby

That assumes your parabolic curve slope is correct, and there's no temperature compensation being performed inside the SD like they do with the other quartz models, two very big questions.

Do you have any way to temperature control it to something like 37-40C for a couple days so you could get an accurate time drift measurement at that temp?? With your photographic measurement technique it would be best to have a time drift of about 0.5 seconds so its easy to interpolate the seconds hand halfway between two markers. That would take around 38.5 hours at the -5.76PPM offset from the +2.148PPM measured rate @25C. A full second would be even better, no reading uncertainty with that after a little over 3 days.

And even after all that measurement, it doesn't prove anything intentional on the part of GS unless you could find the exact same measurements on dozens of copies of SD watches. But it is interesting nonetheless.


----------



## GMT-man

Interesting. I have two sports watches with thermometers (temperature compensated barometer for air pressure & altitude), and they typically show 32C when worn. I do not believe that a wristwatch would reach body temperature unless it was stuck inside the body somewhere or held in the armpit for long enough.


----------



## Takvorian

@Brian:

A very interesting read and analysis. 

However there is one error here. While it is correct that the body temperature is around 37 degrees Celsius, the outer temperature of the skin is not nearly as warm (just googled). It is usually between 26 and 28 degrees. 

So our watches will never reach 37 degrees with normal wear.


----------



## BrianBinFL

gychang03 said:


> Also, from your other writeup, for sure the magnets are diametrically magnetized.. The weird thing is that it's so far from the coils and magnetic flux falls of a 1/r^2. I would have expected the magnetic poles to be rotating within a series of coils or permanent magnets. This means that those little arms that come off the coils are probably magnetized.


The relationship of the fixed magnet to the coils is an odd one compared to the way electricity is normally generated. I suppose that as the alternating north/south poles of the diametrically magnetized ring pass by each of the "arms" that would cause the magnetization of each arm, with the polarization of that magnetization reversing as the poles pass, North, South, North, South, inducing an alternating current in the coils.



gychang03 said:


> Also, for the IC to have a magnetic braking system, it would have to use some type of AC power.. unless of course the windings are actually being used to create two poles in those little arms, one north, one south and the IC pulses the current flowing through the coils, which create the poles used to slow the rotor down. Does anyone know how this thing actually works??!!


I believe it would be alternating current so that you have a nice sine wave whose frequency you can measure and compare to the reference signal of the quartz crystal. As far as the braking system everything I've read says the TSR "feeds electricity back into the coils" to generate the braking effect. Maybe this is just an artful phrase, but the way I'm familiar with would be to simply place an electrical load, a variable resistor would do fine I think, on the current supply and this will cause a braking effect. If memory serves this is what was described in the Swiss patents, which of course has no bearing one what Seiko did.



dwalby said:


> That assumes your parabolic curve slope is correct, and there's no temperature compensation being performed inside the SD like they do with the other quartz models, two very big questions.


Yes, the coefficient used in the formula will determine the slope of the parabola. The most common coefficient for quartz crystals of the type used in watches is -0.04, but it could just as easily be another value. The guides I read for various temperature compensation strategies (one here) all seemed to use -0.04. Since Grand Seiko makes their own crystals (versus using off-the-shelf components) there is probably no way to know their design spec for this.

Regarding thermo-compensation, GS has specifically stated that Spring Drive does not use thermo-compensation.



dwalby said:


> Do you have any way to temperature control it to something like 37-40C for a couple days so you could get an accurate time drift measurement at that temp?? With your photographic measurement technique it would be best to have a time drift of about 0.5 seconds so its easy to interpolate the seconds hand halfway between two markers. That would take around 38.5 hours at the -5.76PPM offset from the +2.148PPM measured rate @25C. A full second would be even better, no reading uncertainty with that after a little over 3 days.


Last night I was actually pondering how I might hold one of my watches at a stable temperature of 10° above or below 25° C - either one would theoretically produce the same change in rate. The refrigerator is colder than I would want to use. If I had a small unit like you use to chill wine or chocolate in - where the temperature is higher than a refrigerator but still colder than room temperature, that would be good. Somewhere I have an accurate remote thermocouple for measuring the temperature of air conditioning lines. Accurate measurement of the temperature would be important.

While it would be fun I think it's just involved enough that I'd never actually get around to doing it.



dwalby said:


> And even after all that measurement, it doesn't prove anything intentional on the part of GS unless you could find the exact same measurements on dozens of copies of SD watches. But it is interesting nonetheless.


Since my two Spring Drives, both purchased new, have such similar accuracy drift I would suspect they would be representative. Since GS ages their quartz crystals so they can "settle" (frequency wise) I would expect the effect would be similar on any Spring Drive that uses that crystal.



GMT-man said:


> Interesting. I have two sports watches with thermometers (temperature compensated barometer for air pressure & altitude), and they typically show 32C when worn. I do not believe that a wristwatch would reach body temperature unless it was stuck inside the body somewhere or held in the armpit for long enough.


Probably not. That's one of many assumptions on my part that is likely wrong.



Takvorian said:


> However there is one error here. While it is correct that the body temperature is around 37 degrees Celsius, the outer temperature of the skin is not nearly as warm (just googled). It is usually between 26 and 28 degrees.


I'm sure there are lots more than one error in my assumptions.  Regarding the outer temperature of the skin, those numbers are only 1 to 3 degrees warmer than room temperature. I would expect that to be the case for uncovered skin, but I would expect skin that has a mechanical device strapped to it, which prevents it from cooling due to perspiration (in that area), to be somewhat warmer than that. But you're right, I doubt the watch is going to get to 37° C, but GMT-man above reports 32° C. This could be tested pretty easily. I could wear a watch for an hour or so, then take it off and very quickly use a laser thermometer to check the temperature of the caseback. Presumably whatever temperature the caseback gets to the internals will also get to eventually.[/QUOTE]

My entire adventure was based on assumptions and speculation and really is more just food for thought than anything else. I wanted to know how quartz crystals behaved in response to temperature changes and then one thing led to another and eventually I did the math on a naive scenario of room temperature vs body temperature for an arbitrary amount of time. Body temperature is only part of the equation regarding what the temperature of the watch will be. If you are outdoors in the heat or cold, the watch will be receiving a certain heat gain from your skin, and another heat loss or gain from the outside air temperature (which most likely is something other than 25° C).

The fact that the specific number I came up with was so close to the positive SPD variance that so many people report for their Spring Drives is surely coincidence.

That said, now that I know how quartz crystals behave it explains why GS almost certainly sets the SD to run a little fast. Temperature variations would never cause a SD to run faster. Whether the watch is hotter than room temperature or colder than room temperature, both will slow the watch down. So GS probably did a little experimentation to see how much an average day's wear slows the watch down, and then took a guess at what percentage of days the watch would be worn vs not, and biased the watch a little fast to compensate.

This gives rise to all sorts of experiments that could be done to observe the actual behavior of the GS crystals. With enough data points you could confirm or refute that their coefficient is -0.04, and probably make other fun observations as well.

For me it's all about learning things and the big take-away from this for me is that any temperature above or below the turnover point of the crystal will make the crystal run slower. This is not what I had previously assumed and makes a big difference in my understanding of how this all works.


----------



## whineboy

BrianBinFL said:


> .... This will be a long and boring read except for those who enjoy technical minutia.
> 
> Anyway, I hope someone gives a darn about all this. I sure had fun working it out....


Not boring at all to me, BrianBinFL, I do give a darn about this, and tip my hat to your initiative and analysis. Thank you.

I jumped when I saw your conclusions regarding the .2 sec/day daily rate because that is often what I see on my 7R87A handwound Spring Drive - an older movement design that I assumed would not be as accurate as the 9R series. Now, I am not as rigorous as you, I perform a manual timekeeping using the Watch Tracker app, and in the 17 day run below I have an average daily rate of .3 secs.









Thanks also to everyone who expanded upon BrianBinFL's analysis. I learned a lot from all of you.


----------



## whineboy

*()%#$! duplicate post bug :-( .


----------



## dwalby

BrianBinFL said:


> That said, now that I know how quartz crystals behave it explains why GS almost certainly sets the SD to run a little fast. Temperature variations would never cause a SD to run faster. Whether the watch is hotter than room temperature or colder than room temperature, both will slow the watch down. So GS probably did a little experimentation to see how much an average day's wear slows the watch down, and then took a guess at what percentage of days the watch would be worn vs not, and biased the watch a little fast to compensate.


they can probably estimate the watch temp while on the wrist fairly well, but off the wrist there's no standard room temperature, that's going to vary by geography and seasons. You may be storing it at 20C room temp in the winter, 25C room temp in the summer. But if your curve is correct, it would appear that there's really not much deviation in the range of 20-30C, which is where the watch will likely spend the vast majority of its time either on or off of your wrist. In cold climates you'd typically have it under a jacket when outside, so it wouldn't get very cold. In hot climates out in the sun during the day on your bare arm it might get up into the 35-40C range for a few hours, but indoors at a desk its going to be well within that 20-30C range.


----------



## BrianBinFL

I found my bead wire thermocouple and hooked it to the digital thermometer. I put the little stick thermocouple between my wrist and a solid-caseback watch and measured the temperature until it stopped going up. The reading stopped rising at 35.9° C. While this is not the 37° C that I used in my earlier calculations I think it's a lot higher than most here probably expected it would be. Unless you wear your watch loose it makes sense that most of your body heat will be trapped by the watch and therefore be similar to the thermometer in the armpit mentioned previously.

In the beginning the temperature was rising pretty rapidly (as my wrist warmed up the relatively cold watch) but toward the end it was climbing pretty slowly - maybe a tenth of a degree per 30 seconds. I used a watch with a metal case back so that the case back would warm up rapidly as it is a good conductor of heat. Wearing a watch with a glass/sapphire case back would probably affect the heat transmission (since those are insulators) and make the stabilization period longer.

My digital thermometer has two probe inputs so I connected a second thermocouple to the second input and let it measure the ambient air temperature which was 25.1° C. This is pretty darn close to the turnover temperature of 25° C for most quartz crystals used in watches.

Using 35.9° C and 25° C we end up with a PPM of 4.75 (assuming a coefficient of -0.04). This results in a frequency error of 0.155648. With that frequency error it would take around 11.7 hours at 35.9° C to "lose" 0.2 seconds.

Eh, it's all just fun with numbers at this point since we don't know for sure what the thermal coefficient is for the GS crystals. Maybe someday I'll be bored enough to work up a way to keep the watch at a temperature 5° C cooler than turnover for a week and see what it does to the SPD. Somehow I don't see that happening any time soon.


----------



## dwalby

even with a metal case, there's no guarantee that the temp at the crystal inside the case is the same as the case itself. It would probably take a fair amount of time for the internal temp to be stabilized, and since the top of the watch is cooler than the back, the stable internal temp would likely be somewhere between those two temps, not the 35.9C that you measured. And, your comment about transparent backs being much less conductive to heat than a metal back is very true. So I think there's a lot of uncertainty as to the actual internal temp on a SD, even if you know the ambient air temp and your wrist temp.


----------



## BrianBinFL

dwalby said:


> even with a metal case, there's no guarantee that the temp at the crystal inside the case is the same as the case itself. It would probably take a fair amount of time for the internal temp to be stabilized, and since the top of the watch is cooler than the back, the stable internal temp would likely be somewhere between those two temps, not the 35.9C that you measured. And, your comment about transparent backs being much less conductive to heat than a metal back is very true. So I think there's a lot of uncertainty as to the actual internal temp on a SD, even if you know the ambient air temp and your wrist temp.


Agreed. Other than to drill a hole in the case and implant a tiny thermocouple right beside the quartz crystal there is no way to know. And even then it's going to fluctuate based upon what you're wearing, ambient temperature, etc.

Grand Seiko says this about accuracy of the Spring Drive:

Average monthly loss / gain is ±15 seconds when worn on the wrist within a normal temperature range (between 5 ºC and 35 ºC).​
So it would seem they expect you to be in a range of 20º C below turnover point to 10º C above turnover point. Of course they don't plan on you being at those extremes 24 hours a day for the whole month. For the regular quartz watches they say "when worn on the wrist within a normal temperature range (between 5 ºC and 35 ºC) *for approximately 8 hours per day*" so it's probably reasonable to assume that 8 hours of non-room-temperature per day is roughly their expectation for Spring Drive as well.


