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Omega 1920's pocket watch 18SPB; Info & help please.


Endeavor

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Dear All;

Last night on a party a gold-plated Omega pocket was "thrown" into my lap; allegedly a none-runner. It has its sub-dial seconds-hand missing, chain seems to be the original.

Before going to bed around midnight, I wound the watch, it ticket and ran until this morning 07:00, after which it stopped. The balance makes a few ticks after shaking, but stops again. So, it's a "runner" ;) Clearly dirt in the movement, behind the glass, on the dial etc.

What else do I know / found out so far about this watch; On bidfun-db ( http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&&2ustu&1095006620) I found a similar looking watch, same movement, same case, different dial & hands, allegedly 1924 era and an enamel dial. The 18SPB movement seems (seemingly) pretty straight forwards and looking at case marks / movement-screws-heads; not very often "messed" with. The case numbers do match-up and the gold-plating ware on case & chain seem to match up as well. The sub-dial seconds-hand pivot seems still standing, so why the hand is missing ??

Before getting my screwdrivers and spanners out, I'm trying to get some information such as;

- Even though the movement seems pretty straight forwards, an exploded view and lubrication scheme; including types of oil used for these pocket watches?

- How do the hands come off (straight pull?) and special precaution taken with regards to an enamel dial?

- Where to order a new main-spring (if advisable?) and where to find sub-dial seconds-hand (eBay / CousinsUK / .......)? Any info about Pivot diameters ?

- Pulling / disassembling the crown / winding stem? A little screw seems to hold the winding stem, but unlike with a wrist-watch, this crown has the additional push button to open the front-cover.

- Any do's / don'ts / watch-out for's / tips & tricks ..... ?

My intention is to strip, clean & restore this heirloom watch, making pictures of the journey for a forum "walk-through".

Any help / info is highly appreciated ;)

Omega-1.jpg.095d319f19a8d77d38b28669667819a7.jpg

Omega-2.jpg.0a8cdbdb02feb9e6706795bcc547ac82.jpg

Omega-3.jpg.fcbbe08c57aed3471ed3605ca6e3d2bf.jpg

Omega-4.jpg.0138bfbca39a08d22a08900a8d8a12b2.jpg

Thanks; Roland.

 

Edited by Endeavor
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Progress :)

While waiting for some help, I couldn't help myself to start "poking-around" and lo and behold, it "fell apart" ;)

Omega-16.thumb.jpg.df3b3b507dcffccc82d909fa3d029ec6.jpg

Some parts no oil, some parts with dried out oil and some parts were swimming in it;

Omega-10.thumb.jpg.a2bcf22316a80030197e415e18dd23e8.jpg

The main-spring seems tired, any idea's where to get a new ? I've never ordered a new spring for a pocket watch of this age ... :huh: What measurements to take?

Omega-18.thumb.jpg.a87955378cbf14cc62a20283fafb4189.jpg

Also still stands which oils to be used for a pocket watch ....... about the same as for a wrist-watch ?

Hope to hear .....

 

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3 hours ago, Endeavor said:

The main-spring seems tired, any idea's where to get a new ? I've never ordered a new spring for a pocket watch of this age ... :huh: What measurements to take?

I've seen worse for pocket watch mainsprings but a new spring would be nice. You need the width and strength and  length. Then mainsprings are interesting in how their measured. Then mainsprings have interesting measurements they can be measured in metric, inches and Dennison or combination of all three. Which of course depends upon the watch like an American pocket watch is conceivably all three this being Swiss probably could be all metric but package could still be marked in Dennison. Then the end of the spring is important and your end is interesting. The barrel has a slot like a T end but it also looks like we need a better view of the end of the spring is probably a T brace type spring. Which is interesting because the 18 SPB doesn't have a spring like this.

So metric with of the spring. Thickness micrometer is better than a veneer caliper because you usually wiggle the spring around and you  usually get the wrong measurement. Then the length for anything I usually do is in inches but you can make it metric. Then I can look at my mainspring book see what's close it looks like it's probably a DBH end at least that's what the majority of Omega pocket watch spring ends are if they're not the standard  end. Then photograph of the end of the spring just to make sure we see what the end type is.

 

 

 

Mainspring ends 1.JPG

Mainspring - DennisonChart.pdf

Mainsprings ends 2.jpg

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@JohnR725:  Thank you for your help ;) . Reading your article; measuring a main-spring seems to be a science on its own ! :). Perhaps I may have found something in Italy ....... the seller claims it's a  "Ressort Muelle" aftermarket spring allegedly fitting the Omega 18SPB. If it doesn't, I will post some more pictures of the old spring and we go through the "motions" of trying to determine what I need to order .....

 

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Cousins has scans of the GR book and this section has the 18ligne Omegas https://www.cousinsuk.com/PDF/categories/7810_GR Pages 141 - 150.pdf, they also have the 18SPB spring in stock.

