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Planning and lateral forethought in design are two elements present throughout much of Seiko’s wristwatch caliber production. If you aspire to make as many watches as Seiko does, you don’t get there by re-inventing the wheel for every caliber need. An example of this from the late 60’s is the 6139 automatic chronograph caliber, which was clearly based on the layout of the time and calendar-only 6106 and shared many major parts in common. This is smart engineering, because it also foresees after-sales service needs; stocking fewer parts to cover more calibers should be the aim of every manufacture, and Seiko does this well.

So does Seiko still practice this type of cross-pollination between calibers? A recent chance to service a newly acquired 6S78 Credor movement made it clear to me that this approach is still alive and well, between two streams of calibers we may not have suspected.

The 6S stream is a family of automatic and manual wind-only chronograph calibers, with various calendar/power reserve display options, and even a skeletonized version. See a nice table here, at watch-wiki.net: http://www.watch-wiki.net/index.php?title=Seiko_6S78

My example is inside a Credor Phoenix, a caliber 6S78 (automatic, date, no power reserve display). About a year ago, I had a conversation with a good friend and fellow collector about the basis of the 6S. Thinking about what little I knew of it [and a lot of that was from marketing material on Tag Heuer’s caliber 1887 ;-) ], I hypothesized that it could share a common ancestry with the 9S55, based on the location and design of the ratchet wheel, and the location and design of the pawl lever and transmission wheel next to it, under a sub-bridge. I couldn't see much else from photos so this was not exactly a lot to go on or enough to claim a clear connection, leaving me to keep my thoughts and suspicions to myself. At this point, I should also point out that the 9S and 8L streams are very much of the same lineage, with the apparent differences being the level of aesthetic finishing on the bridges and oscillating weight, and the adjustments made at the factory regarding time-keeping. There are more photos out there of 8L’s being disassembled than 9S’s, if you need to refresh yourself.

Well, flash-forward about a year to when this same collector I was conversing with earlier generously gave me an opportunity to acquire one of his 6S-watches, allowing me a great opportunity to find out where this caliber comes from, so to speak. Wanting to discover more, I did what any sane person would do- I took it apart!*

Below are several photos** that confirm to me the 6S chronograph is based on the 9S automatic caliber, which was also released in 1998 (coincidence? I think not!). While it lacks some of the surface finishing and painstaking adjustments and testing in 6 positions, it is still (in my opinion) as related to the 9S as the 8L is. So please enjoy, and if I somehow missed a meeting and everyone already knew this, still try to enjoy, and kindly point me to the previous discussion so that I can know once again I’m behind the curve- you won’t burst my balloon.

Take a deep breath, there’s a long way to getting back to this state:

The tool bit I made to remove the oscillating weight (the first movemenet part to be removed, otherwise no meaningful disassembly/servicing can be accomplished). I checked, but they didn't have any at the hardware store:

With the oscillating weight removed:

The dial side:

With the calendar plate and date dial removed. That large rocking bar mounted at 3 o'clock with 5 setting wheels beneath is pretty unique, and clearly shared by the 9S/8L. Same with the date jumper with integral spring tail:

Chronograph bridge removed:

Most of the chronograph parts removed. See the outside finger of the pawl lever laying on top of (disengaged with) the transmission wheel (at about 11:30 in the photo)?:

Underside of the train bridge, showing the pawl lever and permanently-mounted crown wheel:

Movement sans train bridge. Notice the silver-colored center wheel bridge- a unique design feature shared by the 9S where the center-mounted cannon pinion wheel rides on a post mounted to said bridge, such that the cannon pinion wheel’s teeth are on the bridge side of the mainplate, not the dial side as is tradition. I suspect the 9F might even do something similar, but that is a conversation for a different time! :

Showing the center wheel bridge flipped over, to see the post that the cannon pinion wheel rides upon:

Almost completely stripped! Notice the three tapped feet surrounding the balance jewel setting, at around 7:30 in the photo. We’ll talk about those later:

Barren dial side:

Now we’re getting into some shots taken during re-assembly. Here are the basic setting parts assembled, I suspect these are directly interchangeable with the 9S parts:

OK, remember those three threaded feet I mentioned? Here they are again, with the pallet fork installed where it is supposed to be, but with the pallet bridge a little…confused. Wrong feet, buddy!:

You see, the 9S, being a directly-driven center seconds caliber, has the train develop inwards from the balance, towards the center of the watch. The escape wheel is also moved over towards the middle of the mainplate, and the pallet fork accommodates this shift. So the mainplates are machined one way or the other, depending on which caliber is being produced. I suspect there was at least one sub-seconds caliber in the 9S/ 8L stream that would have used the layout that the 6S does. It is the 8L34 railroad pocket watch, with sub-seconds dial opposite the crown position, just like the continuously-running seconds hand is on the 6S stream. I liked seeing this type of flexibility being designed into the movement, and it further suggests that this whole family was developed concurrently. They clearly share several elements of design and layout, some that I noticed were the calendar and setting systems, the hand- and auto-winding systems, the basic train layout including the unique center bridge below (with obvious changes needing to be made to accommodate the sub-seconds at 9 and the chronograph complication), and the balance assembly and balance bridge shape/design (again with modifications to fit the chronograph parts above it).

I know of no other Seiko caliber streams that share these combinations of elements, suggesting that the 9S/8L/6S are uniquely and wonderfully linked.

Thanks for watching!
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* Trained, experienced, and practicing watchmaker, do not attempt at home. Not having parts access for this caliber, I understood the risks involved with servicing it myself and was ready to send it to Seiko Japan if there were parts that needed to be replaced.
** Most photos were taken during disassembly, so remnants of the previous lubrication are still present, as well as possibly other pieces of debris that were later removed during the cleaning process. While that makes for a sometimes-messy photo, I have found it allows me to better concentrate on the re-assembly and oiling tasks.
 

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Thank you for taking the time and making the effort for this interesting post Noah. Something interesting to read on SCWF for a change.

Being a 6139 freak this does reinforce my view what Seiko achieved with the 6139 in terms of simplicity and lateral design. I was thinking only yesterday how Seiko manage to create a chronograph from the base movements they initially produce, the 70XX is the same although not such a nice complication.
 

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Thank you very much for this great post, Noah. Very informative and explain many things. Now I know why my 6S37 Flightmaster was the most accurate non-GS automatic SEIKO in my collection! :D

That special tool for open the rotor, do you mind explain how you build it? That is what prevented my local SEIKO watchmaker to access the 6S movement. Thank you in advance.
 

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What a brilliant post, really interesting to see the process and to hear your observations.
I've always admired the Credor Seikos.
Nice work Noah.
It's really amazing the work that Seiko do - with the adaption of 7S to 4R35/6R15/20 and NE78/NE88 plus the 8R/6R/8L variations on a theme - mind boggling!.
 

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Thanks for reading and the nice comments, guys!

That special tool for open the rotor, do you mind explain how you build it?
Indera,
Here are the basic steps I took for making the tool. I made it to fit a standard watchmaker's screwdriver body.

1) turn down, cut to length, then round and polish the tips of three steel posts
2) turn down a brass rod to fit the screw-driver body on one end, and on the other to match the outer diameter of the raised portion inside the weight bolt
3) drill three holes the correct distance from center on the business end of the brass rod, equally spaced at 120 deg intervals. I used a milling machine and rotary table for this step.
4) turn down to correct dimensions a sleeve which fits around the raised portion of the bolt, and offers stability to the tool. This decreases the risk of slipping out as the sleeve helps keep the tool perpendicular to the bolt. The length of the sleeve in relation to the three posts is critical so that the bottom lip of the sleeve doesn't actually touch the bolt, which could mar it. The tool is designed such that the only parts contacting the bolt are the three tips, inside their holes in the bolt. Otherwise the mirror-finish of the bolt would be marred.
5) realizing that this isn't a tool I'm going to be using that often (can't afford to buy too many of these watches!), JBweld the pins and sleeve in place on the brass body. There are more elegant/less expedient ways you could accomplish this last step.