----------



## gychang03

This was very good insight into how the quartz crystal behaves with temperature fluctuations. and I'm now convinced that GS, and maybe all manufacturers, set their watches fast on purpose. I came across the chart below as I was doing some research.. I believe the crystals used are the xy ones. As in xy cut (tuning fork cut).








Also, this may be going to far but... It seems like the crystals are largely suspended in the air, except for the connection points into the IC. air is a terrible conductor for heat. The air within the watch is both heated from the back and cooled from the top. If the heat from the wrist is going to get conducted, its going to have to move from the caseback, to the case, then towards the middle through where the movement attaches to the case. This is all while competing with the cooler temperature of the watch face and exposed case. It's going to be difficult to determine the actual temperature


----------



## whineboy

gychang03 said:


> Also, this may be going to far but... It seems like the crystals are largely suspended in the air, except for the connection points into the IC. air is a terrible conductor for heat. e


I would expect the crystal oscillator to be held in a vacum-sealed case. Air is awfully variable.

See #7 below (quartz movement, but the same function).










whineboy

All mechanical, all the time


----------



## BrianBinFL

gychang03 said:


> This was very good insight into how the quartz crystal behaves with temperature fluctuations. and I'm now convinced that GS, and maybe all manufacturers, set their watches fast on purpose. I came across the chart below as I was doing some research.. I believe the crystals used are the xy ones. As in xy cut (tuning fork cut).


Available materials suggest that most manufacturers do indeed use XY cut crystals. According to this article Citizen apparently went with AT cut in their 0100 caliber for various reasons. I don't know if the shape of the package is any indicator of what type of crystal lies inside. I looked at a couple examples of XY and AT and it seems like the XY are usually packaged like what I see in the Grand Seiko video (link in next response below).



whineboy said:


> I would expect the crystal oscillator to be held in a vacum-sealed case. Air is awfully variable.


They are definitely in a case - I can't say if they are vacuum sealed, or filled with an inert gas, or something else. Watch this video starting at the 42 second mark to see the quartz crystals being manufactured:


----------



## Watch19

I'm learning so much on this thread. No one I know will care but I find it fascinating.
Thanks guys!


----------



## gychang03

Yeah the quartz crystal is likely sealed up nicely in either a vacuum or some other inert gas.

I'm still struggling with how this rotor generates power.. It seems like the rotor is just too far away from the coils to be effective. Plus the rotor looks like it sits within another metal housing which would further diminish the magnetic field's effect on the coils.








I would expect the design look like this






. which would generate a nice sine wave like this








But from the actual design.. maybe it's more like this







So if this is the case, that takes care of how the ac is generated (still not entirely convinced), but now how does the brakes get applied? still no clue.


----------



## BrianBinFL

gychang03 said:


> I'm still struggling with how this rotor generates power.. It seems like the rotor is just too far away from the coils to be effective. Plus the rotor looks like it sits within another metal housing which would further diminish the magnetic field's effect on the coils.


I agree with you that compared to the usual fixed magnet and coil generators that I am familiar with the generator in the Spring Drive is rather odd. But perhaps not as odd as it seems.

If you've ever taken a fixed magnet and then touched something ferrous to it (like a long bolt) you have experienced that the long bolt is now magnetic and can be used to pick up other ferrous items as though it were the magnet. Then when you separate the bolt from the magnet by enough distance the bolt drops whatever ferrous items are stuck to it.

I believe the generator for the spring drive works in much the same way. The arms with the crescent shaped cutouts that surround the fixed magnet on the glide wheel then pass inside of each of the wound coils of hexagonal shaped wire. We have previously established in this thread that the fixed magnet must be diametrically magnetized so as it spins it imparts "southern" magnetism to one arm and "northern" magnetism to the other arm, then as it makes it to the next half revolution that polarization reverses. I think this would effectively give you two alternating current sources that are 180 degrees out of phase relative to each other (when one is "high" the other is "low"). Either that or the two coils are connected together in series and you have one alternating current supply with one wire coming from one coil and the other wire coming from the other coil.

From the pictures I've looked at it looks like there is only a single pair of contacts so I'm inclined to believe the latter.



gychang03 said:


> So if this is the case, that takes care of how the ac is generated (still not entirely convinced), but now how does the brakes get applied? still no clue.


That depends on how literally you take Seiko's published materials. Seiko says when the TSR needs to apply the brakes it feeds a little bit of the generated electricity back into the coil, causing a magnetic braking effect. I find this notion problematic. There is already a magnetic field being imparted to the metal plate inside the coil which is inducing electrical current in the coil. How can you feed more current back into it than was generated in the first place?

I suspect that perhaps Seiko's answer is a "dumbed down" one and something different is actually happening. Whenever you have a generator that is being spun to produce electricity, if you place an electrical load on the output of that generator it will take more physical work to spin it. Take a car for example. If you are sitting at idle in your car your engine is spinning your alternator to provide the electricity your car needs to operate. If you turn your headlights on you will notice an RPM change in your engine because the additional electrical load on your alternator means now more force is needed to spin it. If the ECU in your car doesn't do something to compensate, the RPM of the engine will drop a little. Chance are the ECU _will_ compensate and the RPMs will quickly return to normal idle (with more force now being applied).

In the case of our Spring Drive the amount of force we can input into the generator is fixed. The mainspring produces what the mainspring produces. Imagine we took the alternating current coming out of the coil and attached a small electrical load to it. This would then cause magnetic resistance to the spinning of the glide wheel and the glide wheel would slow down. When you think about what happens when you attach a load to an electrical supply (electrons move from the negative to the positive) it is _sort of_ feeding electricity back into the coil (in a manner of thinking), legitimizing Seiko's statement on how the braking is done.


----------



## BrianBinFL

Watch19 said:


> I'm learning so much on this thread. No one I know will care but I find it fascinating.
> Thanks guys!


This thread has become the "more than you ever wanted to know about Spring Drive" thread.


----------



## Emceemon

thanks all for the great info

Envoyé de mon iPhone en utilisant Tapatalk


----------



## XOR

To add to your data, have a SBGC203 Spring Drive Chrono. I have worn it every day for a month and taken off at night. It is just under +0.2s/d and is remarkably consistent. I have not taken it off and left it alone to see if it shifts due to temperature cooling off though. I might have to experiment.


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## Sassi

Here is my new SBGA283 after about ten days. Average daily rate is about +0.08 sec/day. :-d


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## BrianBinFL

XOR said:


> To add to your data, have a SBGC203 Spring Drive Chrono. I have worn it every day for a month and taken off at night. It is just under +0.2s/d and is remarkably consistent. I have not taken it off and left it alone to see if it shifts due to temperature cooling off though. I might have to experiment.


That is interesting that yours is +0.2 with _daily_ wear. It would be very interesting to see what it is without daily wear. I would expect it would be a larger variance since daily wear should be slowing it down if our conjecture about the type of crystal is correct.


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## BrianBinFL

Sassi said:


> Here is my new SBGA283 after about ten days. Average daily rate is about +0.08 sec/day. :-d


How many hours a day would you say you wore the watch? This is more like what I'd expect to see from a watch that is worn every day for at least 8 hours.


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## Sassi

BrianBinFL said:


> How many hours a day would you say you wore the watch? This is more like what I'd expect to see from a watch that is worn every day for at least 8 hours.


About 16 hours on average on the wrist and 8 hours in the watch box during night.


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## gychang03

Brian, 
I think you've nailed it. It's got to be "braking" due to loading. I was struggling with the idea of putting more current back into the same system that was generating the power because it doesn't make sense but I think your concept is spot on. That being said, the main spring must be designed to output a relatively constant torque between full and empty and the IC must be designed to be essentially load balanced within that range of torque while it's running. Unless there's some way for them to pull more current, and somehow dissipate it..heating element? Future temperature regulation for the crystal??

let's see if we've got this down..
The main spring is going to be what dictates how fast the rotor with the magnets are going to want to spin while loaded. That in turn dictates the frequency of the current coming in. This frequency eventually evens out but when starting from empty, it must be way high (almost free spinning rotor), and gets loaded by the circuit being energized and slows down. Based on the picture below, I'm thinking that this is what goes through the rectifier and then drives the IC..which I think is likely DC. DC to the crystal and the counter of the crystal. That means the arrow back to the generator is what you've described above.


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## BrianBinFL

gychang03 said:


> DC to the crystal and the counter of the crystal. That means the arrow back to the generator is what you've described above.


I would be interested to know how the frequency comparison is done. A "normal" quartz watch has a divider circuit in it that divides the vibration count by 2 15 times to turn a 32,768 Hz signal into a 1 bps signal (advancing the seconds hand one second per second).

In the Spring Drive the movement isn't so much concerned with how many vibrations equal a second because the seconds hand is moving smoothly and continuously and an "even second" is really no different than any other moment in time (other than perhaps to the observer who notices the alignment of the seconds hand with the mark). In the Spring Drive all the movement cares about is that the frequency of the crystal matches the frequency of the alternating current generated by the glide wheel. If those match then all is well and no adjustments are needed.

Actually I take part of that back. According to Seiko this comparison is done 8 times per second to ensure that no drift has occurred. So in that regard the movement needs to know when 1/8th of a second has passed.

One way to make the comparison 8 times a second would be to constantly divide the vibration count of the crystal by 2 12 times (divide by 2 circuits are simple which is why quartz watches use them). Once the product is "1" then 4096 vibrations have occurred and that's 1/8 of a second. Then compare the count of the crystal to the cycle count of the alternating current signal from the generator, and see if they match.

There are of course other ways that it could be done.

I'd really love to have about an hour or so to discuss all this with a Seiko engineer that knows exactly how all this works. Speculating is fun but knowing would be more fun.


----------



## BrianBinFL

Sassi said:


> About 16 hours on average on the wrist and 8 hours in the watch box during night.


Assuming yours started at about +0.20 and ended up at +0.08, just crunching some rough numbers that seems like a pretty reasonable outcome for wearing it 16 hours a day.


----------



## Sassi

BrianBinFL said:


> Assuming yours started at about +0.20 and ended up at +0.08, just crunching some rough numbers that seems like a pretty reasonable outcome for wearing it 16 hours a day.


Actually that first +0.2 measurement is when I first set the watch to the atomic time. I pushed the button a little too early or set the crown down a bit too early. Usually when monitoring my 100% mechanical watches hitting +/- 0.00 does not really matter at the beginning of accuracy test. Next time I start a new run I will make sure the first reading is set precisely at 0.00. But does the first reading really matter because accuracy is basically calculated from that point onwards, isn't it? :-s:think:


----------



## BrianBinFL

Sassi said:


> Actually that first +0.2 measurement is when I first set the watch to the atomic time. I pushed the button a little too early or set the crown down a bit too early. Usually when monitoring my 100% mechanical watches hitting +/- 0.00 does not really matter at the beginning of accuracy test. Next time I start a new run I will make sure the first reading is set precisely at 0.00. But does the first reading really matter because accuracy is basically calculated from that point onwards, isn't it? :-s:think:


Right. I wasn't referring to your initial sync being +0.2 (in fact I didn't even notice it) I meant that making the assumption that without wearing the watch it would be +0.2 a day as so many other people report.

I'm sure your app compensates for the initial sync error when doing its computations.


----------



## gychang03

BrianBinFL said:


> I'd really love to have about an hour or so to discuss all this with a Seiko engineer that knows exactly how all this works. Speculating is fun but knowing would be more fun.


You and I both. Too bad there isn't one on here to straighten things out.


----------



## dwalby

gychang03 said:


> You and I both. Too bad there isn't one on here to straighten things out.


I suspect even if there were one here, they wouldn't be able to say much at the risk of revealing trade secrets regarding the design.


----------



## BrianBinFL

dwalby said:


> I suspect even if there were one here, they wouldn't be able to say much at the risk of revealing trade secrets regarding the design.


That's the frustrating thing about this. Being that I hold one U.S. patent and have been through the process from start to finish, one thing that I learned is that when drafting a patent in that "[t]he information contained in the disclosure of an application must be sufficient to inform those skilled in the relevant art how to both make and use the claimed invention." That said, "it is not necessary to "enable one of ordinary skill in the art to make and use a perfected, commercially viable embodiment absent a claim limitation to that effect."

