Replacing vintage mainsprings: NOS or generic modern mainspring

Knebo · May 17, 2023

Hello folks,

When servicing vintages watches, I tend to try to source NOS parts. E.g. an Omega cal 244 from 1954. Getting an NOS mainspring in its original Omega packaging is possible. I've been doing this without much reflection.

However, I was now wondering if this is always the best approach.

Maybe a modern mainspring with the correct size (of course), e.g. from Generale Ressorts, would be more performant ! E.g. a potential increase in power reserve or even amplitude.

Any experience or opinions on this?

I couldn't find previous discussions on this topic. If there was, please help to redirect me.

Best regards,

CK

Jon · May 17, 2023

I try to keep away from mainsprings that aren't modern alloy and definitely stay away from NOS blue mainsprings because they are prone to have rust on them, which you can't see and this will lead to micro=fractures and breakages.

If I can't find anything else for a vintage pocket watch, then I have resorted to using blue mainsprings, but as a last resort.

Also blue mainspring sizes sometimes don't directly translate in strength to modern alloy mainspring sizes. I tend to come down half a strength when using an alloy spring as opposed to the original blue spring.

A strength is 0.01 mm in the thickness of the mainspring. Half a strength is 0.005 mm

So, if I come across a vintage watch such as a Felsa 690 with the original spring and slipping bridle, I will always replace it with a modern auto spring without the slipping bridle.

Some may want to keep originality, but I would prefer a good amplitude!

JohnR725 · May 19, 2023

On 5/17/2023 at 11:11 AM, Jon said:

NOS blue mainsprings because they are prone to have rust on them, which you can't see and this will lead to micro=fractures and breakages.

the unfortunate problem of rust. Yes blue steel mainsprings seem to attract rust set makes it sometimes difficult to get a usable spring. Then the micro fractures. The Elgin watch company had a paper once on that explaining that right thing storms do not cause mainsprings to break they break because I think they might've been suggesting if the watchmaker touches the spring of the oils and whatever on your hands will cause the micro fractures. I also think it was just how they heat treated the Springs. So often times with a vintage spring is they will shatter in your mainspring barrel I had that once happen with one of my Elgin's. I've also seen them shatter in the package they use come out a bunch of little pieces but if you can throw in a low rust we once had a Rolex watch with the mainspring shattered no idea of who is original or aftermarket.

So I would agree ideally I tried not the use of blued steel spring. But sometimes it can't be avoided. Sometimes the blued steel Springs Elgin and Hamilton for instance will come other packages absolutely beautifully they still have a beautiful back curve they look nice there's no rust but other times not so lucky.

Then there's the other problem of the case of vintage American if you look in the book you often see that forgiven part number it came a whole bunch of different thicknesses basically correspond to a seven jewel watch all the way to 21 jewel watch. Elgin even had mainsprings that were lighter than normal and those relisted in the early catwalks. I've even seen an internal document from Elgin where when the watch reached the final quality check of it had too much amplitude it would go back to the spring department were that swap barrels to get the amplitude back down to where it's supposed to be if the amplitude was too low and go back to the escapement department to adjust to get get to where it's supposed to be

of course that brings up the problem of some poor soul who gets that Elgin watch who puts the spring and the supposed to be and now it is too much amplitude.

But there is the tiny problem of the modern springs tend to be stronger for the same thickness as the blued steel Springs at least that's most discussion groups not everybody have heard somebody claimed that that's totally false. But the majority people find modern Springs are stronger. All those various sizes here like you to get anything today. When I order my mainsprings from the local material house I give her all the dimensions of the particular spring and I just say give me whatever you have that avoids the unpleasant call of I don't have these sizes will you take this all just take whatever she has and it always is worked so far plus I get my mainsprings

On 5/17/2023 at 11:11 AM, Jon said:

I will always replace it with a modern auto spring without the slipping bridle.

yes the minor problem of vintage auto winding watches with separate auto winding mainspring somewhere around here I have a paper from Omega where they commented their upgrading all the mainsprings to the bridal is attached and why that is so much better than the old method.

So ideally the modern Springs should be better. But sometimes you have to use a blued steel spring for a variety of reasons.

On 5/17/2023 at 9:47 AM, Knebo said:

Generale Ressorts

oh and then there's that. I think that's about the only company making mainsprings anymore at least that what we can purchase obviously the Chinese make mainsprings for the watches Seiko makes their score they buy them somewhere in Japan but the most common source of mainsprings whether they're in their packages or not is this company. I find a lot of times when I buy my American pocket watch springs it, package from somebody else but a lot of times ill have one of their numbers stamped on the internal packaging.

Knebo · May 19, 2023

Thanks @Jon and @JohnR725

Ok, understood: no blue steel mainsprings

So far, I haven't had those actually. My NOS replacement mainsprings were all for "less vintage" watches. 1950s onwards; nothing blue there. But still wondering if modern generic ones may be technologically better -- comparing 1950s alloys with today's alloys (leaving blue steel out of the comparison).

rehajm · May 19, 2023

Cousins has sent me one or two GS mainsprings in the little foil packs with added hairs and gunk. That's doesn't sound like an upgrade form a sealed NOS Omega, like for like...unless you like vintage stubble hairs...