My oscillating weight bolt was on there tight, as it should be. I don't think I could have gotten it off without marking it up otherwise- it would only take one slip or one ill-fitting part of a tool under force to bodge it up. This is a shot of the body separated from the sleeve:

 

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Rilynp-
Thanks for sharing your informed observations on this Credor Seiko Mechanical marvel. The quote "What hath God wrought." seems to creep into my head but this is a mechanical time keeping precision device 'wrought' by the hands of skilled watchmaker men-team Seiko. Nice Job team Seiko. I used to wish that I could afford such a high quality device as a Credor but I have had my Seiko 6139 Pogue and other Seiko and Omega and Citizen and Bulova and Longines,Zodiac,Benrus and Casio timepieces that have served me well. And I will pass them on to my family after I check out of the 'Hotel of Life'. I am thankful for my Seiko timepieces to mark many of my 70 years of minutes,and hours and days moving about this earth. It used to frighten me that I would have to leave all my timepieces behind after My 'check out time'.
Then it came to me that after passing from 'Here to Eternity' there will be 'Eternal time' there -wherever 'there' is. And if they need to measure time I imagine they will use some kind of hour glass sand drop timer calibrated in eternal time or some such equivalent,since all of these are my musings of my imperfect imagination.
Meanwhile back on earth,where we lucky people have these Precision Time measuring devices, thanks again for explaining this Credor mechanical timepiece marvel.

Eli ForSeiko-Wondering how I change the date on my imaginary 'eternal time' hour glass.
 

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Indera,
Here are the basic steps I took for making the tool. I made it to fit a standard watchmaker's screwdriver body.

1) turn down, cut to length, then round and polish the tips of three steel posts
2) turn down a brass rod to fit the screw-driver body on one end, and on the other to match the outer diameter of the raised portion inside the weight bolt
3) drill three holes the correct distance from center on the business end of the brass rod, equally spaced at 120 deg intervals. I used a milling machine and rotary table for this step.
4) turn down to correct dimensions a sleeve which fits around the raised portion of the bolt, and offers stability to the tool. This decreases the risk of slipping out as the sleeve helps keep the tool perpendicular to the bolt. The length of the sleeve in relation to the three posts is critical so that the bottom lip of the sleeve doesn't actually touch the bolt, which could mar it. The tool is designed such that the only parts contacting the bolt are the three tips, inside their holes in the bolt. Otherwise the mirror-finish of the bolt would be marred.
5) realizing that this isn't a tool I'm going to be using that often (can't afford to buy too many of these watches!), JBweld the pins and sleeve in place on the brass body. There are more elegant/less expedient ways you could accomplish this last step.

My oscillating weight bolt was on there tight, as it should be. I don't think I could have gotten it off without marking it up otherwise- it would only take one slip or one ill-fitting part of a tool under force to bodge it up. This is a shot of the body separated from the sleeve:
Thank you very much for the tips, Noah. Will be my reference when I commission one.

One more thing: Did you move the lever on the regulator arm (pic below, in red circled, I don't know what the name is) before you regulate or made adjustment? AFAIK, and I may be wrong, the lever is to lightly clamp part of the hair spring. Do we need to release the clamp before we regulate? Thank you in advance for your time.

 

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Interesting and very informative! Thanks!

... from my phone, with the spell check from hell.
 

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My respect for you Noah is immense. Just the way you made the tool is mind-blowing. Then the way you took the time to photograph each step along the way and type up the narrative shows a unique ability to teach and share.

Thank you, possibly the best watchmaking thread I have ever read.
 

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You all are a warm bunch, thanks for the positive feedback. By the way, a nice companion piece to this can be found here, at Randall Benson's website (aka toomanywatches/Dr. Seiko): http://seikoholics.yuku.com/topic/863 (posted with permission, rights reserved). There are some excellent shots of the inside of an 8L35 movement, which is the undecorated/unadjusted version of the 9S55 Grand Seiko movement. I strongly recommend viewing the photos there to get a better sense of the basis of my argument for kinship between the 6S and 9S/8L streams- I wouldn't have been able to see the connection without Randall's photos and "going before" with the 8L35.