There are allegedly a multitude of patents covering the Spring Drive. In theory this means there is a treasure trove of information out there about how the thing works. Finding those patents however is not so easy. Even if we found them all, the amount of detail that is included would depend upon the claims. Since Asulab also patented a concept very similar to Spring Drive, Seiko may have included claims of commercial viability to distinguish their invention. If so their patent(s) might include more detail.

But since Seiko has so many patents it is like looking for the proverbial needle in a haystack. I know others with more skill than I are also looking.

The truth is out there.


----------



## DVR

And here I am, content with enjoying the marvel of spring drive. ;-)


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## BrianBinFL

DVR said:


> And here I am, content with enjoying the marvel of spring drive. ;-)


Nothing wrong with that at all. I don't do well with "black boxes" - I have to understand how they work.


----------



## Watch19

BrianBinFL said:


> Nothing wrong with that at all. I don't do well with "black boxes" - I have to understand how they work.


"Black box" describes the workings of my wife's mind pretty well. Did we all marry the same one?.


----------



## BrianBinFL

Watch19 said:


> "Black box" describes the workings of my wife's mind pretty well. Did we all marry the same one?.


Yes. But I have been married for 32 years now and I think I understand how she works pretty well at this point. My god was it a ton of work. Great investment of effort though.


----------



## dwalby

DVR said:


> And here I am, content with enjoying the marvel of spring drive. ;-)


yeah, these forums throw a whole new light on the old saying "ask him what time it is and he'll tell you how to build a watch".

BrianB, I've been through the patent process a few times myself, and found it to be more of a defensive play than anything else. If you can patent as broad a range of concepts as possible, you can prevent competitors from implementing their own solutions that are similar enough to yours that they infringe on one or more patents. So in my experience the strategy was not to get overly specific on details, and remain as general as possible. probably varies somewhat by field, so YMMV.


----------



## whineboy

dwalby said:


> yeah, these forums throw a whole new light on the old saying "ask him what time it is and he'll tell you how to build a watch".
> 
> BrianB, I've been through the patent process a few times myself, and found it to be more of a defensive play than anything else. If you can patent as broad a range of concepts as possible, you can prevent competitors from implementing their own solutions that are similar enough to yours that they infringe on one or more patents. So in my experience the strategy was not to get overly specific on details, and remain as general as possible. probably varies somewhat by field, so YMMV.


dwalby - as a US patent lawyer with 30+ years of experience and 100's of patents granted for my clients, I find your comments very interesting. Do you know what the 'best mode' requirement means?

Edit: yah, I bit down hard on this. I react when people with a patent or three speak as if they know everything about the surprisingly complicated world of patent law.


----------



## Sparrowhawk

Cool, we now know what whineboy does professionally.

I have thought several times that it would be nice to have frequent posters present a quick bio, kind of a who are you in a nutshell, without giving away much PII.


Nice that we have some varied and very smart people on the forum.


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## BrianBinFL

whineboy said:


> Edit: yah, I bit down hard on this. I react when people with a patent or three speak as if they know everything about the surprisingly complicated world of patent law.


As a layperson I know just enough to be dangerous. My patent attorney did compliment me on my level of knowledge but perhaps he was just being kind. I did read a few books (yeah, real paper books) on the patent process and even dug into the Manual of Patent Examining Procedure here and there when a book couldn't give me the answer I needed.


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## BrianBinFL

Well I finally found a Seiko Epson patent for Spring Drive. It is certainly not the _only_ patent, and this one seems to focus heavily on the different arrangements that are possible with the coils, and what changes for each arrangement. But there are still goodies in there. I'll post the patent number after I've had a chance to fully digest it so I'll be in a position to have intelligent discussion about it (which I'm not at the moment).

Here's a teaser:

FIG. 29 shows a generator 200 of a twelfth embodiment of the present invention. The generator 200 of this embodiment is used as a generator of an electronic-controlled mechanical timepiece in the same way as the above-mentioned embodiments, and uses a multipolar magnet 201 as its rotor magnet. This embodiment uses a 14-pole multipolar magnet 201, but may use a multipolar magnet 201 having 10 poles, 18 poles or the like, and a multipolar magnet 201 having at least 4 or more poles will do. In this case, a multipolar magnet 201 having 10, 14 or 18 poles is practical in case that it is assembled into a stator 170 comprising core stators 172 and 173 symmetrical to each other.​








This is much closer to what the Swiss did with their rotor and not at all what we had guessed earlier in this thread. Now that doesn't mean that this is how the current production watches are built - this is just one embodiment in one patent, but after pondering it a bit it seems highly unlikely that we're dealing with a single north/south magnet unless they are downsampling the crystal.

Here is a copy/paste of what I sent whineboy on the topic:

The rotor shown in the patent has 14 oppositely polarized N/S regions on it and the patents suggests you need at least 4 and possibly [up to] 18 [...].

After seeing the 14 that made a lot of sense. If it was a single diametrically polarized magnet it would have to be spinning at 32,768 revolutions per second (RPS) in order to produce a waveform that matches the pulse rate of the quartz oscillator. That's awfully fast. Like Dremel tool on full speed fast. Lots of wear and tear and heat there. Change that to 4 regions of alternating polarity and now you need 16,384 RPS (2 norths and 2 souths = 2 cycles per rotation). Change that to 16 regions (8 norths and 8 souths = 8 cycles per revoltion) and you only need 4,096 RPS.

The more magnets you add the less speed the glide wheel needs to match the 32,768. Now that I think about it if we knew the number of teeth and diameter of every wheel between the mainspring and the glide wheel, it would be possible to calculate what speed the glide wheel must spin to keep proper time. Then you would know how many regions of alternating polarity you would need in order to make that happen. That is unless they are using a divider circuit on the quartz output to bring it down to the glide wheel, but that would seem to sacrifice accuracy and waste electricity doing that math.​


----------



## BrianBinFL

If this Grand Seiko Spring Drive page is telling the truth then the glide wheel "makes *eight* full revolutions every second, generating a slight electric current".

If the glide wheel is only spinning at 8 RPS it would seem the more regions of alternating polarity the better. However, the more regions you have the smaller they are and the weaker their magnetic field, so you have diminishing returns on the current produced.

This would suggest that Seiko is indeed using a divider circuit on the 32,768 Hz coming out of the quartz crystal. What that divider is depends on how many alternating north/south regions on the glide wheel.


----------



## dwalby

whineboy said:


> dwalby - as a US patent lawyer with 30+ years of experience and 100's of patents granted for my clients, I find your comments very interesting. Do you know what the 'best mode' requirement means?
> 
> Edit: yah, I bit down hard on this. I react when people with a patent or three speak as if they know everything about the surprisingly complicated world of patent law.


whineboy, I don't think I wrote anything that suggested I considered myself an expert on anything, and that certainly wasn't my intention with the post. I only briefly stated what I recall from my own experiences on the process, in a sentence or two. Its been close to 20 years since my last patent was granted, so my memory may be a bit off on the details as well. I also found that with high-tech patents, the patent lawyer's understanding of the minor technical details wasn't at the same level as the inventor, so how that information was disclosed was variable. With over 10M patents granted, I'm going to assume that there's quite a bit of variation from one to another as to the strategy deployed in the disclosure process, even though there are standard rules and procedures that should be followed. I seem to recall management getting involved in the process to make the patent coverage as wide as possible, rather than as narrow as possible.


----------



## whineboy

Sparrowhawk said:


> Cool, we now know what whineboy does professionally.
> 
> I have thought several times that it would be nice to have frequent posters present a quick bio, kind of a who are you in a nutshell, without giving away much PII.
> 
> Nice that we have some varied and very smart people on the forum.


:-!

I've mentioned being a patent lawyer from time to time, no secrets there. What's really interesting is that I represented Seiko and Seiko Epson from 2000-2009 (early on I handled a few watch cases, but virtually all my work involved ink jet recording). On my first trip to Suwa we were treated to a presentation by one of Seiko's engineers, who proudly recounted the development of the "3-day watch" that could make it through the weekend without stopping. Now I realize it was probably due to a Spron mainspring.

At that time I did not have the watch bug, so I missed an amazing opportunity to buy a Grand Seiko at the manufacture. Or a tour. Yes, I'm a dunce.

I found Seiko to be a great company, I met some of the kindest and most generous people there. Once, when I was in Suwa over the weekend, the gentlemen whom I worked for most spent a Saturday showing me all sorts of things in the area, including a detailed walkthrough of a Shinto shrine, a tour of a wasabi farm (it was a work of art, as are most things in Japan, the gravel fields where wasabi roots are grown were patterned in chevrons and spirals), and a meal of local delicacies I'll never forget - horsemeat sashimi, yes, fried fish skeleton, no.


----------



## whineboy

dwalby said:


> whineboy, I don't think I wrote anything that suggested I considered myself an expert on anything, and that certainly wasn't my intention with the post. I only briefly stated what I recall from my own experiences on the process, in a sentence or two. Its been close to 20 years since my last patent was granted, so my memory may be a bit off on the details as well. I also found that with high-tech patents, the patent lawyer's understanding of the minor technical details wasn't at the same level as the inventor, so how that information was disclosed was variable. With over 10M patents granted, I'm going to assume that there's quite a bit of variation from one to another as to the strategy deployed in the disclosure process, even though there are standard rules and procedures that should be followed. I seem to recall management getting involved in the process to make the patent coverage as wide as possible, rather than as narrow as possible.


No problem, dwalby, as I said, patents are a big button issue with me. To avoid boring everyone and hijacking this thread I'll PM you with my thoughts.

Sorry if I came across harshly. One of my many shortcomings.


----------



## Sparrowhawk

whineboy said:


> :-!
> 
> I've mentioned being a patent lawyer from time to time, no secrets there. What's really interesting is that I represented Seiko and Seiko Epson from 2000-2009 (early on I handled a few watch cases, but virtually all my work involved ink jet recording). On my first trip to Suwa we were treated to a presentation by one of Seiko's engineers, who proudly recounted the development of the "3-day watch" that could make it through the weekend without stopping. Now I realize it was probably due to a Spron mainspring.
> 
> At that time I did not have the watch bug, so I missed an amazing opportunity to buy a Grand Seiko at the manufacture. Or a tour. Yes, I'm a dunce.
> 
> I found Seiko to be a great company, I met some of the kindest and most generous people there. Once, when I was in Suwa over the weekend, the gentlemen whom I worked for most spent a Saturday showing me all sorts of things in the area, including a detailed walkthrough of a Shinto shrine, a tour of a wasabi farm (it was a work of art, as are most things in Japan, the gravel fields where wasabi roots are grown were patterned in chevrons and spirals), and a meal of local delicacies I'll never forget - horsemeat sashimi, yes, fried fish skeleton, no.


Very cool!

I had seen you are an attorney, just must have missed the patent specialty.

Sounds like an excellent trip to Japan with lasting memories.


----------



## DVR

Whineboy, no need to go pm, I am sure many of us do not understand or want to understand the minute details of SD. But your patent memories re Seiko etc are intriguing. 
I made my money in 'sales' , I started 3 company's from scratch, sold 2 and have loved watches since I was in my twenties.

Tell me though, why no love for SD?? It's the closest anyone will ever get to nature and our own body. 
That's what got to me big time. A SD caliber is mimicking nature and our own body. Everything exists because of electricity combined with 'mechanics'.


----------



## BrianBinFL

DVR said:


> Tell me though, why no love for SD?? It's the closest anyone will ever get to nature and our own body.
> That's what got to me big time. A SD caliber is mimicking nature and our own body. Everything exists because of electricity combined with 'mechanics'.


Whineboy is an SD convert. I think he struggled with it for a bit at the outset due to his "all mechanical, all the time" philosophy, but he eventually decided that in a way of looking at it SD is all mechanical - from the mainspring to the escapement the only things that actually touch the geartrain from start to finish are mechanical. The escapement is electronic but it is a contact-free escapement, allowing perhaps a little philosophical wiggle room.

Whineboy, if I have mischaracterized your early musings on the topic please set me straight.


----------



## whineboy

BrianBinFL said:


> Whineboy is an SD convert. I think he struggled with it for a bit at the outset due to his "all mechanical, all the time" philosophy, but he eventually decided that in a way of looking at it SD is all mechanical - from the mainspring to the escapement the only things that actually touch the geartrain from start to finish are mechanical. The escapement is electronic but it is a contact-free escapement, allowing perhaps a little philosophical wiggle room.
> 
> Whineboy, if I have mischaracterized your early musings on the topic please set me straight.


