This entry revolves around the appearance of an obstruction that turns out to be nothing of the sort but rather emerges as an exemplar of the jeopardy that exists in taking too literally an instruction not to do something. You’ll see where we are going with this as we work our way through this cautionary tale.
Those of you whose consumption of goggle box output has shifted away from big budget broadcast to small budget homespun (i.e. consumers of YouTube), will know already that the breaking of my three month long mini-sabbatical has been marked by the focusing of my attention towards a rather fetching cross-hair dial Grand Seiko 6146-8000 from April 1969.
This watch is a member of the 61GS series of automatic, high-beat Grand Seikos that were produced from 1967 to about 1974.
The 61GS was the second generation of Grand Seiko automatic, following on from the rather short-lived 62GS that reigned from 1966/7 to 1968 (the 62GS was preceded by the Seikomatic 62 Chronometers in 1966 that were identical in all but branding).
The high-beat credentials of the 61GS are entirely authentic in that these movements run at 36000 beats per hour or, to put it another way, 10 beats per second or 5 Hz. We’ve discussed some of the history of the high beat movement in another post recently and I don’t propose to revisit that here. Suffice to say that in running at such a frenetic pace, high-beat movements are less susceptible to external perturbation and can recover from such more quickly. There are no other fundamental reasons why a high-beat movement should be more accurate than low beat. The down side to a high-beat operation is essentially two-fold: firstly the gear train is under greater stress and relies on modern synthetic lubricants to protect against wear and, in spite of this, also tend to require more regular servicing; secondly, to drive a high-beat gear train requires a power source of greater potency and that means a stronger, thicker mainspring. Thicker mainsprings occupy more real estate in the barrel and so provide a shorter power reserve than thinner, longer mainsprings. And in an automatic watch, a thick mainspring needs a heavier winding weight which itself then needs more space. That sounds like a lot of downsides, but let’s consider the upsides by meeting our subject.
Phwoah! Even in this slightly dilapidated state, this is one striking object of desire, especially viewed from the front. To the rear, the story is not quite so rosy in that the gold medallion is conspicuous by its absence. With that flaw set to one side for the moment, this is a very presentable watch indeed with the external signs of use suggesting simply that this is a watch that has been worn but not abused. We shall come back to the issue of the missing medallion later on. Let’s crack open the lid, and take a look at the power train:
The external impression of use, not abuse carries forward to the interior. The movement looks clean, free from corrosion or pitting and largely free from friction wear to the plates from the rotation of the automatic winding weight. Dropping the movement out provides an unobscured view of the dial and handset.
The dial is immaculate, the minute and seconds hands very clean and tidy but the hour hand displaying signs of some tussles with previous watchmakers. The rear of the dial displays the date code 9.4 indicating that it was produced in April 1969, the same month as the case.
The calendar day wheel is mono-lingual which is consistent with the specification of all day/date watches released by Seiko up to this point with the exception of the Daini-produced Seikomatic-P 5106. Bilingual day wheels would not arrive in Suwa division watches until the introduction of the C-variant of the 6106 in about 1969.
Let’s take a look at the balance side of our 6146A, minus its winding weight.
A bit grubby, yes, that’s to be expected, but otherwise very few signs of wear and tear. The underside of the autowinder mechanism shows a fair amount of grime but we note that the jeweled bearing at the centre of the pawl lever is protected by a small plate. A nice touch in this upper echelon version of the 61 series calibre.
We’ve seen all of this before but not for a little while so let’s pause to note the jeweling of the mainspring barrel hole in the train wheel bridge as we progress further with the deconstruction of the movement.
Let me draw your attention to the word OPEN, printed on the lid of the barrel. The true purpose of this apparent instruction to do just that is revealed when we remove the bridge.
Not OPEN, but DO NOT OPEN. In capitals no less. We’d better do as we are told. Or perhaps not. We’ll come back to this shortly. Before we do, let’s pause to note the presence of the reciprocal jeweled barrel bearing in the main plate, partnering that in the train wheel bridge.