One more thing: Did you move the lever on the regulator arm (pic below, in red circled, I don't know what the name is) before you regulate or made adjustment? AFAIK, and I may be wrong, the lever is to lightly clamp part of the hair spring. Do we need to release the clamp before we regulate? Thank you in advance for your time.
Indera, feel free to ask away, there's a limited window of opportunity before I start to forget what I saw along the way! The lever on top of the regulator arm is eccentrically attached to the inside regulator pin. This design is also found in the 5216/4S series. Turning it one way or the other will increase or decrease the gap between the pins by moving the inside pin farther from or closer to the outside pin, which is sometimes necessary to fine-tune the isochronal characteristics of the movement, particularly between different states of wind (as amplitude changes).

It is a method to optimize the rate between several positions and states of wind, but does not have to be opened to remove the balance assembly from the balance bridge, as long as it wasn't pinching the hairspring to begin with. The rule of thumb is to have as small a gap between the pins and spring as possible and still see equal space on both sides of the hairspring, but in practice I've found that there is a margin for what "small" means, and can depend on other factors in how the hairspring is adjusted. So it is sometimes a "push and see"-affair, where you change the gap, take readings in several positions and in at least two states of wind, and see if that improved your errors overall or made them worse.
I chose to leave the pin relationship alone, just to see how well it was adjusted before. Good call in this case, as the change in average rate over 5 positions from full wind and after 24 hours running was less than a second (7.0 seconds/day average at full wind, and 6.1 seconds/day average rate after 24 hours running)! The difference between the fastest position and slowest position among the 10 readings (5 at full, 5 at 24H) was 7.6 seconds. I can say with confidence that these numbers are more impressive than they seem, often times certified chronometers do not achieve these types of results, nor are required to. I can't take any credit for this, beyond generally not making anything worse during servicing- the adjustments previously done were optimal to begin with. Call me lazy, but it's those types that are my favorite to work on :)

Rilynp-
Thanks for sharing your informed observations on this Credor Seiko Mechanical marvel. The quote "What hath God wrought." seems to creep into my head
Eli, good to hear your thoughts- we can go deep :) Is the quote you are thinking of this one, "What therefore God hath joined together, let not man put asunder", or one with a different connotation? In any case, I did my best not to put asunder without later.. re-sundering, I suppose. ;-)
I admire your acceptance of the ultimate finality, and while I don't yet possess that peace (still young enough to be in denial about it), I do find it a desirable goal. I'm glad you've found it.
 

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Great photos, really mouth watering.

Me: "WRUW while drinking?"
Quotron: "If I do it right.... nothing."

Me and my watches on IG: eyy_ron
 

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Rilynp-

One of my many younger brother's Rob, is a quality control engineer and the complexity of this Seiko Credor that you exposed and dissected and corrected is definitely way beyond his pay-grade and competence,and mine.Since a real man knows his limitations-I admit my admiration for your expertise. But my admiration for the Seiko Credor mechanical line grows.

The phrase,"What has God wrought?"-was Samuel Morse's first Telegraphic message sent in morse code.<" The first public message "What hath God wrought" was sent on May 24, 1844, by Morse in Washington to Alfred Vail at the Baltimore and Ohio Railroad (B&O) "outer depot" (now the B&O Railroad Museum) in Baltimore. The message is a Bible verse from Numbers 23:23, chosen for Morse by Annie Ellsworth, daughter of the Governor of Connecticut. The original paper tape received by Vail in Baltimore is on display in the Library of Congress in Washington, D.C."-from Wikipedia.org>

-The TransAtlantic Telegraph cables joined the continents of Europe and North America together in 1858.

The telegraph was the historical forerunner of the technological revolution to come in Communication and Transport in the 19th Century,that was followed later by the invention of the telephone(1876) and the automobile in 1886.The single wire telegraph put the American 'pony express' out of business in October,1861 just 6 months after the American Civil War was begun. And the use of telegraph and the Railroad became immensely important in the Civil War.

And the Telegraph & Railroad in 1869 joined the American continent coast to coast.The Telegraph poles ran along side wherever Railroad Train tracks were laid in America. The Railroads in America quickly connected farmers of California to the markets of the Midwest and New York and the East Coast. Texas and Western beef was shipped to the East on the Railroads and these trade connections became the routes of American Continent wide development.