Perfectly characterized, BrianBinFL. Originally I viewed Spring Drive as a trick quartz movement, but after reading many people's comments here on WUS I did a lot of reading and thinking about what the technology does. Now, I'm a convert (though I only have one SD for now). Probably the biggest factor in my journey was Timeless Luxury Watches' terrific explanation of Spring Drive, which points out SD is 95% the same as a pure automatic movement, and that SD embodies the best of both mechanical (reliable, romantic) and quartz (accurate, durable). Here's the link:

https://timelessluxwatches.com/reviews/spring-drive-works/


----------



## gychang03

It's a great combination of the two technologies. I think that it even goes beyond the two technologies since it actually generates it's own electricity from locomotion. That's something the others don't typically have


----------



## Sassi

Here is an update after two weeks of owning my SBGA283. This week I slept three nights wearing the watch. The overal accuracy is now +0.05 sec/day. I will report again after a full month.


----------



## BrianBinFL

Sassi said:


> Here is an update after two weeks of owning my SBGA283. This week I slept three nights wearing the watch. The overal accuracy is now +0.05 sec/day. I will report again after a full month.


That's fantastic performance Sassi. The more we learn about the movement the more I think Spring Drives are simply built to be worn. I think the more you wear it the closer to +0 over a month you'll get. I think you know you wore it "too much" when you finally end up "losing" time (i.e. you end up with a time that is actually behind instead of ahead).


----------



## BrianBinFL

So I have finished going through the hits from the search technique I came up with to find Seiko Epson U.S. patents related to Spring Drive without having to wade through tens of thousands of them. I was able to find 17 relevant patents out of the preliminary hit pool of 598. Even that was many hours of work. There are supposedly hundreds of patents for Spring Drive, but I was only searching for U.S. patents and I know they have tons of Japanese patents and other foreign patents.

The level of detail in the patents is fantastic for answering a lot of the questions we've been pondering in this thread, and elsewhere. For example the method used to compare the rotational signal to the oscillator signal (which we pondered back here) is explained in excruciating detail in several of the patents.

I have only scratched the surface of actually trying to digest what's in these patents. It would probably take me a year (or several?) to consume all of these patents to full comprehension and I doubt I will ever undertake to actually do that. Instead I will mine them for answers to questions as they arise. I will say that as I have been reading them there have been many occasions for me to grin and say "that's what I thought!". 

Of course these are patents. They describe ways to do things. In some cases they offer many different ways to do the same things. In some cases knowing which embodiments Seiko chose for the production units may not be able to be known with certainty, but the range of choices will still illuminate as to the broad brush technique.

My head is actually swimming right now with all of the material I have digested so far today. So much good stuff. We'll probably want to spin off a "Spring Drive Patent Q&A" topic if we really want to discuss questions you all have and what my answer would be based on the patent documents. For now it's bed time and I'll just leave you all with the list of patents for those of you who, like me, love to read this stuff.

6041021 - Electronically Controlled Mechanical Timepiece and Control Method Therefor
6097675 - Electronically Controlled Mechanical Timepiece
6252828 - Electronically Controlled Mechanical Timepiece and Control Method Therefor
6314059 - Electronically Controlled Mechanical Timepiece and Control Method for the Same
6373788 - Electronically Controlled Mechanical Timepiece
6373789 - Electronically Controlled Mechanical Timepiece and Method Controlling the Same
6373790 - Overcharge Prevention Method, Changing Circuit, Electronic Device and Timepiece
6414909 - Electronically Controlled Mechanical Timepiece and Control Method Therefor
6466519 - Electronic Device, Electronic Timepiece and Power Control Method
6584043 - Electronically Controlled Mechanical Watch and Method of Preventing Overcharge
6633511 - Electronic Controlling Type Mechanical Timepiece
6693852 - Electronic Device, Electronically-Controlled Mechanical Timepiece, and Electronic Device Controlling Method
6795378 - Electronic Device, Electronically Controlled Mechanical timepiece, and Control Method Therefor
6819633 - Braking Without Stopping Generator for Timepiece and Other Electronic Units
6829199 - Electronic Apparatus, Electronically Controlled Mechanical Timepiece, Methods of Controlling Them, Program for Controlling Electronic Apparatus, and Storage Medium
6973010 - Timepiece device
RE38110 - Electronically Controlled Mechanical Timepiece and Control Method Therefor


----------



## gychang03

omg! jackpot...

The electric energy supplied by the generator energizes a slaving circuit that includes a transistor which short-circuits the coil of the generator and thus brakes the rotor down to a speed less than the desired speed Vc when a comparator indicates that this rotor is ahead with respect to its theoretical angular position.

sooooo much good info


----------



## gychang03

omg! jackpot...

The electric energy supplied by the generator energizes a slaving circuit that includes a transistor which short-circuits the coil of the generator and thus brakes the rotor down to a speed less than the desired speed Vc when a comparator indicates that this rotor is ahead with respect to its theoretical angular position.

sooooo much good info


----------



## BrianBinFL

gychang03 said:


> omg! jackpot...
> 
> The electric energy supplied by the generator energizes a slaving circuit that includes a transistor which short-circuits the coil of the generator and thus brakes the rotor down to a speed less than the desired speed Vc when a comparator indicates that this rotor is ahead with respect to its theoretical angular position.
> 
> sooooo much good info


Yes, that was one of my favorite finds so far. As I mentioned previously the explanation floating around that "to effect braking the TSR feeds some current back into the coil" is absurd. Putting a resistive load on the output of the coil (another embodiment in another of the patents shows a resistor) or simply short circuiting the output of the coil, will quite effectively cause an electromagnetic braking effect. No need to make it sound any more complex than that.

I really want to put some time into digesting the strategy they are using for counting the oscillator cycles versus the rotation cycles. Most of the patents show the frequency divider (which affirms my prior speculation that they are dividing the oscillator for their speed comparison) and there was even one that gave a Hz rate for the output of the divided oscillator signal that they then compare to the rotor (glide wheel) speed. They divulge the complete strategy many times across many of the patents.


----------



## Sassi

Here is the accuracy of my SBGA283 after three weeks. This week I ended up losing a little time compared to last week. I wore the watch 5 nights while sleeping and also took it to shower two times. The average rate is now +0.02 sec/day.


----------



## cheznous

Sassi said:


> Here is the accuracy of my SBGA283 after three weeks. This week I ended up losing a little time compared to last week. I wore the watch 5 nights while sleeping and also took it to shower two times. The average rate is now +0.02 sec/day.
> 
> View attachment 14679803


Mine runs around the same. I do not wear it at night though. I thought Spring drive runs the same speed worn or not? Mine was just under 1 sec fast so amended it today. Last adjustment was when the clocks changed on Oct 26th.

Sent from my iPhone using Tapatalk


----------



## Sassi

cheznous said:


> Mine runs around the same. I do not wear it at night though. I thought Spring drive runs the same speed worn or not? Mine was just under 1 sec fast so amended it today. Last adjustment was when the clocks changed on Oct 26th.
> 
> Sent from my iPhone using Tapatalk


Position wise it does not matter but when you are wearing the watch the temperature of the quartz crystal is higher. This affects the accuracy as I have understood it. My own experiences show this in practice.

It seems my watch runs slower if worn and the temperature of the quartz crystal is higher and vice versa.


----------



## ztinier

My 2016 Seiko Grand Seiko is 0.16 seconds fast per day sitting in the watch box.
This was taken over a period of 1 month.


----------



## ztinier

.


----------



## BrianBinFL

ztinier said:


> My 2016 Seiko Grand Seiko is 0.16 seconds fast per day sitting in the watch box.
> This was taken over a period of 1 month.


That's pretty much right in the zone for resting in the box. Out of curiosity approximately what is the average temperature in the room where the watch "lives" while it's in the box?


----------



## BrianBinFL

Just a random piece of information to throw out for those that are diving into the low level of the movement, on this page it says:

_The speed of the seconds hand is regulated by a magnetic brake that is applied 256 times per second._​
I haven't had a chance to delve into the patents again for bit but this seemed like a good number to have handy for any analysis.


----------



## gychang03

to add some info here. I've been wearing my spring drive about 9 hours a day for the last two weeks. Temperatures at the office is 70 F and Average air temp when I take it off is about 80 F. its about two seconds fast over the past two weeks.


----------



## gychang03

how are you guys measuring accuracy to such a high level of degree? Is there some kind of app that you're all using? I'm just eyeballing it


----------



## BrianBinFL

gychang03 said:


> how are you guys measuring accuracy to such a high level of degree? Is there some kind of app that you're all using? I'm just eyeballing it


Most of the guys here are using an app (various ones) that will let you hit a button in the app and the app knows what time it was from an NTP server (never trust your phone's clock, they are terribly inaccurate) and the app asks you what time your phone said when you hit the button and it records the difference. The app will track that for you over time.

As convenient as that is, and as nice as the trend reports it can provide are, I'm waaaaaaaaaaaaaaaaaaaay too anal for that to be accurate enough as your reflexes are a factor in the accuracy of the measurement. Assuming your reflexes are reasonably consistent then this doesn't introduce too much error. If the idea is that you try to hit the button just as your seconds hand marks the top of the minute, how close were your reflexes to hitting the button at the moment your watch actually hit the top of the minute? You have no real way to know.

The way I do mine is COMPLETELY impractical, but satisfies my need to be as close to a perfect analysis as possible. If you are bored and want to read about it you can do so here.


----------



## gangrel

For the far more stringent accuracy to be considered high accuracy quartz...COSC spec is 2 seconds a MONTH, not a day, and we prefer to say 10 seconds per year in f9...there've been various methods. I think mutli-exposure photos would probably be necessary...but with the sweep seconds, you're always gonna have somewhat larger uncertainty.

Me, I never bothered. I eyeball, using a digital time source like time.gov. I'm not bothering trying to project over a short period...if it's 8-10 seconds off after 10 days, it's about a second a day.


----------



## gangrel

For the far more stringent accuracy to be considered high accuracy quartz...COSC spec is 2 seconds a MONTH, not a day, and we prefer to say 10 seconds per year in f9...there've been various methods. I think mutli-exposure photos would probably be necessary...but with the sweep seconds, you're always gonna have somewhat larger uncertainty.

Me, I never bothered. I eyeball, using a digital time source like time.gov. I'm not bothering trying to project over a short period...if it's 8-10 seconds off after 10 days, it's about a second a day.


----------



## gychang03

BrianBinFL said:


> The way I do mine is COMPLETELY impractical, but satisfies my need to be as close to a perfect analysis as possible. If you are bored and want to read about it you can do so here.


Great post! I just checked time.is and they haven't updated it to the tenths of a second yet. hopefully they will soon...for now maybe slo-mo on my phone will work. About stopping and starting within a fraction of a second, are you concerned about inducing some wear on the gears? btw, I recently read a book called "The Order of Time" by Carolo Rovelli. I think you may like it.


----------



## BrianBinFL

gychang03 said:


> Great post! I just checked time.is and they haven't updated it to the tenths of a second yet.


I've checked back with Even Scharning (author of time.is) every now and again to remind him that I'll beta test the tenths feature when he's ready. I don't think it's high on his priority list. If it does ever happen it will not be on by default - it will be an optional setting that can be turned on under "Customize".



gychang03 said:


> About stopping and starting within a fraction of a second, are you concerned about inducing some wear on the gears?


I don't set my Spring Drive hyper-precisely every time I bring the watch into rotation. Because my sync checking method is so cumbersome I generally do it once when the watch is new to confirm the watch is in spec and find out what the starting accuracy is. I might then do it again after a year or so, or if anything were to arise that gave me cause to verify nothing has changed. As long as you're not putting a lot of force on the crown when you pull-push in rapid succession I don't think you're going to hurt anything any more than normal hacking.



gychang03 said:


> btw, I recently read a book called "The Order of Time" by Carolo Rovelli. I think you may like it.


I saw your post while lying in bed last night and ordered the Kindle version of The Order of Time. I read the first little bit where the author outlines what the book is going to cover and how he's going to cover it and I think it will be a fun read.

He started out mentioning the principle that the closer you are to a large mass/gravitational body the slower time passes, and vice versa. I had read an article on that very topic within the past couple months, where they explained the special clocks they had to build, that had a higher resolution than even an atomic clock, in order to be able to prove that time moves more slowly at sea level than it does at any elevation above sea level. That even 6 feet of elevation produces a measurable difference in how fast time passes. In the book the author mentions this as well noting that your head is older than your feet as a result.