A bird’s eye view of the stripped calendar side, with keyless works still in position reveals how refreshingly free this movement is of hyperbolic additions of redundant jewels. This is a 25 jewel movement where the choice of what to jewel and what not to jewel appears to have been made by the movement’s designers and not the marketing department. It is worth noting the enclosed jeweled bearing that serves the pallet fork and the Diafix setting that serves the escape wheel.
A close-up of the setting parts reveals the presence of a (rather gummed up) winding pinion, there to provide the hand-winding capability by transmitting rotational action from the crown to the captured crown wheel mounted on the train wheel bridge and from there to the ratchet wheel mounted atop the barrel arbor.
Let’s get back to that Do Not Pass Go instruction and consider what exactly this means. The received wisdom has, for some time, been that high-beat 61-series barrels are sealed and unserviceable. Whether it was Seiko’s intention that the barrel should provide lifelong service or simply that they were to be replaced lock, stock and, err, well (ahem) barrel at service is unclear. Nevertheless, with stocks of spare part replacements now all but exhausted, some route to dealing with this particular problem needed conceiving. In previous posts (here and here) where I’ve had to confront this issue, I had taken the approach of fitting Generale Ressorts mainsprings of appropriate specification to spare 61-series barrels, and stashing the original 61GS barrels in my parts repositories. This strategy was prompted initially by the assumption that a sealed barrel means a sealed barrel and that the instruction not to open actually meant opening is not an option. However, in tackling my first 6145 a few years back, I did in fact crack open the barrel to confirm my suspicion that the mainspring was broken (it was). Having done so (and in spite of the ease with which that operation was accomplished), I then presumed that some clever watchmaker black magic involving methods beyond my skill-set would be required to re-seal and so left that barrel disassembled and resting in perpetuity.
This brings us to a consideration of this latest 6146 barrel, eyeing me with its arbor, daring me to disobey the instruction printed on its lid.
In rising to the challenge, I discover once again, that removing the lid from a 6146 barrel is no more arduous or challenging than removing the lid from any other barrel. I would note in doing so however that the lid of a 6145/6 barrel is on the opposite side compared to all of the low-beat 61-series variants (6105, 6106, 6119, 6138, 6139 etc).
The mainspring is caked in S-2 grease, great clumps left behind on the barrel floor following extraction of the spring. The mainspring is noticeably thicker and obviously shorter than those in the low-beat watches.
As all climbers know, the summit is only half-way to the final destination and so we pause at this point knowing that it is all very well having successfully extracted the mainspring from this ‘sealed’ unit; we still need to refit it and close up the barrel. Given that the parts are at this point percolating nicely in the watch cleaning machine, we’ll find ourselves confronting that challenge (such as it is) very shortly.
The fact that the lid of a 61GS barrel is located where the floor is located in all other 61 series barrels means that the mainspring has to be wound in left-handed rather than right. In the absence of a left-handed mainspring winder, I tackle this task by first seating the mainspring onto the shaft of the mainspring winder handle with the coils following a clockwise path as viewed from the top of the shaft.
With it mounted in such a fashion, fitting it to the winder drum requires it to be wound in backwards, something that can only be realised if the nub on the handle’s shaft stands sufficiently proud to gain purchase on the slot at the end of the mainspring. Fortunately, it does and I successfully manage to install the mainspring into the winder’s drum.
The strength of the grip of the spring on the handle means that extracting the shaft required rather more gentle teasing than normal. The realisation of that process is evidenced by the satisfying sight of our mainspring safely installed in the drum.
Fitting the cleaned mainspring into the barrel is now just a matter of routine: start by lubricating the barrel floor and walls with some molybdenum grease.
Locate the winder drum into the barrel and press the plunger home. The mainspring transfers with a satisfying click as it relaxes into the slightly more accommodating space offered by the barrel.