The 18SPB has a standard end spring like the one you have removed, but the barrel you show looks like it should have a DBH end spring. Other 18ligne Omegas do use DBH springs. Are you sure this is an 18SPB?

It’s not unlikely that the watch has the wrong spring fitted, so if you can’t be sure about the calibre, your best bet is to measure the barrel diameter and work from the calculator on this page http://www.vintagewatchstraps.com/mainsprings.php

With regard to oiling, see here http://www.nawcc-index.net/Articles/BTI-The_Practical_Lubrication_of_Clocks_and_Watches.pdf

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@StuartBaker104: I think you pointed out the first Gremlin ! Very well spotted indeed !! :thumbsu:

Sometimes one makes small observations which are stored somewhere in the back of your head. These observations are small and do not necessarily raise a red flag (for many different reasons; lack of experience is one of them). These observations are like small puzzle-blocks floating around in the grey (empty in my case :) ) mass. Some of these observations were;

- the watch ran only 7 hrs on a full wound.

- Before stripping the watch, I lifted the barrel-click and found hardly any residual power in the main-spring.

- Later I found the minute-wheel floating in thick oil, making me to assume that the combination of dirt, dried out and thick oil caused the watch to stop prematurely ........ coming to a grinding hold so to speak.

Obviously, if that would have been the case, there should have been some residual power in the spring left. I therefor jumped to the next "conclusion" that the spring must be "tired" after all those years. And to be honest, it never crossed my mind that a wrong spring could have been fitted !

The stamp in the main-plate say clearly 18SPB. Inside the spring-barrel sits a little hook, similar to the hook as on the arbor. Looking at JohnR725 pictures above, the hook seems suitable for a DBH spring. Also the barrel, as well as the barrel-lid do have slots to accommodate the DBH spring-"wings". The old spring removed has a "standard" end, found in many hand-wound wrist watches. So indeed, the spring mounted was the wrong type !! Again, very well spotted !!

From as far as I can measure, the inside of the spring barrel has a depth of 2.04mm, that's from the bottom of the barrel to the barrels edge. There is on the top of the barrel, on the inside, a small recess of about 0.4mm where to barrel-lid fits in. The thickness of the barrel lid is about 0.32mm. This means that if & when the lid sits flush with the top of the spring-barrel, the maximum spring height can be 2.04 - 0.32 = 1.72mm. The spring which I removed has a height of 1.84mm. This means that the lid couldn't have been flush with the barrel ....... a point I didn't observe.

Looking at scans of the GR book; am I reading correctly, under column 3, that the height of a 18SPB spring is 2.50 mm? If the original spring is indeed 2.50mm high, then something more is going on ........

If more information is required, please let me know what and I will try to provide .....

Hope to hear .......

Best regards: Roland

Edited by Endeavor
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Hi Roland,

It can be difficult to measuspring height from the barrel parts. According to the GR catalogue, the range of Omega 18 ligne movements has spring heights between 1.9 and 2.6, and typically there would be 0.1 to 0.2 clearance. Does the barrel lid have a recess which would add to the available space?

You could try refitting the original spring then holding the barrel between finger and thumb and the arbour with a pin vice to see if it winds and unwinds freely. This would tell you if you have sufficient space for it. You should also be able to see if there's enough space for a 2.5 which would seem unlikely - I usually work on the basis that whoever worked on a watch before me had some good reason for doing what they did and probably more experience. For what it’s worth I repaired a 19ligne Omega last year which had a standard spring fitted in a DBH barrel. The spring had broken so I had no choice but to replace it and I managed to find an appropriate DBH spring, but have no doubt that it must have worked fine for some significant time until the spring broke. The barrel size of my watch didn’t appear in the GR catalogue.

The barrel diameter is easier to measure and with that and the height using the calculator on David Boetcher’s watch stap site you should be able to find a good fit.

I spent hours searching on line for details of the different variants of 19 ligne Omegas and concluded that there were many more variants than were apparent from many parts catalogues. I decided I was better off working from analysis of the parts in front of me than expecting to find the answer served up on a plate for me...

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 @StuartBaker104: Thanks again for your valuable contribution !

I fitted the spring again. The top of the spring seems to be flush with the bottom of the lid-recess inside the barrel. The lid itself has indeed a recess inside, allowing for a slightly higher spring. The old-spring fitted has a height of 1.85mm, so I may get away with the minimum spring-height in the range you indicated, the 1.9mm. A 2.5mm high spring is for sure out of the equation.

With the spring mounted, and the barrel-lid pressed flush with the top of the barrel, the arbor (US ?, arbour = UK ?) turns freely and the spring winds / unwinds smoothly.