There is a lot of fascinating material surrounding the concept of time and it sounds like he's going to pack a bunch of that information in one book. Thanks for recommending it. You are right, it is definitely something I'd like.


----------



## dwalby

BrianBinFL said:


> He started out mentioning the principle that the closer you are to a large mass/gravitational body the slower time passes, and vice versa. I had read an article on that very topic within the past couple months, where they explained the special clocks they had to build, that had a higher resolution than even an atomic clock, in order to be able to prove that time moves more slowly at sea level than it does at any elevation above sea level. That even 6 feet of elevation produces a measurable difference in how fast time passes.


while I've heard these various theories before, I have a hard time wrapping my head around the practical side of it.

For example, if we define one year as the time it takes for the Earth to orbit the Sun, then it makes no sense to me that higher elevations of the Earth would complete that orbit any faster/slower than any other elevation on Earth.

Similarly, if I build an electronic timer with an incredibly stable oscillator, and the timer has something like ns or ps accuracy, what would cause it to run at different speeds as a function of elevation (assume the oscillator doesn't vary as a function of gravity, which I know does change slightly as a function of elevation).

If these questions are addressed in the book, let me know what the author says about it when you get to that part of the book.


----------



## BrianBinFL

dwalby said:


> while I've heard these various theories before, I have a hard time wrapping my head around the practical side of it.


You and me both.



dwalby said:


> For example, if we define one year as the time it takes for the Earth to orbit the Sun, then it makes no sense to me that higher elevations of the Earth would complete that orbit any faster/slower than any other elevation on Earth.


Well, although the whole Earth finishes one trip around the sun at the same point in time, different elevations on Earth will experience a longer passage of time throughout the journey. The so called "time dilation effect". So I live in Florida near sea level. And a friend lives at 1000 feet above mean sea level. He will experience more passage of time during the 1 year trip around the sun than I do. At the end of that trip around the sun he has aged more than I have.

But this effect is VERY small. The folks at NIST that built the aluminum ion clock have measured that a 1 foot increase in elevation will translate to aging an additional 90 billionths of a second over a 79 year lifespan. But I guess that's really the wrong way to look at it. The physics is that the closer you are to an object of massive mass (with comparatively large gravitational pull) the slower time passes for you. So the baseline would be what the passage of time is if you're completely out of any gravitational field of any massive body, and then the closer you get to one the more time slows down for you.

This plays out to the absurd when you think about things like black holes which have an almost incomprehensibly strong gravitational field. If you approached the event horizon of a black hole, the passage of time for you would slow down infinitely such that from your perspective you would never actually enter the black hole. To observers outside the effect of the black hole's gravity you would pass the event horizon and disappear, because time is moving at a different speed for us, but for those actually approaching the event horizon they'd never actually cross it (by their perception).

Bends the mind.



dwalby said:


> Similarly, if I build an electronic timer with an incredibly stable oscillator, and the timer has something like ns or ps accuracy, what would cause it to run at different speeds as a function of elevation (assume the oscillator doesn't vary as a function of gravity, which I know does change slightly as a function of elevation).


That's the crazy thing. If you have an accurate enough clock, like the one NIST built, you find that a clock on the floor will accumulate oscillations slower than the clock that is raised one foot. It wouldn't be right to say "more oscillations in a second" because the concept of what a second is becomes fluid here.



dwalby said:


> If these questions are addressed in the book, let me know what the author says about it when you get to that part of the book.


I will be very interested to see how deeply he goes into any of these various topics that I have read about elsewhere. If gychang03 has already read the whole book perhaps he can comment.


----------



## dwalby

It appears that both gravitational force and velocity affect the rate at which atoms oscillate, since the optical clocks that make these precise "time" measurements are based on atomic oscillations. I can accept that to be a fact. And your comment about "the concept of what a second is becomes fluid" is the crux of the problem of whether there is any merit to that fact. I disagree with your other comment that someone at altitude will "experience more passage of time" during a solar orbit than you will at sea level, they will have simply experienced slightly more atomic oscillations than you did during that same interval. Roughly similar to the concept of your watch being a second per year slower than the other person's watch, all that was different was the perception of time measurement based on an arbitrary reference standard.

Within our limits of technology we'll probably never travel fast enough for those atomic oscillations to change by any appreciable amount, but let's just assume for a moment that we could. That brings up two interesting questions:

1. As things start oscillating significantly more slowly, does the human body age any differently as a result? And if it changes, would we age faster, or slower?? To me that's the only practical application of time dilation taken to the extreme.

2. As things start to oscillate too slowly, does the integrity of all matter start to change?? Would the atoms/molecules that made up the spaceship traveling at that extreme speed (and our bodies) begin to disintegrate?? 

Well, now we've gone and hijacked the thread into oblivion, but it was an interesting thought process.


----------



## Jostack

dwalby said:


> It appears that both gravitational force and velocity affect the rate at which atoms oscillate, since the optical clocks that make these precise "time" measurements are based on atomic oscillations. I can accept that to be a fact. And your comment about "the concept of what a second is becomes fluid" is the crux of the problem of whether there is any merit to that fact. I disagree with your other comment that someone at altitude will "experience more passage of time" during a solar orbit than you will at sea level, they will have simply experienced slightly more atomic oscillations than you did during that same interval. Roughly similar to the concept of your watch being a second per year slower than the other person's watch, all that was different was the perception of time measurement based on an arbitrary reference standard.
> 
> Within our limits of technology we'll probably never travel fast enough for those atomic oscillations to change by any appreciable amount, but let's just assume for a moment that we could. That brings up two interesting questions:
> 
> 1. As things start oscillating significantly more slowly, does the human body age any differently as a result? And if it changes, would we age faster, or slower?? To me that's the only practical application of time dilation taken to the extreme.
> 
> 2. As things start to oscillate too slowly, does the integrity of all matter start to change?? Would the atoms/molecules that made up the spaceship traveling at that extreme speed (and our bodies) begin to disintegrate??
> 
> Well, now we've gone and hijacked the thread into oblivion, but it was an interesting thought process.


1. The same physics that cause the clock's atomic oscillations also effect the atomic level processes in the body and all matter exposed the the same conditions.

2. In theory nothing abnormal happens to the matter traveling at such extremes. Only the emergence of the process we call "time" changes relative to an observer on a different trajectory.


----------



## BrianBinFL

dwalby said:


> I disagree with your other comment that someone at altitude will "experience more passage of time" during a solar orbit than you will at sea level, they will have simply experienced slightly more atomic oscillations than you did during that same interval. Roughly similar to the concept of your watch being a second per year slower than the other person's watch, all that was different was the perception of time measurement based on an arbitrary reference standard.


Well, you don't disagree with me so much as you disagree with Einstein. I don't really have an opinion one way or the other. I'm just parroting what I've read regarding his theories and regarding NIST believing they've proven Einstein right once again.

But I think it is a fair question to ask - has NIST proven that time dilation occurs the closer you get to a massive object with a strong gravitational field, or have they simply proven that an aluminum atom oscillates faster the further it is removed from such a field?

Despite all of our technology our ability to measure "time" is still indirect - using some process as a reference. So how do we know if a given situation has dilated time or simply altered the operation of the time keeping device?

Nonetheless the theory is that it is actual dilation of time itself and the scientific community seems to feel pretty confident that they have proven time and time again that the time dilation effect exists, so I'm willing to accept that absent information to the contrary.

As a side note, I found the Wikipedia article on time dilation to be interesting.



dwalby said:


> Within our limits of technology we'll probably never travel fast enough for those atomic oscillations to change by any appreciable amount, but let's just assume for a moment that we could. That brings up two interesting questions:
> 
> 1. As things start oscillating significantly more slowly, does the human body age any differently as a result? And if it changes, would we age faster, or slower?? To me that's the only practical application of time dilation taken to the extreme.
> 
> 2. As things start to oscillate too slowly, does the integrity of all matter start to change?? Would the atoms/molecules that made up the spaceship traveling at that extreme speed (and our bodies) begin to disintegrate??


I think that's the important thing - local to the person experiencing the dilation everything is the same. The differential is only the perception between the dissimilarly situated persons. Either the person at rest relative to the person at velocity, or the person closer to the gravitational field relative to the person further from the gravitational field.

I don't mean to act like I have a great grasp on all this. When you start playing with time it begins to be very difficult to keep a good grasp on things because once time is not constant nothing seems like it can be trusted anymore.

Quantum entanglement is another thing that bends my brain. Apparently it bothered Einstein as well - he referred to it as "spooky action at a distance". But that's a whole different topic and as you noted, we've already jacked this thread far into left field.

Fun to think about anyway. If the book yields anything poignant on the topic I'll share.


----------



## mleok

dwalby said:


> I disagree with your other comment that someone at altitude will "experience more passage of time" during a solar orbit than you will at sea level, they will have simply experienced slightly more atomic oscillations than you did during that same interval. Roughly similar to the concept of your watch being a second per year slower than the other person's watch, all that was different was the perception of time measurement based on an arbitrary reference standard.


You clearly have not heard of the twin paradox and lack even a basic understanding of special relativity. The number of atomic oscillations will correctly measure the passage of proper time.


----------



## gychang03

dwalby said:


> For example, if we define one year as the time it takes for the Earth to orbit the Sun, then it makes no sense to me that higher elevations of the Earth would complete that orbit any faster/slower than any other elevation on Earth.
> 
> Similarly, if I build an electronic timer with an incredibly stable oscillator, and the timer has something like ns or ps accuracy, what would cause it to run at different speeds as a function of elevation (assume the oscillator doesn't vary as a function of gravity, which I know does change slightly as a function of elevation).
> 
> If these questions are addressed in the book, let me know what the author says about it when you get to that part of the book.


First, sorry for throwing this thread completely off topic.

The time dilation conversation is one of relativity (one object with respect to the other..one object compared to another.. one object relative to another). That is, time is different for different observers. To each though, the super accurate clock is accurate. always. Each clock keeps time perfectly to the observer thats nearby it, or traveling with it. It's only when you compare the two clocks that you'll see a difference. The difference comes from gravity's effect on the space-time continuum. In this conversation, higher velocity = higher gravity, and low elevation on earth = higher gravity. the higher the gravity, the slower time the time will appear to someone who's in a lower gravitational field. It's only when comparing the two that you'll see the difference.

One year around the sun is defined as a year... higher elevation doesn't matter in this case b/c we are all on earth (relatively close) traveling at the same speed so it works out perfectly. We are all moving together (no one to compare to except astronauts and satellites.. which we'll get to)

This however, doesn't really effect our timekeeping of SDs with atomic clocks b/c the differences are sooooo tiny that we'll never realize it in a practical way when dealing with wrist watches. For GPS satellites however, it matters immensely b/c they are traveling so fast (high gravity) that they have to compensate for it daily.

When dealing with pendulum clocks, the elevation mattered a lot. Up in the Swiss mountains the pendulum could be calibrated but once you move the clock to sea level, it's no longer calibrated. This is no longer a special relativity thing though, this is now a newtonian (based on issac newton) physics thing. F=ma type thing where a=acceleration and acceleration is dependent on gravity's pull.

For the wrist watches, the effects of gravity shouldn't be observable to us... it'll easily be overcome by friction of the gears and such.


----------



## Jostack

Google says velocity does not effect gravity


----------



## mleok

I think there a bit of conflating the special and general theory of relativity going on here.


----------



## Jostack

mleok said:


> I think there a bit of conflating the special and general theory of relativity going on here.


Agree.

Besides, none of this has anything to do with accuracy of spring drive. An interesting conversation for sure, but it's too easy to mis-state and conflate and mis-interpretate the ideas proposed on a forum like this.


----------



## mleok

Jostack said:


> Agree.
> 
> Besides, none of this has anything to do with accuracy of spring drive. An interesting conversation for sure, but it's too easy to mis-state and conflate and mis-interpretate the ideas proposed on a forum like this.


I think the relevant aspect of the theory of relativity is that the notion of a universal time independent of the observer is debunked. In particular, whether two events are simultaneous is observer dependent.


----------



## Jostack

mleok said:


> I think the relevant aspect of the theory of relativity is that the notion of a universal time independent of the observer is debunked. In particular, whether two events are simultaneous is observer dependent.


I agree. It still has nothing to do with spring drive.