The final step requires not only the completion of a physical procedure but also requires that we overcome the psychological hurdle presented by that original DO NOT OPEN instruction. Surely, refitting the lid must require a technique rather more advanced than simply pressing it home? It turns out that it doesn’t.* Fitting the lid is no more challenging than fitting any other barrel lid and the result betrays in no sense at all that we have been left with anything other than a barrel returned precisely to its original state, with no violation having been inflicted upon the integrity of the interface.
With that step complete, we can move on unruffled to the reconstruction of the movement. I’ve worked on and documented the servicing of enough 61 series movements in the past to hop and skip through this part of the process but let’s pause to observe the installation of the barrel back into position betwixt main plate and train wheel bridge.
We note in passing the presence of the seconds stop lever, there to provide a seconds hacking facility. The process proceeded smoothly from this point and with both Diashock settings installed, the pallet jewels oiled and some power wound into our freshly cleaned mainspring, the movement leaps into action.
A quick demagnitisation and a very minor tweak to the beat error and the movement is humming along at its prescribed 36000 bph, timing trace entirely free from noise and the balance swinging back and forth through an arc of nearly 250 degrees.
I’ll perform a more thorough regulation later but for the moment I am more than satisfied. I think we are ready to fit the reassembled autowinder before completing the dial side.
The calendar parts all come together easily and all function correctly, natural changeover as well as the date quickset function.
The dial ring and dial are fitted next, the latter having benefited from a light clean to remove a few bits of debris and some faint tarnishing from some of the markers.
When it came to refitting the hands, I noticed that the hour hand was quite badly scored, probably the result of some clumsy attempts to clean it as part of a previous service. The lovely condition of the dial deserves better but there was no immediately obvious replacement to be had from any of the usual parts suppliers. But then I remembered that I’d acquired a Lord Matic as part of a job lot that I vaguely recalled having a similar handset.
My memory had not defeated me and indeed, the hands were of exactly the same style as those fitted to the GS. The small case size of the LM also meant that the length of both hour and minute hand were identical too. The only slight deviation was that the LM minute hand tapered to a broader tip than the GS original but the hour hand was perfect. I was only interested in the latter anyway and so our LM makes the sacrifice but can take some satisfaction in knowing that it has donated a body part to a brother in need.
When I bought this watch, I did so realising that although it felt like I had bagged a bit of a bargain at the time, there was a clear reason why I’d got it for a good price: the caseback medallion was missing, a flaw that has a disproportionate effect on the value of these watches. This is curious, especially because when you wear the watch, the caseback sits face down on your wrist out of sight. However, it cannot be denied that the absence of the medallion is not inconspicuous and it is understandable that the most sought after examples will be those still in possession of the little disk of gold.
My original plan, having bought the watch, was to fit a display caseback and not sweat the absence of the medallion but I also entertained a hope that I might stumble upon a solitary complete case or just caseback with the medallion in place. As the market continued its inexorable rise in the period since buying this example, so my hopes of acquiring an economically viable donor receded. However, I have a sense that the combined effect of spectacular political buffoonery on both sides of the pond is starting to erode confidence in the speculators who have fed this bubble and detect just the first hints that we are on the cusp of a correction (I use that word knowing that ‘correction’ can mean anything from a mild softening in the market to a complete bursting of the bubble). As evidence of that, earlier this year, I managed to lay my hands on a 6146-8000 case and caseback, complete with original medallion, in crisp overall condition and at a price that I felt comfortable with. Now that the movement is ready to be installed back into its midcase, I need to confront the question of whether I should substitute the original case wholesale with the donor or just exchange the casebacks.
