Reply With QuoteAlways a brilliant read Martin.
I've not linked to any of my blog posts recently here but thought some of you might be interested in my latest adventure grappling with a 62 year old Girard-Perregaux Gyromatic.
This watch is interesting for all sorts of reasons, not least of which its use of a square Brevet compression case
and the fact that the 22 jewels serving the automatic winding mechanism
comfortably outnumber the functional 17 jewels tasked with aiding the operation of the base Peseux hand-wind movement.
Anyway, if you fancy learning more about these fascinating watches, feel free to take a peek here:
https://adventuresinamateurwatchfettling.com/2021/05/19/girard-perregaux-gyromatic-39-jewels-from-1959/
Martin
Always a brilliant read Martin.
Cheers,
Ben
..... for I have become the Jedi of flippers
" an extravagance is anything you buy that is of no earthly use to your wife "
Really enjoyed following that meticulous restoration. Lovely watch that was definitely worthy of such TLC.
I enjoyed that, thanks for posting. My Dad had a GP Gyromatic for "best" and I think that is where my love of watches came from, being allowed to change the day and date when he wanted to wear it was a little treat.
Thoroughly enjoyed that.
Cheers,
Neil.
Excellent write-up, I lack the patience and photographic skills to produce anything like this and I admire those who can. I’m impressed by the tenacity in sourcing the replacement crystal, for me that would be the biggest challenge of the whole job! The watch looks superb and its a credit to you.
A couple of pieces of advice: you referred to using 8217 grease on the barrel walls, I recommend using Kluber p125 instead in all automatic applications. It’s expensive but in my experience its the best to use, particularly if the barrel walls are worn and you’re trying to prevent the mainspring slipping prematurely. I used to use 8217 but Kluber p125 is better, particularly with barrels that have scalloped walls (omega 550!)
When taking any automatic watch apart I always take the auto- winding mechanism off first. It’s easier to clamp and handle the movement without the rotor in place and it also allows the condition of the movement to be assessed easier prior to stripdown. That’s a mistake I used to make when I started, I would tear the movement to pieces quickly and crack on with cleaning, sometimes encountering problems during reassembly that could’ve been resolved easier prior to cleaning. You can learn a lot from the movement prior to stripdown but once its been reduced to a pile of parts it can’t tell you anything!
Always be on the lookout for jewels/ bearings that can’t be accessed for lubrication after reassembly, I’ve done exactly what you did myself and had to remove the minute wheel again to get access for oiling. I always like to build the keyless work and minute wheel up first and I’ve learned to spot inaccessible oiling points and oil them first.
You don’t mention epilame treatment in the write- up. I treat the escape wheel, pallet fork and balance pivot end jewels with fixadrop and I recommend always doing this. At around £100 for a small bottle it isn’t cheap but it does prevent migration of the lubricant.
Finally here’s a tip for avoiding the loss of small shepherds crook springs; place the movement in a polythene bag when removing and refitting them. Its a bit more fiddly but it prevents them making a bid for freedom and being lost forever.
I was impressed with the amplitude and your choice of mainspring, maybe you got lucky! The strength of the spring is proportional to thickness to the power of 3 (cubed), so a slightly thicker spring can increase strength by 15-20%. On an old movement the amplitude is unlikely to be excessive but it can happen, if so a good trick is to increase tension on the centre seconds pinion spring ( if it has one) to bring it down a little.
Keep sharing the write- ups!
Great wite-up, very interesting. As you say, the case is very interesting too - I wonder how many other caseback solutions have died off over the years.
Captivating read on your blog site, thank you for sharing!
Great write up. Not seen a case fitted like that- going to file that for a future project.
Dave
Thanks very much everyone. I try to deliver a warts and all account in these write-ups - including mis-steps and mistakes where they happen. And they happen to everyone. I've seen enough completely butchered movements at the hands of professional watchmakers to know the truth if that statement.
As to barrel lubrication, I have experimented with all sorts of approaches but not yet bitten the bullet with Kluber, put off by the outrageous cost. The proof of the pudding though in terms of performance is in the eating and 280 degrees of amplitude works for me in a 60 old watch.
Martin
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Agreed, Kluber 125 is outrageously expensive (around £80 for 5grams, but 5g would last a lifetime) and in many cases it isn`t necessary to get a good result. If you don`t fix many watches it's hard to justify the cost, that's the dilemma.Originally Posted by MartinCRC
A good trick for checking whether there's a problem with the barrel wall/braking grease effect is to fully wind the watch, place it on the timegrapher dial down with the back off, then slowly turn the rotor with a piece of Rodico and watch the amplitude reach a peak. if the amplitude falls significantly over a minute then settles at a lower level it's a good indication that the spring is sliding excessively around the barrel wall. Typically, amplitude will reach 275° than fall rapidly to around 240 if there's a problem. On some barrels with a cutout it's possible to observe the spring sliding, it literally creeps around the wall and keeps sliding for around 20 secs until a significant amount of tension has been released. Ideally the spring should only slide a small distance and that's where the braking grease can make a difference. The fluted/scollaped barrels used on some watches can be a problem when they wear , the design is supposed to allow the spring to move in a set increment then stop, but once the peaks of the indentations wear this doesn`t happen and they perform worse than a smooth-walled one. ETA barrels are similar, they have small indentations that can become worn, in these cases the Kluber 125 makes a big difference although ideally a new barrel is the answer.