And that desire and need for speedier communications and movement of goods and people became the joining of Instant communications by the Telegraph and rapid transport by Railroad Train=thus reducing Time and increasing the Speed of Transit and necessitated the need of Accurate Railroad time keeping to prevent Train collisions on the limited available tracks and lines of tracks.

-Thus we have the Need for = the Railroad Certified chronometer -<http://en.wikipedia.org/wiki/Railroad_chronometer> Railroad chronometers, or Railroad Standard Watches, are specialized timepieces that once were crucial for safe and correct operation of trains in many countries. A system called Timetable and Train Order, which relied on highly accurate timekeeping, was used to ensure that two trains could not be on the same stretch of track at the same time.And the need for Time Zones.

<"One notable watch inspector was Webb C. Ball. His first job as a time inspector was when he was brought in by the Lake Shore and Michigan Southern Railways in 1891 after a crash and was tasked with bringing their time inspection standards up to industry normals. Ball's career eventually led to him being the time inspector on more than half the United States' railways, leading to a far more uniform set of standards in the U.S.">
As a boy in the 1950's riding the train I remember the Railroad conductors with their pocket watches on a chain as they yelled."All Aboard!"-

Then, on October 4,1957 came Sputnik and the Space Race was on and extreme Accuracy required more specialized time keeping and along came the Bulova Accutron.And the Railroads were surpassed by Trucks on the Highways and a New Space Age era arrived and we are in it still.

In the 1960's the Bulova Accutron wrist watch was described as the most accurate watch on earth and in Space.And I still wish I had bought one as they were just so technologically marvelous and electronic.<http://www.accutron214.com/AccutronHistory.htm><http://www.accutron214.com/AccutronGallery/Pages/AdGallery.htm>

And while American astronauts wore Omega Seamaster mechanical chronographs on their wrists on their Space voyages-all or most of their Space Vehicle instruments were Bulova Accutron devices.

Then in 1969 the first quartz wrist watch came from Japan & Seiko.<First quartz wristwatch movement Caliber 35A, Nr. 00234, Seiko, Japan, 1969 (German Clock Museum, Inv. 2010-006)> And nothing has been the same since in timekeeping and the watchmaking world.And I bought a Seiko 6139 Pogue chrono in 1971 because I loved the Seiko chronometer and I could not afford the Seiko quartz watch.

Now, in 2014 we have smart phones that can access Wikipedia and many University libraries on all the continents of this world if you have cell phone tower connectivity or WI-Fi or a satellite phone. I keep in daily touch with my mates in Alaska and Oz and in South America and California and do it as casually as visiting thewatchsite.com for my daily visit. And all the continents are joined by these instantaneous communication smart phones and computers and Skype and Google and E-mails and tweets on twitter and I am almost overwhelmed by the speed and demands of these marvels.

So here we are in 2014 with extremely accurate Quartz and mechanical timepieces and cell phones and satellite phones and GPS and atomic timekeeping signals around the world.So for Now,We have pretty much solved our accurate timekeeping Needs. But there are other issues that need our Worlds attention.

We also have Pandemics and War and World Economic depression and Earth Warming and Energy problems and many other problems that need addressing and dealing with and solving. Lets hope we can get our act together and find some answers to our World wide pressing issues, In the Time that we have left.

Eli---Be Well Amigos-
(Yes,I too am a seikoholic though Not recovering)
Another favorite quote of mine is = " O Brave New World that has such creatures in it."-from Shakespeare -The Tempest- spoken by Miranda as she sees her first young man...!
It also is the title of 'Brave New World'- a novel written in 1931 by Aldous Huxley and published in 1932. Set in London of AD 2540 (632 A.F.—"After Ford"—in the book), the novel anticipates developments in reproductive technology, sleep-learning, psychological manipulation, and classical conditioning that combine profoundly to change society.It is a very good read.
 

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Thanks for the fantastic post Noah. The dedication to built your own tools and steps to ensure they did not cause any damage is very impressive.

Do you still have the dimensions of the tool on hand. It might be handy to list these somewhere so someone else can build a tool and not have to reinvent the wheel.

Thanks again for sharing this great breakdown.
 
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