The Breitling Watch Source Forums

Right please excuse my lack on knowledge on this subject. I am trying to teach myself a bit of horology as I am very interested in the subject. I bought a few old watches that don’t work with the idea that I'll just take them apart and put them back together again to get some experience. Now I'm pretty happy with that I was thinking maybe I should try and fix one.

I have narrowed one down and have figured out its the balance spring that is causing the problem, but this is where I get a bit stuck I've searched the web but not really sure what to look for so I thought I'd ask on here.

Is there any particular type of balance spring for certain watches or are they all the same? I can only guess that there are different lengths etc?

Please don’t be too harsh

Thanks

Chris

Balance springs have infinite number of variables - length, material, terminal curve, etc. Balance springs also wear out and trying to 'mend' a balance spring is not really a viable option. The best solution to start off with is to buy yourself a copy of 'Bestfit' which is essentially a parts catalog and then order yourself a balance complete that matches your movement from one of hte supply houses.

However, are you absolutely sure that the balance spring is the problem rather than something else in the running train? Typically the balance will exhibit thesymptoms of a problem anywhere in the running train but the actual cause could be anywhere from the mainspring out and could be everything from an incorrect or broken mainspring, a depthing issue with the wheels, a lubrication issue, etc, etc.

Ahh doesn't sound like an easy thing to figure out then. Okay I'll have to have a look into that, guessing you can get them off eBay?

I think it is the balance spring. The spring was bent out of shape and when i gently moved the pallet back and forth like the balance wheel would do and everything works as it should do.

Pallet fork is driven by the escape wheel through the running train, not by the balance. You can likely get Bestfit on eBay.

If you put a small amount of pressure on the pallet fork it swings over to the other side is that right? Okay thanks I'll have a look.

Before you say anything I know I've got a lot of theory left to do

Briefer than it deserves because my already bad typing is worsened by being on a phone, but.......

The mainspring has the power for the watch stored in the form of a tight spiral. As the energy is released by the sping becoming unspiralled (!) It rotates the mainspring barrel which in turn drives the running train - the wheels that drive thearbors that the hands mount to. The last wheel in the running train is the escape wheel which engages with the apllet fork.

If there were only the wheels then the watch would run down almost instantly as the mainspring drove the running train - the hands would whirl around very fast and then stop as the mainspring wound down. The pallet fork engaging with the escape wheel stops that from happening by 'locking' the escape wheel and stopping the running train. The apllet fork rocks on a central pivot and is moved by the energy from the escape wheel. As it rocks one way the pallet fork transmits power into the balance wheel which rotates tightening the hairspring (balance spring). When the stored energy in the balance spring overcomes the momentum of the balance wheel the wheel starys to rotate in the other direction and eventually will cause the pallet fork to rock the other way allowing the escape wheel to rotate one more step and causing the watch to 'tick'.

So..... the hairspring acts on the balance to keep the watch moving, but without impetus from the mainspring it will only ever run for a few ticks and then stop. Replacing the balance complete (wheel and hairspring) is not a bad idea, but if there is an issue in the running train then it won't help.

Hi

As Roff said its not as easy as just replacing the balance their are different things to consider length and size also then it needs regulating to get it into beat then you need a timing machine.

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