Mainspring for JLC

[Jtalleruphuus]

Hello

I have a Jaeger LeCoultre from 73 where the mainspring is broken. My watchmaker measured it to: H 0,95 x 0,10 x ø 10,0 x L 360. However, i can't seem to find one close to those measurements anywhere. Can anyone help?

/Jacob

[Endeavor]

Your "watch-repairer" can't help you and lets his client to find out ??

You need to know what kind of tail end it has; automatic or none-automatic (NB, DB, DBH, T or TR)?

If you can't find the correct spring, you can use the reverse engineering estimate calculator in this website;

http://www.vintagewatchstraps.com/mainsprings.php#

then you go to CousinsUK and find the closest in thickness and length with the correct tail end and correct height.

https://www.cousinsuk.com/product/under-100mm-height

In your case, the height has to be 0.95mm (or slightly lower) otherwise you can't close the lid of the barrel. The length and thickness can vary a bit. Thinner is slightly weaker, thicker slightly stronger which could cause knocking or banking.

Perhaps it is also a good idea to introduce yourself first, so we get an idea who you are and what kind of watch skills you have .... ?

 

[Nucejoe]

The owner of JLC 73,    welcome. 

 

 

[JohnR725]

5 hours ago, Jtalleruphuus said:

Jaeger LeCoultre from 73

It would've been nice if the watchmaker had given you a model number? Then is this an automatic versus manual wind watch? The problem with finding specific parts is the part you're looking for may be the wrong part which is why you're not finding it. That's why it's better to start with the basics of the model number the watch we can look it up in our references and see if they all agree. Plus it's also helpful to measure the original spring to make sure that agrees with whatever you are finding in the specifications. Occasionally we get some strange watches were nothing agrees Which makes things much more interesting.

[praezis]

Watchmakers normally don't measure the old spring, as it might be already wrong, but determine the movement calibre and look up the correct spring in tables. 

Frank

[JohnR725]

2 minutes ago, praezis said:

Watchmakers normally don't measure the old spring, as it might be already wrong, but determine the movement calibre and look up the correct spring in tables. 

I like the word normally? This is watch repair there is no normal.

So normal I assume means modern then you're right. In modern watch repair you can look up the part all the parts and 99% of time they will fit perfectly. Typically modern watchmakers are attempting to restore the watch to new condition with their new parts they don't worry about what's in their.

But what about watchmakers like me? I primarily specialize in antique watches some of those don't have markings there is no caliber number I can't look up the mainspring. Or American pocket watches for instance there tends to be variations. So it's very helpful to start with what is in the watch. It doesn't mean that that's right but it gives you starting point. So I measure every single spring I take out. I verify that whenever I took out agrees with whatever the books think is supposed to be in there and if they don't then I need to find out why.

 

[praezis]

Hi,

first, my post was no reply to yours, just a few seconds later.

Is this an antique watch? .. from 73 did not sound so. For comparing it is not wrong to have the sizes of the existing spring, but I would not use them for finding the new one. If calibre and references are not  available, I use to take the sizes from the barrel and apply general rules to find width, legth and thickness of the spring.

Frank