GuyMontag · May 19, 2023

I ordered a replacement mainspring from Jules Borel for a manual wind FHF 324 and was looking forward to being able to just pop it into the barrel without having to use my mainspring winder. However, it turned out to be an old NOS mainspring that came in a huge tin drum wrapped in foil. It was *much* larger than my barrel so had to use my winder in the end. I would hope that if I order a mainspring and it doesn't say it's an NOS spring that I can count on it being a modern new spring.

Knebo · May 20, 2023

9 hours ago, rehajm said:

Cousins has sent me one or two GS mainsprings in the little foil packs with added hairs and gunk

What?! How is that even possible? The GS should be modern and properly sealed, no? Very strange.

7 hours ago, GuyMontag said:

would hope that if I order a mainspring and it doesn't say it's an NOS spring that I can count on it being a modern new spring

That's also crazy.

I live in Geneva, Switzerland, and I haven't even found a supplier of modern/new mainsprings! Out of all places in the world, this should be the easiest, no? But the ones I found only supply professional watchmakers, but nothing for hobbyists. Why is this so hard? Any advice for Switzerland (or France)?

JohnR725 · May 20, 2023

21 hours ago, Knebo said:

But still wondering if modern generic ones may be technologically better -- comparing 1950s alloys with today's alloys (leaving blue steel out of the comparison).

because you use the word generic then I can answer the question otherwise would have issues perhaps? In the case of both Hamilton and Elgin they had their own alloys of non-blued steel mainspring. Those even today are still outstanding mainsprings.

There's also characteristics of mainsprings that aren't necessarily published that will change things like the forming of the back curve of the mainspring. You take a mainspring of the package often times have a interesting back curve a lot of this is done to produce equal power a lot of generic springs may or may not have the same back curve.

the other problem is how well is a generic spring actually made I've seen brand-new White Springs that in the case of American pocket watch Springs I have to take them out of the package to get them in so I have to use a Winder and a lot of times they have? I vaguely recall one spring that basically was almost with nothing resembling a back curve another time one actually looked partially set it was just kinda spiraled out that makes you wonder how well some of the screens are being made.

I suppose it depends on who made the generic mainspring.

10 hours ago, GuyMontag said:

Jules Borel for a manual wind FHF 324

the problem with hearts is that it's it becomes complicated. Yes you have a mainspring catalog there is supposedly making mainsprings look at the date on that catalog it's very old. The Swiss like to keep reconsolidating for better well better watch making not necessarily watch spare parts making. The mania that is there slowly eliminating all spare parts so while yes at one time there catalog was filled with mainsprings the demand for all of those is limited slate no longer make all of who Springs. This means a material house will have to start looking everywhere in the universe and you will end up with older parts conceivably a lot of the back East material houses will purchase other material houses that might explain why you ended up with the spring you did they made a decision should they sell you a spring at all because it's not going to be a modern or should take silly of this one which will work

3 hours ago, Knebo said:

I live in Geneva, Switzerland, and I haven't even found a supplier of modern/new mainsprings! Out of all places in the world, this should be the easiest, no? But the ones I found only supply professional watchmakers, but nothing for hobbyists. Why is this so hard? Any advice for Switzerland (or France)?

now you know why most people on this group do business with cousins. Because they'll ship their parts to anybody they don't care. You might try the link below it's in Germany. Otherwise eBay is a good source for watch parts. then your problem is not unique a lot of material houses will not sell to hobbyists. Some of them at least in this country has to do with tax issues. Sales tax is supposed to be collected on the final sales in other words you purchase the parts you put them in the watch you sell the watch repair that would be the final sales so they don't collect taxes on parts. At least that's the excuse one of the material houses in Seattle uses not the sell parts to hobbyists. But even then there's ways around that.

But sincere in Switzerland they used to have shops that you can purchase used tools in. Because after all they have a lot of tools for manufacturing watches in Switzerland and I don't think those places necessarily discriminate against hobbyists versus professionals?

https://boley.de/en/shop/1.watch-spare-parts

praezis · May 20, 2023

2 hours ago, JohnR725 said:

https://boley.de/en/shop/1.watch-spare-parts

Boley sells and shows prices to professionals only.

Frank

JohnR725 · May 20, 2023

5 hours ago, praezis said:

Boley sells and shows prices to professionals only.

near as I didn't look at that I know there's online material houses in the US were I looked up something it's at all this company has it and then sure enough they don't sell to anyone but so-called professionals. Sometimes there is ways around it if you look up what the actual definition of a professional is like if you have a business license and it's not a watch repair business they will still sell to you for instance.