Where the original case is nicely eroded at its edges as a result of the gentle passage of time, it is still noticeable softer all round than the much sharper donor. There is also the question of temporal consistency to consider. The original watch dates from April 1969; the donor from September 1968. While this is only 7 months, I worried a little that I would be transplanting a cross-hair dialed 6146-8000 into a case whose production date preceded the introduction of this model variant. A quick survey of images online suggests that March ’69 may be as early as they come but the cross-hair variant first appeared in the No.1 edition of the 1969 JDM catalogue and I know from the dates of these catalogues relative to actual production dates that watches are produced for months prior to their appearance in the catalogues (as evidence of that, the earliest 6146-8000’s date from October 1967 but they don’t appear in JDM catalogues until the second edition of the 1968 catalogue). It would appear that I’ve talked down my own developing discomfort at potentially opening a rift in the space time continuum and I decide that it’s actually ok to substitute the nicely softened original case with the sharper but older donor.
See, it’s sharp. Yes, the crevices are a bit grim but they always are with old watches. A round of pegwood-assisted grime removal, a dose of ultrasonication and some tooth-brushery and we have a spic and span case ready to partner with our movement. I encounter a bit of a glitch, however. In removing last traces of fluff from the crown tube area with some Rodico putty, I manage inadvertently to extract the crown tube from the case.
This is somewhat ironic because one of the reasons I bought this case in the first place was to initiate some trickle-down musical chairs in which the old case could be used in another 61GS project whose case had lost its crown tube. There is nothing for it but to investigate options for affecting a repair. Some research followed that suggested that a suitably chosen Loctite adhesive compound would provide more than sufficient security to provide a lasting and watertight fix. After perusing the Loctite website, I settled upon Loctite 638 retaining compound, designed for just this purpose.
A coating applied to the inner surface of the crown tube hole in the case and another light coat around the outside of the mating surface of the tube and we are ready to reunite the two parts.
I inserted the tube into the hole, making sure the cut-out was oriented towards the case back and then left the compound to dry for a day or so before moving on.
We are still a few steps away from completing this little marathon but I think I can see the light at the end of the tunnel.
What you may not have appreciated previously is that the replacement case was missing its bezel. I was unconcerned at this because my foraging instincts had already unearthed a new old stock replacement a couple of years ago. Before we can fit the movement to the case, we need not only to fit that new bezel but also a new crystal. I have a few Sternkreuz replacements for the 310T08ANS and select one of these in the absence of an easily sourced Seiko original. As is common in my experience, the Sternkreuz crystal required a little adjustment to seat in the case aperture and moreover, the supplied tension ring proved to be incompatible with the dial (there was not enough relief around its underside to allow the dial to sit correctly with the result that the stem would not locate in the movement). I solved this problem by salvaging the tension ring from the original crystal which allowed both crystal and movement to seat securely and correctly.
The new bezel is fitted using a crystal press.
There remains one really quite fiddly job to complete. The crown used with this model is one of those designs featuring a captured gasket sitting behind a crimped-in washer. Such crowns are not designed to be serviced but my recent successes in extracting and refitting fresh gaskets to similar designs encourages me to have a go here too. Some determined effort with a pair of retired watch oilers and a sacrificial 0.6mm flat-bladed screwdriver blade resulted in the eventual removal of the hardened and entirely non-functional original gasket (in about a million pieces). Having thoroughly cleaned out the crown cavity, I select what I think looks like a prime gasket replacement from a choice of three candidates. With lashings of silicone grease and some very determined effort, I managed to cram the fresh gasket unharmed into the waiting space and we have once more a functional water resistant crown.
A test fit of the crown to crown tube suggest a snug fit, the gasket gripping the tube nicely. We are ready now to offer up the movement to the case.
We place the movement on a case cushion, eliminate traces of dust from the dial and case interior, lower the case onto the movement, invert, fit the winding weight, crown and stem and we are nearly there.
I select a fresh caseback gasket, lubricate it, fit to the caseback and close the case, its exterior now sporting a perfect Seiko GS gold medallion.
Turning over, we get our first sight of the complete watch.
The final task is to select a suitable strap. The 1969 catalogue entry shows the cross-hair dial variant fitted to a textured crocodile strap, with a small scale-structure and no side stitching.