Time is a wa wa weird idea. Watches make it cool.


----------



## gychang03

Jostack said:


> Google says velocity does not effect gravity


Sorry, what I was saying was a bit simplified to get the point across (higher relative velocity slows down time)... velocity actually effects the inertial mass, or energy, which in the theory of relativity is the same as gravitational mass.

but... we are way off topic.

Back to Spring Drives. Does anyone know if 25C is the temperature the crystals oscillate fastest at? this is from brianbinfl's post on page 9


----------



## GMT-man

gychang03 said:


> Sorry, what I was saying was a bit simplified to get the point across (higher relative velocity slows down time)... velocity actually effects the inertial mass, or energy, which in the theory of relativity is the same as gravitational mass.
> 
> but... we are way off topic.
> 
> Back to Spring Drives.


What I have learned here is that instead of wearing my SD putting it under the bed for the night might fix the tendency of running 0.15 SPY? Yes?


----------



## Jostack

GMT-man said:


> What I have learned here is that instead of wearing my SD putting it under the bed for the night might fix the tendency of running 0.15 SPY? Yes?


As long as you are planning on sleeping for 4 million years.


----------



## gychang03

GMT-man said:


> What I have learned here is that instead of wearing my SD putting it under the bed for the night might fix the tendency of running 0.15 SPY? Yes?


What's SPY? if your watch is running just a bit slow and you're wearing it at night it may benefit from being taken off. if your watch is running a bit fast and you're wearing it at night, then you're outta luck. this is assuming our assumption about 25C being at the top of the parabola is correct.


----------



## BrianBinFL

gychang03 said:


> What's SPY? if your watch is running just a bit slow and you're wearing it at night it may benefit from being taken off. if your watch is running a bit fast and you're wearing it at night, then you're outta luck. this is assuming our assumption about 25C being at the top of the parabola is correct.


SPY is Seconds Per Year. Typically used when referring to the accuracy of High Accuracy Quartz (HAQ) watches.

The Grand Seiko 9F HAQ watches are thermo-compensated, so they aren't going to follow the behavior that we've been discussing for Spring Drive (which is not thermo-compensated).


----------



## gychang03

BrianBinFL said:


> I found my bead wire thermocouple and hooked it to the digital thermometer. I put the little stick thermocouple between my wrist and a solid-caseback watch and measured the temperature until it stopped going up. The reading stopped rising at 35.9° C. While this is not the 37° C that I used in my earlier calculations I think it's a lot higher than most here probably expected it would be. Unless you wear your watch loose it makes sense that most of your body heat will be trapped by the watch and therefore be similar to the thermometer in the armpit mentioned previously.


To add to this... I took a laser thermometer to my watch after wearing it for a few hours and then throughout the day. Highest reading on the face and back of the watch was 83.5F or 28.6C. Wrist temp was 85.5F or 29.7C where the watch was. My watch is currently running about 1 second fast a week. I'm going to try and wear it more often to keep it at higher than 25C to see if it slows it down. Also... Found some info about time.gov today.. added to the other thread about GPS clocks.


----------



## MegaloMajik

How accurate?
-Very


----------



## koolpep

My GS SBGA283 has gained 10 seconds in the last 2 months. I like that. In the watch box and worn once or twice a week.


----------



## DVR

SBGA071 from 2012, bought last month as NOS from AD.
Timed for one month and a day; gained a whole 2.5 seconds in that period.
Rotated with 2 other SD watches during that period.


----------



## Sassi

Here is a little update again. For the past week I have not worn my SBGA283, just kept it wound in the box. During this week it has been +0.2 sec/day.









Merry Christmas everyone! :-!


----------



## whineboy

Sassi said:


> Here is a little update again. For the past week I have not worn my SBGA283, just kept it wound in the box. During this week it has been +0.2 sec/day.
> 
> Merry Christmas everyone! :-!


Interesting, thanks. My 7R87A handwound SD also gains about 0.2 s/d and it's an older movement design.










I'm curious, did something happen in the last week or so to show a big increase in daily rate?

Happy holidays!

whineboy

All mechanical, all the time


----------



## Sassi

whineboy said:


> Interesting, thanks. My 7R87A handwound SD also gains about 0.2 s/d and it's an older movement design.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I'm curious, did something happen in the last week or so to show a big increase in daily rate?
> 
> Happy holidays!
> 
> whineboy
> 
> All mechanical, all the time


Beautiful watch! I stopped wearing it. On the wrist when temperature of the quartz crystal is higher the watch runs almost spot on from day to day. But when the watch is only room temperature it seems to be about +0.2 sec/day. It seems other owners are reporting similar results.


----------



## BrianBinFL

Sassi said:


> Here is a little update again. For the past week I have not worn my SBGA283, just kept it wound in the box. During this week it has been +0.2 sec/day.


Yep, that's about spot on for a Spring Drive at rest at room temperature. The +0.2 SPD number comes up so often I have to believe that's the number Grand Seiko sets them to so as to have a little "room" for time spent at temperatures above or below room temperature to bring it down toward +0.0.



whineboy said:


> Interesting, thanks. My 7R87A handwound SD also gains about 0.2 s/d and it's an older movement design.


Sounds like maybe the policy of setting Spring Drive movements at +0.2 SPD at room temperature (assuming such a policy actually exists) was established at the outset - so would be true for older movements and newer movements. Since the movement is self-regulating whatever they set it to is where it should run if it is at rest at 25º C, absent damage.



whineboy said:


> I'm curious, did something happen in the last week or so to show a big increase in daily rate?


He went from wearing it to not wearing it and now it's lonely. ;-) That and it's spending all of its time at or near room temperature.



Sassi said:


> I stopped wearing it. On the wrist when temperature of the quartz crystal is higher the watch runs almost spot on from day to day. But when the watch is only room temperature it seems to be about +0.2 sec/day. It seems other owners are reporting similar results.


|>

Merry Christmas to the Christians. Merry Holiday to the Pastafarians. Happy Holidays to everyone else whose winter holiday I'm not as familiar with.


----------



## indygreg

eblackmo said:


> Is it weird that I don't care about the accuracy of any of my watches? Unless it is noticeably losing or gaining seconds. It's not something I think about. Is there something wrong with me? Just about everyone else on WUS seems to be obsessed with it.
> 
> Also do you guys have timing machines? I have always wondered what methods people use to measure accuracy.


I have never cared unless it's bad enough to make me late. I view watches more as art than a time keeping tool. The phone keeps great time.


----------



## dwalby

Sassi said:


> Beautiful watch! I stopped wearing it. On the wrist when temperature of the quartz crystal is higher the watch runs almost spot on from day to day. But when the watch is only room temperature it seems to be about +0.2 sec/day. It seems other owners are reporting similar results.


yeah, the temperature dependency of quartz oscillators becomes noticeable when measuring accuracy of a few seconds per month or less. Some quartz are temperature compensated, but that doesn't always work perfectly and the rate will still change slightly over temp.


----------



## FishingForFishies

I read through this thread before I purchased my A375. Really interesting to see what everyone has figured out. 

Started a timing run on my watch and while I only have a few data points, they show the watch running at +0.2 seconds a day. 

I think it’s really interesting that had I not come across this thread, maybe I’d think the watch could be more accurate. But now, I know that actually it’s running ‘perfect’ as intended. 


Sent from my iPhone using Tapatalk


----------



## gychang03

Hi All,
Came across this omega video where they use 33 degrees C as the wrist temp for their testing. Made me think about the conversations about the parabolic profile of the spring drive accuracy we discussed a few months back.

starts at the 5:10 mark.








The Omega Master Chronometer Certification - Our Video Documentary Inside the Manufacture


Going Where No Camera Has Gone Before - Our TV-Style Documentary About The Omega Master Chronometer Certification and a Visit of the Facilities




monochrome-watches.com


----------



## matthew P

As a data point mine was running approx +0.3 before a movement service that required some repairs. 
It came back still running 0.3 after the repair as stated on the repair slip where they use a quartz accuraccy testing machine.










I find it interesting that the accuracy was so similar before and after service. 
Makes me think the regulator/ braking is doing a lot of the heavy lifting accuracy wise.

•• sent by two turn tables and a microphone ••


----------



## bombaywalla

matthew P said:


> As a data point mine was running approx +0.3 before a movement service that required some repairs.
> It came back still running 0.3 after the repair as stated on the repair slip where they use a quartz accuraccy testing machine.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I find it interesting that the accuracy was so similar before and after service.
> *Makes me think the regulator/ braking is doing a lot of the heavy lifting accuracy wise.*
> 
> •• sent by two turn tables and a microphone ••


If you understand how SD works, the accuracy is not done, per se, by the regulator/braking. The regulator/braking is the acuation part. The accuracy is controlled by the quartz crystal, always. The SD accuracy is as good as the quartz crystal; no better. the controller IC determines whether more or less braking is needed, that command is fed to the braking mechanism & the electro-motive force is either increased or decreased to either slow down the glide wheel or speed it up respectively to maintain the said accuracy. EMF braking is always present as long as the watch is running. 
Go back to some of the initial posts in this thread & read up some more on how SD works - BrianBinFL has done a super job in helping to explain & also given links to many GS patents related to SD. worth reading & educating yourself....


----------



## SolarPower

I came late, but enjoy this thread very much. Thanks to all the contributors and esp. to BrianBinFL !

I found it really interesting that quartz frequency to temperature curve is so symmetric around regulated zero point. Hard to believe, so would appreciate a link to where this chart came from in a hope to see some reasons behind it.


----------



## BrianBinFL

SolarPower said:


> I came late, but enjoy this thread very much. Thanks to all the contributors and esp. to BrianBinFL !
> 
> I found it really interesting that quartz frequency to temperature curve is so symmetric around regulated zero point. Hard to believe, so would appreciate a link to where this chart came from in a hope to see some reasons behind it.
> View attachment 15518950


I found that graphic originally by doing a Google image search for quartz oscillator parts per million frequency deviation, or something like that. It's not a chart specifically for the GS quartz crystals. It's a chart for a typical tuning fork shaped quartz crystal with a -0.04 PPM frequency deviation based upon temperature.

Once upon a time I considered working out the PPM for the Spring Drive oscillator by leaving the watch to run in a temperature controlled environment significantly above or below the center point, at various temperatures, measuring the effect upon the accuracy, and then backing into the PPM to produce a chart like that. But then my laziness kicked in. Lol.


----------



## SolarPower

BrianBinFL said:


> I found that graphic originally by doing a Google image search for quartz oscillator parts per million frequency deviation, or something like that. It's not a chart specifically for the GS quartz crystals. It's a chart for a typical tuning fork shaped quartz crystal with a -0.04 PPM frequency deviation based upon temperature.
> 
> Once upon a time I considered working out the PPM for the Spring Drive oscillator by leaving the watch to run in a temperature controlled environment significantly above or below the center point, at various temperatures, measuring the effect upon the accuracy, and then backing into the PPM to produce a chart like that. But then my laziness kicked in. Lol.


Yeah, nothing substitutes real life experiment  Making closely controlled temperature environment might present certain challenges, although perhaps and ,if we trust the chart you found, within a degree difference should be acceptable

The chart sure looks very theoretical and although I do not doubt it overall, real quartz might deviate from this perfect curve. I will Google a bit..


----------



## bombaywalla

SolarPower said:


> Yeah, nothing substitutes real life experiment  Making closely controlled temperature environment might present certain challenges, although perhaps and ,if we trust the chart you found, within a degree difference should be acceptable
> 
> The chart sure looks very theoretical and although I do not doubt it overall, real quartz might deviate from this perfect curve. I will Google a bit..


SolarPower, look in this thread where Brian posted another more realistic curve of different crystal cuts vs temp. The plot has AT-cut, XY-cut, GT-cut, etc, etc. Some 6 diff cuts vs temp. THAT plot looks like real data taken & plotted.
The above plot you re-showed is probably correct but looks like straight out of a text book where the publisher makes the plots pretty for the sake of the reader (nature of the textbook business)...


----------



## SolarPower

Ok. To follow up, I found a good albeit again a theoretical article which is confirming what Brian has posted here


https://apps.dtic.mil/dtic/tr/fulltext/u2/a248503.pdf



From there it is interesting to see that the frequency shift due to the variation of temperature can be expressed in a cubic curve of the form:

Df/f0 = a0(T - T0) + b0(T - T0)**2 + c0(T - T0)**3

Here goes the more detailed info








And this is how a watch oscillator is affected by the temperature change in seconds per day.