The measured amplitude on this watch was recorded an hour or so after a full wind and so any slippage would have occured already. The barrel wall is smooth on this movement and the vast majority of watches that I work on are vintage Seiko, all of which employ smooth walled barrels. I may yet experiment with Kluber but I have a feeling that it may not turn out to be especially useful with my sort of projects. But I am curious and always keen to experiment. I just need to overcome a little of my acquired North Yorkshire parsimony!
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Very enjoyable - many thanks.
Regarding the unusual case design, Omega did the same with some early 70s Constellations, I’ve worked on a few and I own a nice bimetal one. Its fine provided the seal around the base of the crystal (which is under compression) doesn’t degrade, they do tend to harden with age and start letting water in. The grub screws also corrode and can be difficult to remove, especially if the heads are damaged.
Considering the novel case design and self- winding this is an unusual and interesting watch, I’ve enjoyed the post and it’s rekindled my interest in watches and repair work.
Watchwork can be daunting and somewhat frustrating but there’s nothing like the satisfaction of wearing and enjoying a watch that you yourself have sorted out, far more rewarding than spending a few grand on a new watch after grovelling to the AD to be allowed that privilege.
Nice write up Martin and top detective work on the crystal!
Thank you! In my crystal research, I was bumped onto the right path by Richie Askham of this parish and then only had to identify the right part number and find stock.
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Thanks for that:) very interesting read
Thanks for posting that - I enjoyed all of it. I have a Croton Nivada Aquamatic project that has an almost identical case - reading this thread has reminded me that I need to take some better pictures of it.
Talking about the crystal - is there something I missed? Was giving the original a polish and re-fitting it not an option - couldn't see a complete crack from your photos? I think I'm going to have a similar odyssey looking for a replacement for mine which is most definitely cracked.
In the Sotadic Zone, apparently.
Re: the crystal, it was badly scratched across its top, had worn corners and sides, was discolouring and also had a crack close to one of the corners. No amount of polishing was going to get it looking anything other than an over-polished and well past its end date acrylic crystal. And I am just in the habit of replacing old acrylics where I can. The crystal is the window to the dial and I'd just rather it is as good as possible.
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Thanks for the extra info re the crystal. I took some photos of my Croton Nivada with a similar case. The feature of this watch that really leapt out were the chamfered lugs - I have plans to get hold of a Nivada Antarctic at some point, which has very special chamfered lugs, and thought this would make the perfect pair. Having proved that I really like the style I suspect that developing this project will involve getting hold of at least one complete donor with a decent dial.
This has what I would call a smoker's dial.
And I have no option but to try to find a new crystal - preferably brand new like yours but even from a donor would do.
Interestingly there is a G-P with a very similar, thought not exactly the same, case on Ebay at the moment - I must see if I can find the link.
In the Sotadic Zone, apparently.
That dial is gorgeous - I wouldn't be so quick to replace it. There are a couple of Croton crystals listed in the online G-S crystals catalogue. If you can measure yours, you could identify a potential replacement.
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Last edited by MartinCRC; 25th May 2021 at 20:03.
Thank you for a very informative and enjoyable read. The watch is also gorgeous.
Thanks - I don't believe in redials so that one won't be going anywhere - I'd just like to find an identical one in better condition. I've been know to nurse projects for years so I have plenty of patience. I found the link to the other GP and the case screws are in a slightly different position - between the lugs rather than behind them:
https://www.ebay.co.uk/itm/164768631784
If they were asking anywhere near a sensible price I might be interested (but then I suppose I should finish the Croton project first).
I'd put money on all 3 cases coming out of same case maker.
In the Sotadic Zone, apparently.
Are they not Brevet cases?
Isn’t that just French for patent-protected?
In the Sotadic Zone, apparently.
You have just revealed the extent of my ignorance! Apparently the Brevet 189190 was a 1936 patented invention of Schmitz Frères & Co and then first used in cases made by Gallet but after 1951, a whole bunch of different makers made clamshell cases.
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I'm going to write the crystal dimensions here because I've already taken them once and mislaid them
width/height including lip 24.6mm x 24.6mm
width/height of the visible crystal 21.8mm x 21.8mm
I'm in the process of looking through the G&S catalogue now and I think it's a CMS 519.
Last edited by Carlton-Browne; 30th May 2021 at 09:12.
In the Sotadic Zone, apparently.
Fantastic read, thank you.
Martin that was an enthralling read, well documented and well written. That is a stunning overhaul and a gorgeous looking time piece. The advertising blurb to go with it is fantastic. Worthy of saying 39 jewels. Especially in those times. Maybe there is something to low beat watches after all.
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A very interesting post and an enjoyable read . Thank you for posting .
Thank you. I think on balance that the justification for trumpeting the 39 jewels deserves the benefit of the doubt, not least because none of them are purely decorative - they all have a function.
Martin
Thus reducing wear and friction I guess?
It’s a restoration to be proud of that’s for sure!
Well done again
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