Fortunately for a lot of material there is eBay and they will sell to anybody

oh and for all the hobbyists unhappy that the professionals comply whatever they like that's not true either is a whole bunch of watch companies that will not sell to just about anybody you have to be authorized to get their precious spare parts. And then there's companies like Swatch group where you have to meet requirements if your requirement meeting changes you can get downgraded and then you can't access any of the technical information anymore I is to build a get access to Swatch group stuff through somebody and one little thing changed and now all we can access is non-technical information sort of. Then the person can't even place a parts order because his credit card expired and he doesn't know who to contact you Swatch group is just too darn big. So is not just the hobbyists that have problems the professional have a problem and then a course Rolex won't sell parts just about anybody even if you are professional even if you once had a parts account you may not bill a by Rolex parts ever again because they keep changing their guidelines because they can.

Knebo · May 22, 2023

On 5/20/2023 at 1:14 PM, JohnR725 said:

now you know why most people on this group do business with cousins. Because they'll ship their parts to anybody they don't care

Cousins! I was blind, and now I can see...haha. I knew about them, of course, but prematurely dismissed them because I though that taxes, duties and shipping from the UK into the EU or Switzerland would cost too much for the individual small parts that I usually need. But now I looked concretely for something and realized that shipping is free and taxes are calculated at checkout (and not much). So great!!! I hope I won't have a bad surprise when it's delivered with an additional customs processing bill -- but hopefully not.

Back to my original question and now my concrete example.

I have an AS 574 movement from the 1930s. Hard to get an NOS mainspring for that... and even if I do, I assume that modern mainsprings may perform better.

But thanks to WatchGuy (https://watchguy.co.uk/cgi-bin/mainsprings), I was able to find the (hopefully) correct Generale Ressorts reference (=GR 4474). I assume that this modern mainspring would somehow be "better" than an NOS one.

When searching/ordering this Generale Ressorts mainspring on Cousins, I also saw that the AS 574 calibre is explicitly listed as a compatible movement.

So yea, for individual and specific parts, Cousins it is!!

On 5/20/2023 at 1:14 PM, JohnR725 said:

Otherwise eBay is a good source for watch parts.

I agree, most things I find+buy on eBay. However, specific and individual parts (in this case: a mainspring) for less common (or very old) movements is difficult.

On 5/20/2023 at 1:14 PM, JohnR725 said:

But sincere in Switzerland they used to have shops that you can purchase used tools in

Sure, there are a few shops, but less and less... and, like eBay, they also don't often sell individual+specific parts. And often they are quite expensive vis-à-vis eBay. It's certainly difficult for them to sustain their business with the eCommerce competition.

For tools, like screwdrivers etc, I'm also guilty of buying mostly on Amazon (there's a great Amazon Marketplace seller in the region) with delivers fast and at good prices. So, unfortunately, I'm not really helping those local shops, either. I got Horotec hand levers from a local shop once, but it took them 1 week to get and it was a hassle to go to the shop in the middle of town (parking...) during their working hours (I have a day-job next to my nightly passion of watchmaking).

JohnR725 · May 22, 2023

2 hours ago, Knebo said:

I have an AS 574 movement from the 1930s.

as you're learning you'll find there's all sorts of references out there for finding parts. Like the bestfit book you can find it on physical form usually on eBay or PDF somewhere in the universe really interesting book for referencing parts. Then there is the website at the link below helpful for getting numbers. Also the mainspring catalog can be downloaded as a PDF.

not a lot of parts information for your watch but I do see a mainspring that's at the second link

third link is the mainspring and we get a part number which I always consider a bestfit number sort of. Then all the watches that cross references to plus the size. Depending upon the watch sometimes various sites will have slightly different sizes of a mainspring.

then once you get your number you go to their home page for you find out that the prices going up they do worry about that the prices are not valid looks like it's available.

then you make a modification like drop off the first letters of the best fit part. Go to eBay and do a search for mainspring 711H. Look what you find mainsprings they're available some of them are relatively cheap.

oh and numbers on the mainspring packet I wonder what they mean? Watchmakers are interesting when it comes the measurements their creative they use whatever is available. This is why for instance mainsprings can be measured in Denison, metric and inches or fractional inches and all of those could be on the same package or a combination of them. So I'm attaching a PDF of cross reference for Denison to something else. Plus the catalog shows the various types of ends of mainsprings. Lists all the various American mainsprings which brings up a problem if you look at a parts catalog for those companies at one time they came in way more thicknesses than they do now. Then you get the automatic mainsprings plus mainsprings with special ends on them. then the rest of the book whereby seen those numbers before? like the 711 H is listed. Plus if you look at the number is what you'll see is the number is basically the Denison number of the mainspring with the last letter referring to the length. So is always possible if you can find the exact spring in need because it doesn't exist you could have variations possibly and get something either shorter or longer.

http://cgi.julesborel.com/

http://cgi.julesborel.com/cgi-bin/matcgi2?ref=AS_574

http://cgi.julesborel.com/cgi-bin/matcgi2?ref=qWLXEk

http://www.julesborel.com/s.nl/it.A/id.28723/.f

Mainspring - DennisonChart.pdf Mainsprings Cas-Kar Catalog 2018.pdf