Rather than attempting to duplicate that, I select instead a lizard strap whose small scale-structure duplicates to some extent the look of the original. With the new strap fitted to the watch, I think we have a bit of a hit.
Every now and again, the completion of a project produces an end result that can take the breath away.
That a 50 year old watch has the power to do that is a testament to the brilliance of the original design. In this variant, with its charismatic cross-hair dial and blocky hour markers standing proud of the dial, lending a beautifully three-dimensional quality, we have a genuine star in the mantle of Seiko output from this golden era.
* The surmounting of the curious psychological hurdle required to tip from obedience to disobedience was aided by some prompting from a reader who directed me to a recent YouTube video made by Spencer Klein. Faced with the same conundrum as myself in contemplating the issue of sealed barrels, Spencer notes in his video that the barrel lids simply press back into place. He’s been sending his barrels off for service for some time and you can sense the exasperation in his voice at this discovery.
Phenomenal work, my favourite grand Seiko.
You’re getting quite good at this….chuckle! 🙂
Jonatan Biloz said:
Oh I see! Yeah 30 hours seems a tad low to me as well. But well, I’ll leave it as it is for now! Thanks for taking the time to reply. Cheers!
Yet another extremely entertaining read. I would never have thought of using Loctite 638 for a crown tube, must give it a try. I have numerous tubes that have come free or loose.
Look foreward to the next one.
Paul Cornforth said:
Hello Martin ,
Another fabulous tale , and what a watch.
I’m struggling to conjure up a single adjective which does it justice , so I won’t bother and shall just look at those last three photographs once more.
Well done that man..
Thanks for that Paul. I’m glad that you enjoyed this one and yes, I agree with you: words don’t really do this watch justice!
Jonatan Biloz said:
This is awesome! I have a 6145-8000 that was recently serviced and currently runs at +5 to +7 secs a day… However the watchmaker didn’t service the barrel and main spring… As a result, I’m getting exactly 30 hours and 15 minutes from fully wound to stop working. How many hours are you getting out of this one? With the barrel and spring serviced?
Hi Jonathon, I’ve not actually measured the power reserve on any of my 61 series but 30 hours does seem a little low. By definition though a high beat uses a thicker and hence shorter mainspring and so for a given barrel size, you would reasonably expect the power reserve not to be as good as an equivalent low beat movement. Sorry not to be of more help.
I recently found your blog and really enjoy it, I started to read all of your post. Keep up the good work 🙂
Thanks Sly, I’m pleased to hear you are enjoying it!
Brilliant write up and jaw-dropping photos too! I thoroughly enjoyed this entry.
Thank you! I’m pleased to hear you enjoyed it.
Hendrik Lolinhandary said:
Hi Martin, thank you so much for this post. I managed to overhaul my first 6145 using this as guidance. Based on this, I also opened the mainspring barrel and cleaned the mainspring (luckily mine was not broken). I’m about to get a second 61GS and seems the mainspring is broken. I will try the 6139 set and see how it turns out. Looking forward to my next project.
No problem Hendrik! I am please to hear you found it helpful. Good luck with your next project.
All the best
Just got my hands on a lovely cross hair 6146 with broken mainspring. What a beauty !
Did you have any success with your 6145 ? Did original barrel + generale ressort replacement mainspring work for you or did you go for a 6139 barrel + generale ressort combination ? What power reserve do you get after ? I’m asking to give the good parts for my watchmaker to service the watch (6139 barrel is cheap, so is generale ressort mainspring)
Hendrik L. said:
Hi Olivier, sorry for the late reply. I seldom monitor the chat. Yes, my original 6145 barrel/arbour works well with GR2537X. At least I can tell that amplitude and other figures in timegrapher look OK in my case. I haven’t tested the power reserve though. Will do so some time in the future. Good luck with your project.
Hi Martin, many thanks for sharing your experiment. I enjoy your blog.