It still is quite theoretical, but I think between all the already posted ones it provides the final numbers directly.

Failed to find any experimental curve so far.


----------



## bombaywalla

SolarPower
in this very thread look at post #95 by "gychang03" that shows the Freq-vs-Temp profile of various crystal cuts -- it looks like expt data.
I'm re-posting here for convenience (plot courtesy gychang03)


----------



## SolarPower

Yes, thanks.


----------



## Bernardo de Carvalho

@BrianBinFL how did you end up with a SBGA373 and a SBGH273 any particular thing you appreciate about those two models? Thanks in advance.


----------



## BrianBinFL

Bernardo de Carvalho said:


> @BrianBinFL how did you end up with a SBGA373 and a SBGH273 any particular thing you appreciate about those two models? Thanks in advance.


How I ended up with an SBGA373 and an SBGH273 is a rather long and painful story, but I'll give you the short version here.

My first GS was an SBGA375 (44GS case, midnight blue dial). When I bought it I was torn as to whether I made a mistake and should have gotten the SBGA373 (same watch but with champagne dial). When I got my second GS it was the SBGA373.

A couple years later I noticed some corrosion on one of the indices of my SBGA375. It was under warranty so I sent it in. I let Mahwah service it. This was a mistake. Without going into a ton of detail like I usually do, when the SBGA375 came back it was no longer a timepiece I could bear to own due to their mistreatment. Yes, they replaced the dial, but the new dial had flaws and the formerly pristine case of the watch was now covered in scratches.

I should have fought with Seiko and made them make it right, but it happened at a time when I didn't have the emotional reserves to deal with it.

I could have sold the damaged SBGA375 and bought another one, and eaten thousands of dollars in loss in the deal, but I knew I would never be able to look at the new SBGA375 without remembering what happened and resenting it.

I decided that if I was going to ditch the watch that was now dead to me, and spend thousands of dollars getting another, it should be something different that could exist in its own right. Something similar but different. The SBGH273 fit the bill. Still a blue dial, but a different blue dial. Still a very attractive case but a 62GS instead of a 44GS. Instead of a Spring Drive movement it has the Hi-Beat 36000.

Candidly at first I did not bond with the SBGH273. I kept comparing it to the SBGA375 and focusing on the ways that it was different. To solve that I just started wearing it a lot. And I soon stopped trying to have it fill the shoes of the SBGA375. Now I like the watch very much. I will probably buy another SBGA375 someday, but for now I am satisfied.

I don't know if that answers your question.

My apologies to the OP of the thread for the diversion - but the thread was old and idle so I saw no harm in replying inline.


----------



## Bernardo de Carvalho

@BrianBinFL that's an interesting story and also relevant to know the service issues you faced.

I have the exact same two models. My SBGA373 went for service and returned recently with some issues. Fortunately nothing that affetcs the accuracy - that is working great.

I also suffer from the same dilema. The problem is that Grand Seiko makes many great models and it's hard to choose the right one.

I was always stalking the snowflake (SBGA211) but when the AD showed me the sunray (SBGA373) it was an automatic buy. Couple months ago I was in New York and decided to go to the Grand Seiko Boutique spent sometime deciding between the SLGH003 and the SBGH273. I still don't know if I made the right choice but this modern 62GS design is beautiful.


----------



## Drebs

I have 2 GS, an SBGE257 and an SBGA229. The 257 is +1 over 3 weeks. I haven't tracked the 229.


----------



## jkpa

Mine is very consistent at +0.2 spd


----------



## Shiny-Lights

interesting thread, I have an older snowflake running at +0.5 per month


----------



## BrianBinFL

Fair warning - this post is REALLY long. If you don't care about the temperature coefficient of quartz oscillators, and things of that nature, skip this post.

I recently added an SBGA375 back into to my collection. Whenever I buy a new watch I always to a precise sync check on it to see how good the accuracy is. Being that the A375 is a Spring Drive watch I ended up delving back into some of the topics we've examined along the way in this thread.

In an earlier post in this thread I posted this graph:









In that post I acknowledged that we have no way of knowing if the frequency/temperature response of the oscillator Grand Seiko uses in the Spring Drive is -0.04 PPM/°C². After looking at various oscillator manufacturers it appears that -0.04 PPM/°C² is VERY common for the XY cut (tuning fork) quartz oscillators. Here is a link to the spec sheet for the tightest tolerance 32,768 Hz XY cut quartz oscillator by a certain manufacturer, and, like every 32,768 Hz XY cut quartz oscillator whose spec sheet I reviewed, the temperature coefficient was -0.04 PPM/°C².

But of course Grand Seiko makes their own oscillators, so whatever is common in the industry may not mean much. Then again, physics is physics, and if you need a slice of quartz cut to a certain size and shape to make a tuning fork oscillator that vibrates at 32,768 Hz, it stands to reason that they will all behave in a similar manner.

So I decided to try to do a test to see if Grand Seiko's oscillators match this spec.

In my house I keep my office at about 21.5 °C for about 18 hours a day, and at about 23.5 °C for about 6 hours a day. The office is kept quite a bit colder than the rest of the house due to a thermal incompatibility with the wife.

I've been keeping the A375 in the office while I do the sync test because: a) that's where the watchmaker's workbench and one of my GPS clocks are, b) I'll see it every day when I begin work and that reminds me to wind it periodically and do a video sync check against the GPS clock periodically.

I don't have an exact map of the temperatures in the room and have just assumed 21.5 °C for 18 hours a day, and 23.5 °C for 6 hours a day. The office has its own climate control, and the temperature adjustment is on an automated schedule, so those values should be reasonably reliable.

Obviously there is a slope in the temperature at the transitions, but for the purposes of the experiment I assume the decreasing temperature and increasing temperature profiles cancel each other out, allowing the aforementioned assumption.

Using the video method I observed that over 8.093 days the A375 gained 1.2 seconds. That's 0.1483 seconds per day. This is actually quite a bit better than the usual observation of 0.18 seconds per day or so. But that would stand to reason since the watch is being kept in a room that is significantly cooler than the 25 °C turnover temperature (the peak of the parabola).

For those of you just tuning in, with a tuning fork (XY cut) quartz crystal, it is generally at spec (32,768 Hz) at 25 °C, which is treated as "room temperature". This is the peak of the parabola in the chart above, and is called the "turnover temperature". If the temperature is higher than 25 °C the frequency of the crystal slows down. If the temperature is lower than 25 °C the frequency of the crystal slows down. Environmentally there's nothing you can do the crystal to make it run faster than the spec frequency. Any deviation from the turnover temperature results in it running slower.

So I made a spreadsheet to do the math of what the effect would be on oscillator frequency for the watch remaining at certain temperatures for certain lengths of time each day. The watch was never on-body. Presumably after enough hours at a given temperature every component of the watch will reach that temperature. Just like the room temperature will be a slope as it transitions from the 18-hours-per-day temperature to the 6-hours-per-day temperature, so will the temperature of the watch, but again, presumably the up slope and down slope cancel each other and you can treat it as though the watch actually spends that number of hours at each temperature.









I had to make an assumption about what the built in factory error is, so I chose +0.18 seconds per day as this is the value spied momentarily in a Grand Seiko video. There's no guarantee that this is the exact built in error for this watch, and it's reasonable to assume that it could vary from watch to watch.

This value could actually be observed by keeping the watch at 25 °C for a week or so and measuring the error, but that's a little hard for me as there's no place in the house that stays that hot, nor consistently so.

Anyway, assuming a 25 °C turnover temperature, a temperature coefficient of -0.04 PPM/°C², and a deliberate bias of +0.18 seconds per day, the expected observed error per day (after the effect of the temperature) worked out to 0.1463 seconds per day.

As mentioned earlier in this insanely long post, my actual observation was 0.1483 seconds per day. That's pretty darn close - a difference of a couple thousandths of a second per day.

In order to be convinced that the temperature coefficient actually is -0.04 PPM/°C² I need a second data point. I've moved the watch out of the office, to a part of the house that is 24 °C for 18 hours a day, and 25.5 °C for 6 hours a day. In about 6 days I'll do a video sync check, see what the gain has been, and repeat the math.


----------



## BrianBinFL

Shiny-Lights said:


> interesting thread, I have an older snowflake running at +0.5 per month


Very nice!

That'd be about +0.166 seconds per day, which would be about what I'd expect for a Spring Drive movement that is kept a few degrees C above or below room temperature for 10 hours a day, or any number of other combinations of temperatures and durations.


----------



## whineboy

BrianBinFL said:


> Fair warning - this post is REALLY long. If you don't care about the temperature coefficient of quartz oscillators, and things of that nature, skip this post.
> 
> I recently added an SBGA375 back into to my collection. Whenever I buy a new watch I always to a precise sync check on it to see how good the accuracy is. Being that the A375 is a Spring Drive watch I ended up delving back into some of the topics we've examined along the way in this thread.
> 
> In an earlier post in this thread I posted this graph:
> View attachment 16858140
> 
> 
> In that post I acknowledged that we have no way of knowing if the frequency/temperature response of the oscillator Grand Seiko uses in the Spring Drive is -0.04 PPM/°C². After looking at various oscillator manufacturers it appears that -0.04 PPM/°C² is VERY common for the XY cut (tuning fork) quartz oscillators. Here is a link to the spec sheet for the tightest tolerance 32,768 Hz XY cut quartz oscillator by a certain manufacturer, and, like every 32,768 Hz XY cut quartz oscillator whose spec sheet I reviewed, the temperature coefficient was -0.04 PPM/°C².
> 
> But of course Grand Seiko makes their own oscillators, so whatever is common in the industry may not mean much. Then again, physics is physics, and if you need a slice of quartz cut to a certain size and shape to make a tuning fork oscillator that vibrates at 32,768 Hz, it stands to reason that they will all behave in a similar manner.
> 
> So I decided to try to do a test to see if Grand Seiko's oscillators match this spec.
> 
> In my house I keep my office at about 21.5 °C for about 18 hours a day, and at about 23.5 °C for about 6 hours a day. The office is kept quite a bit colder than the rest of the house due to a thermal incompatibility with the wife.
> 
> I've been keeping the A375 in the office while I do the sync test because: a) that's where the watchmaker's workbench and one of my GPS clocks are, b) I'll see it every day when I begin work and that reminds me to wind it periodically and do a video sync check against the GPS clock periodically.
> 
> I don't have an exact map of the temperatures in the room and have just assumed 21.5 °C for 18 hours a day, and 23.5 °C for 6 hours a day. The office has its own climate control, and the temperature adjustment is on an automated schedule, so those values should be reasonably reliable.
> 
> Obviously there is a slope in the temperature at the transitions, but for the purposes of the experiment I assume the decreasing temperature and increasing temperature profiles cancel each other out, allowing the aforementioned assumption.
> 
> Using the video method I observed that over 8.093 days the A375 gained 1.2 seconds. That's 0.1483 seconds per day. This is actually quite a bit better than the usual observation of 0.18 seconds per day or so. But that would stand to reason since the watch is being kept in a room that is significantly cooler than the 25 °C turnover temperature (the peak of the parabola).
> 
> For those of you just tuning in, with a tuning fork (XY cut) quartz crystal, it is generally at spec (32,768 Hz) at 25 °C, which is treated as "room temperature". This is the peak of the parabola in the chart above, and is called the "turnover temperature". If the temperature is higher than 25 °C the frequency of the crystal slows down. If the temperature is lower than 25 °C the frequency of the crystal slows down. Environmentally there's nothing you can do the crystal to make it run faster than the spec frequency. Any deviation from the turnover temperature results in it running slower.
> 
> So I made a spreadsheet to do the math of what the effect would be on oscillator frequency for the watch remaining at certain temperatures for certain lengths of time each day. The watch was never on-body. Presumably after enough hours at a given temperature every component of the watch will reach that temperature. Just like the room temperature will be a slope as it transitions from the 18-hours-per-day temperature to the 6-hours-per-day temperature, so will the temperature of the watch, but again, presumably the up slope and down slope cancel each other and you can treat it as though the watch actually spends that number of hours at each temperature.
> 
> View attachment 16858200
> 
> I had to make an assumption about what the built in factory error is, so I chose +0.18 seconds per day as this is the value spied momentarily in a Grand Seiko video. There's no guarantee that this is the exact built in error for this watch, and it's reasonable to assume that it could vary from watch to watch.
> 
> This value could actually be observed by keeping the watch at 25 °C for a week or so and measuring the error, but that's a little hard for me as there's no place in the house that stays that hot, nor consistently so.
> 
> Anyway, assuming a 25 °C turnover temperature, a temperature coefficient of -0.04 PPM/°C², and a deliberate bias of +0.18 seconds per day, the expected observed error per day (after the effect of the temperature) worked out to 0.1463 seconds per day.
> 
> As mentioned earlier in this insanely long post, my actual observation was 0.1483 seconds per day. That's pretty darn close - a difference of a couple thousandths of a second per day.
> 
> In order to be convinced that the temperature coefficient actually is -0.04 PPM/°C² I need a second data point. I've moved the watch out of the office, to a part of the house that is 24 °C for 18 hours a day, and 25.5 °C for 6 hours a day. In about 6 days I'll do a video sync check, see what the gain has been, and repeat the math.