Omega-19.thumb.jpg.fd24932d07a4774992217a2b5a41903a.jpg

Omega-20.thumb.jpg.41ff8b78815c3225cc11abbe7f1c22ea.jpg

The inside of the barrel measures ID = 14.4mm. The flush OD of the barrel = 15.5mm.

I was wrong with my first internal height measurement inside the barrel. From the inside bottom of the barrel to the top edge = 2.36mm (measured with 0.02mm accuracy calipers to the best of my abilities) and the overall external height of the barrel is 2.6mm.

The thickness of the lid seems to fluctuate a bit, depending on where the measurements are taken, between 0.32 - 0.38mm. Lets assume on, to be on the save side 0.4mm. This would suggest that the internal height would allow 2.36mm - 0.4mm is indeed a 1.9mm high spring.

I'm not familiar with the mentioned David Boetcher’s calculator, so I may need some guidance there ....... :( 

Whether the watch has run correctly in the past is hard to find out, the owner has passed away and another mystery is why the sub-dial seconds hand is missing ....

Hope to hear you thoughts .....

Regards: Roland.

Omega-21.jpg

Edited by Endeavor
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Looks like we are about there then...

The David Boetcher page was the one I linked here http://www.vintagewatchstraps.com/mainsprings.php

Entering 14.4 into the reverse engineering calculator gives a spring of .177 thickness and 450 length.  Cousins has GR5617DBH which is 1.9x0.18x440x14.5 which looks close enough to me. Did you measure the thickness of the old spring?

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15 minutes ago, StuartBaker104 said:

Cousins has GR5617DBH which is 1.9x0.18x440x14.5 which looks close enough to me.

 OP mentioned barrel ID to be 14.4. This MS will not transfer straight from the holding washer.

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@StuartBaker104: I've been punching numbers in the "half-area" calculator. The arbor OD is 4.84mm and took an arbitrary 7 turns; the results were 0.16 thickness and 496mm long ...... but I trust your judgement better :) 

Yes, I measured the old spring with a micrometer and it was 0.19mm thick. But as written in the David Boettcher article; "repairers sometimes used whatever they had on hand that would fit", so I don't know how much value we should attache to the old-spring thickness?

@jdm: Could you please elaborate on your remark? Do I need to measure differently?

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3 minutes ago, jdm said:

 OP mentioned barrel ID to be 14.4. This MS will not transfer straight from the holding washer.

Yes - that’s a possibility, but mainsprings only come in 0.5mm increments of barrel diameter and measuring an internal diameter with a vernier caliper is not an exact science. In any case, the holding washer internal diameter is normally smaller than the stated barrel size.

It’s a bit tricky lining up a DBH spring end either way and it may be easier to hand wind it into the barrel.

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1 minute ago, Endeavor said:

 

@jdm: Could you please elaborate on your remark? Do I need to measure differently?

Washer ID 14.5 which is larger than 14.4. So, will not transfer directly. Up to you to decide if you want to install it anyway with a winder, or manually.

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I've no problem installing this spring manually. This barrel is humongous compared to for example a 7-3/4''' ETA2540 barrel. Having no winder leaves one with not many other options ;)

If the spring slides in, I'm lucky. If not, no problem ........ thanks for pointing out the possible hurdle.

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One minor problem possibly looking at my mainspring catalog I was pondering where you found the number GR5617DBH ? Having the complete catalog in hand going to the back I can look up the number and it's for an Elgin watch. The concern I would have is I don't know if the spacing between the hole at the end and the T part is going to be the same spacing. So you may want to stay with an actual Omega spring. So Omega has 5643 0.19 & 5619 0.18 both DBH. Both of the same length at 480 mm with just a difference of the strength which isn't going to matter.

At one time like American pocket watches there would be several different strengths possibly for the same watch. Usually because similar models would have different jewel counts there be different strengths for that.. Then modern Springs no longer blue in color different materials different hardening processes and almost always for the same thickness stronger. Then today usually there's one spring available versus the several of the past if you're lucky.

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1 hour ago, JohnR725 said:

So you may want to stay with an actual Omega spring. So Omega has 5643 0.19 & 5619 0.18 both DBH. Both of the same length at 480 mm with just a difference of the strength which isn't going to matter.

That’s a good call John. I don’t have the paper catalogue, so I used the search tool on Cousins website to find springs by size.  I did look for 5619 which was the nearest Omega, but not available. 5643 is available, but not in DBH form.

Perhaps explains the non DBH spring found here.

Unless one of the above can be found elsewhere I would still be inclined to get the 5617 and if the T end won’t fit, it could be cut off to just use the hook end.

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Not hampered by any knowledge and for my own education, I would like to ask the following questions; The full "CousinsUK" specifications of the GR5643 spring are: Height x thickness(strength) x Length x Barrel diameter:  1.90 x 0.19 x 480 x 15 None-Automatic.