I’m just delighted to hear you are again enjoying an SBGA375! 


Having a great time….


----------



## BrianBinFL

whineboy said:


> I’m just delighted to hear you are again enjoying an SBGA375!


Thanks. I'm pretty sure you and I chatted privately about it when it all happened. I am very happy to have an A375 again. I love my H273, but it never fully filled the void.


----------



## bombaywalla

BrianBinFL said:


> Fair warning - this post is REALLY long. If you don't care about the temperature coefficient of quartz oscillators, and things of that nature, skip this post.
> 
> I recently added an SBGA375 back into to my collection. Whenever I buy a new watch I always to a precise sync check on it to see how good the accuracy is. Being that the A375 is a Spring Drive watch I ended up delving back into some of the topics we've examined along the way in this thread.
> 
> In an earlier post in this thread I posted this graph:
> View attachment 16858140
> 
> 
> In that post I acknowledged that we have no way of knowing if the frequency/temperature response of the oscillator Grand Seiko uses in the Spring Drive is -0.04 PPM/°C². After looking at various oscillator manufacturers it appears that -0.04 PPM/°C² is VERY common for the XY cut (tuning fork) quartz oscillators. Here is a link to the spec sheet for the tightest tolerance 32,768 Hz XY cut quartz oscillator by a certain manufacturer, and, like every 32,768 Hz XY cut quartz oscillator whose spec sheet I reviewed, the temperature coefficient was -0.04 PPM/°C².
> 
> But of course Grand Seiko makes their own oscillators, so whatever is common in the industry may not mean much. Then again, physics is physics, and if you need a slice of quartz cut to a certain size and shape to make a tuning fork oscillator that vibrates at 32,768 Hz, it stands to reason that they will all behave in a similar manner.
> 
> So I decided to try to do a test to see if Grand Seiko's oscillators match this spec.
> 
> In my house I keep my office at about 21.5 °C for about 18 hours a day, and at about 23.5 °C for about 6 hours a day. The office is kept quite a bit colder than the rest of the house due to a thermal incompatibility with the wife.
> 
> I've been keeping the A375 in the office while I do the sync test because: a) that's where the watchmaker's workbench and one of my GPS clocks are, b) I'll see it every day when I begin work and that reminds me to wind it periodically and do a video sync check against the GPS clock periodically.
> 
> I don't have an exact map of the temperatures in the room and have just assumed 21.5 °C for 18 hours a day, and 23.5 °C for 6 hours a day. The office has its own climate control, and the temperature adjustment is on an automated schedule, so those values should be reasonably reliable.
> 
> Obviously there is a slope in the temperature at the transitions, but for the purposes of the experiment I assume the decreasing temperature and increasing temperature profiles cancel each other out, allowing the aforementioned assumption.
> 
> Using the video method I observed that over 8.093 days the A375 gained 1.2 seconds. That's 0.1483 seconds per day. This is actually quite a bit better than the usual observation of 0.18 seconds per day or so. But that would stand to reason since the watch is being kept in a room that is significantly cooler than the 25 °C turnover temperature (the peak of the parabola).
> 
> For those of you just tuning in, with a tuning fork (XY cut) quartz crystal, it is generally at spec (32,768 Hz) at 25 °C, which is treated as "room temperature". This is the peak of the parabola in the chart above, and is called the "turnover temperature". If the temperature is higher than 25 °C the frequency of the crystal slows down. If the temperature is lower than 25 °C the frequency of the crystal slows down. Environmentally there's nothing you can do the crystal to make it run faster than the spec frequency. Any deviation from the turnover temperature results in it running slower.
> 
> So I made a spreadsheet to do the math of what the effect would be on oscillator frequency for the watch remaining at certain temperatures for certain lengths of time each day. The watch was never on-body. Presumably after enough hours at a given temperature every component of the watch will reach that temperature. Just like the room temperature will be a slope as it transitions from the 18-hours-per-day temperature to the 6-hours-per-day temperature, so will the temperature of the watch, but again, presumably the up slope and down slope cancel each other and you can treat it as though the watch actually spends that number of hours at each temperature.
> 
> View attachment 16858200
> 
> I had to make an assumption about what the built in factory error is, so I chose +0.18 seconds per day as this is the value spied momentarily in a Grand Seiko video. There's no guarantee that this is the exact built in error for this watch, and it's reasonable to assume that it could vary from watch to watch.
> 
> This value could actually be observed by keeping the watch at 25 °C for a week or so and measuring the error, but that's a little hard for me as there's no place in the house that stays that hot, nor consistently so.
> 
> Anyway, assuming a 25 °C turnover temperature, a temperature coefficient of -0.04 PPM/°C², and a deliberate bias of +0.18 seconds per day, the expected observed error per day (after the effect of the temperature) worked out to 0.1463 seconds per day.
> 
> As mentioned earlier in this insanely long post, my actual observation was 0.1483 seconds per day. That's pretty darn close - a difference of a couple thousandths of a second per day.
> 
> In order to be convinced that the temperature coefficient actually is -0.04 PPM/°C² I need a second data point. I've moved the watch out of the office, to a part of the house that is 24 °C for 18 hours a day, and 25.5 °C for 6 hours a day. In about 6 days I'll do a video sync check, see what the gain has been, and repeat the math.


@BrianBinFL 
Nice experiment…

I didn’t understand the column “cycles dev for time”. How was that calculated?
Thanks.


----------



## bombaywalla

@BrianBinFL 
Somethings not making sense here — the deviation is 0.01606Mhz which is 16.06khz of a 32.768khz xtal. That’s a massive deviation for 18 hrs & you lost only a few fractions of a second. 
maybe I’m not reading/understanding this correctly….


----------



## BrianBinFL

bombaywalla said:


> @BrianBinFL
> Somethings not making sense here — the deviation is 0.01606Mhz which is 16.06khz of a 32.768khz xtal. That’s a massive deviation for 18 hrs & you lost only a few fractions of a second.
> maybe I’m not reading/understanding this correctly….


I'll provide the formulas. In case I did something wrong. It's been a while since I did the PPM math on these things. But I'm pretty sure I did it right.

The "Hours" and "Temp C" columns are obvious, and are user (me) supplied data.

"PPM/°C²" is a constant, based upon the assumption of -0.04 PPM/°C².
"PPM Dev" (F6 and F7) is the PPM/°C² constant of -0.04 times the square of the temperature difference. =E6 * (D6-$D$2)^2 and =E7 * (D7-$D$2)^2
"MHz Dev" (G6 and G7) is the PPM Dev times the oscillator frequency in MHz. =F6*$D$3 and =F7*$D$3
"Cycles Dev for Time" (H6 and H7) is how may cycles of deviation will have occurred in the number of hours the room was at that temperature. =G6*60*60*C6 and =G7*60*60*C7
"Seconds Dev" (I6 and I7) is that number of cycles converted back into seconds by dividing by the oscillator frequency in Hz (not MHz). =H6/($D$3*1000000) and =H7/($D$3*1000000)
"Total seconds deviation for the day" (I9) is just the sum of the two values in column I. =SUM(I6:I7)
"Built in Spring Drive padding error seconds/day" (I11) is a constant which I have assumed to be 0.18 sec/day for now.
"Observed error/day should be" (I13) is the assumed constant minus the expected deviation due to temperature. =I11+I9
Yes, I realize there is some redundant math in there multiplying by the oscillator frequency in MHz and then later dividing by the oscillator frequency in Hz. But it's the same orderly progression I've used before that has checked out against some known examples, and I didn't want to modify it.

I think maybe the problem is that my MHz Dev column should be labeled Hz Dev? I think I got the right answer but just labeled column G wrong. 

Your feedback is welcome.


----------



## bombaywalla

BrianBinFL said:


> I'll provide the formulas. In case I did something wrong. It's been a while since I did the PPM math on these things. But I'm pretty sure I did it right.
> 
> The "Hours" and "Temp C" columns are obvious, and are user (me) supplied data.
> 
> "PPM/°C²" is a constant, based upon the assumption of -0.04 PPM/°C².
> 
> "PPM Dev" (F6 and F7) is the PPM/°C² constant of -0.04 times the square of the temperature difference. =E6 * (D6-$D$2)^2 and =E7 * (D7-$D$2)^2
> "MHz Dev" (G6 and G7) is the PPM Dev times the oscillator frequency in MHz. =F6*$D$3 and =F7*$D$3
> "Cycles Dev for Time" (H6 and H7) is how may cycles of deviation will have occurred in the number of hours the room was at that temperature. =G6*60*60*C6 and =G7*60*60*C7
> "Seconds Dev" (I6 and I7) is that number of cycles converted back into seconds by dividing by the oscillator frequency in Hz (not MHz). =H6/($D$3*1000000) and =H7/($D$3*1000000)
> "Total seconds deviation for the day" (I9) is just the sum of the two values in column I. =SUM(I6:I7)
> "Built in Spring Drive padding error seconds/day" (I11) is a constant which I have assumed to be 0.18 sec/day for now.
> "Observed error/day should be" (I13) is the assumed constant minus the expected deviation due to temperature. =I11+I9
> 
> Yes, I realize there is some redundant math in there multiplying by the oscillator frequency in MHz and then later dividing by the oscillator frequency in Hz. But it's the same orderly progression I've used before that has checked out against some known examples, and I didn't want to modify it.
> 
> I think maybe the problem is that my MHz Dev column should be labeled Hz Dev? I think I got the right answer but just labeled column G wrong.
> 
> Your feedback is welcome.
> 
> View attachment 16859192


Thanks for clarifying — I went back & did the math myself the old fashioned way - paper & pencil.

so, yes, your math is correct but one column — the one you wrote — is mis-labeled.
column G should be labeled “fractional deviation” because the deviation for the 32.768khz xtal is 0.01606 parts.
when you multiply 0.01606 parts by 32768hz you get frequency = 526hz (if I remember correctly — that piece of paper is in the kitchen & I’m not going back there again😄).

yes, then, number of cycles of deviation is 1040 & that does translate to 31.7 milli seconds per day.

yeah, just re-label column G as suggested above. Thanks.


----------



## BrianBinFL

bombaywalla said:


> Thanks for clarifying — I went back & did the math myself the old fashioned way - paper & pencil.
> 
> so, yes, your math is correct but one column — the one you wrote — is mis-labeled.
> column G should be labeled “fractional deviation” because the deviation for the 32.768khz xtal is 0.01606 parts.
> when you multiply 0.01606 parts by 32768hz you get frequency = 526hz (if I remember correctly — that piece of paper is in the kitchen & I’m not going back there again😄).
> 
> yes, then, number of cycles of deviation is 1040 & that does translate to 31.7 milli seconds per day.
> 
> yeah, just re-label column G as suggested above. Thanks.


Thanks for the validation Bombaywalla. I have updated the label for the column. The next time I post a data point (at the conclusion of the current experiment) you will see the label reads "Hz" instead of "MHz".


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## whineboy

BrianBinFL said:


> Thanks. I'm pretty sure you and I chatted privately about it when it all happened. I am very happy to have an A375 again. I love my H273, but it never fully filled the void.


Yep, we did. Glad you moved ahead with positivity (and your technical skills amaze).


Having a great time….


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## Wizardskills

I have two Spring Drives. My Snowflake is running at 0.2spd average while my SBGA461 is 0.0spd average. Impressive. I usually wear the 461 on the weekends, while the 211 is my work watch.


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