From what I read on the David Boettcher website; the longer the spring, the more "linear" the "power-supply". But also, in this case my barrel ID is 14.4mm, there seems to be a kind of optimum "fill" (space occupied by the spring)  inside the barrel. "Un-coiling" the old spring which was fitted, I measured about 440mm (the last 10-15mm are a guesstimate since the last part of the spring is hard to un-coil)

My questions are:

- Even though a longer spring (GR5643: 480mm and meant for a 15mm barrel vs GR5617: 440mm for a 14.5mm barrel) may be beneficial, would the barrel not get "over-filled" with the GR5643 which is not only longer but also slightly thicker (0.19mm vs 0.18mm)?

- CousinsUK presents a nice drawing of the different spring ends; "Normal Bridle, DB, DBH, T & TR". The GR5643 Cousins has on offer is described as "Non-Automatic" ...... which they don't describe what that is ? Is that a "Normal Bridle", like the old spring I found in the watch?

- Now I'm getting on "slippery ice": The old spring fitted had, as I understand, a Normal Bridle, and the end-lip seems to engage nice firmly behind the DBH hook inside the barrel. I know, not as meant to be, but would a "Normal Bridle" spring not function just as well in a DBH barrel?

Edited by Endeavor
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Just to elaborate a bit on my last "slippery ice" question; If, as StuartBaker104 suggest, the wings of the GR5617DBH don't match up with the holes in the barrel, the wings could be clipped off and one would rely on the hook-end as being a sufficient anchor point. I get that and have no problems with his suggestion if that's what it takes.

Now I like to make the ice even more slippery and perhaps this question is only hypothetically; For me it seems that the end of a spring with Normal Bridle, as with the spring I took out, seemingly fits also nice tight & snug behind the hook inside the DHB barrel. If in the old days this practice was "accepted" and would indeed supply a sufficient anchor point for the spring, could one then, if circumstances dictate,  make a choice out of springs with a "Normal Bridle"?  Wouldn't this open up a whole host of new possibilities (different lengths, thicknesses etc)?

Please don't shoot me down in flames, I'm just testing the waters here ! :D

Edited by Endeavor
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Lots of questions here...

1. “Non automatic” is the standard hook end spring, or normal bridle.

2. As I see it, the “fill” is an arbitrary outcome of potentially conflicting requirements... not overstressing the spring by winding it too tightly around the arbour; not pulling the outer end of the spring away from the barrel wall when fully wound; providing enough power through a long enough spring to run the watch for 30 to 40 hours. (In days of yore, there was a further challenge around maintaining a more constant torque which was achieved through “stopwork” which prevented use of the maximum and minimum wind conditions).  Watch designers therefore need to concern themselves with fill, repairers can use it to help ensure they have the right spring by assuming the watch designer worked within standard parameters.

3. Spring thickness is a critical characteristic linked to the watch design. Torque will increase with the cube of the thickness and so small increases have a big impact. The torque should be sufficient to maintain a high balance amplitude without knocking (over banking). Within reason, at the design stage, the height can be reduced to achieve the optimum torque

4. So, 0.18 to 0.19 thickness will increase the balance amplitude slightly, but given the same spring length allow fewer turns and therefore a shorter run time. Adding length will overfill the barrel and may result in fewer rather than more turns. This difference of 0.01mm is reasonably insignificant, but I wouldnt want to go to a 0.2 spring if it could be helped.

5. The double brace and hole arrangement appears to serve 2 functions. Firstly, it holds the hole against the barrel hook when the spring is fully wound and secondly, in theory it spreads the load (although the likelihood of al 3 points being in contact seems low). Whether either is necessary with a modern alloy spring with a reverse final curve is a point way beyond my understanding. Clearly you could bypass all this effort and fit one like you found, but that’s not what the designer intended, and will we ever know all of the thought that originally went into this? 

Finally, I should say that I am an engineer who reads a lot and thinks a lot, rather than a qualified horologist... and every day is a school day!

 

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Thanks a lot Stuart for your elaborated answer ! All is written clearly in understandable language. Also importantly, no abbreviations are used, so everybody can understand. If you can teach and articulate this well, means that you understood the topic at hand and yes; all of it makes sense.

When I joint my previous profession (retired engineer now), the working culture "didn't appreciate" too many questions and one of the "standard" answers was " You don't know !??" (most likely hiding their own "unknown"). Obviously, in the beginning, you didn't want to look stupid, so one was careful with posting questions. Later and now I played / play as dumb as possible, ask as many questions as possible and learned / learn as much as possible. Every day is indeed a schooldays and a treat ! Thanks a lot :thumbsu:

I'll go ahead and order the GR5617DBH and perhaps it's exactly the right spring? If not, there are ways around and improvising becomes the key. I always love the latter ! ;)

Edited by Endeavor
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