Hair springs - repair or replace

[StringyBob]

Hi - I'm very much a newbie to all this... I have a few old-ish (up to 200 years old) pocket watches, nothing expensive, which I bought to play around with. I've stripped them down and re-assembled them (just for fun). A few clearly had problems with the hair spring, from simply being off centre or tilted to having a nasty 'kink' in it.  I realise it is possible for someone with experience to sort out some hair spring problems... But is the general advice for newbies to buy a replacement, if this is the case, where do you look? I've come across suppliers of all manner of replacement parts, but in general they don't seem to stock hair springs!  Is this because it is tricky to find an exact match and the standard advice is to track down a similar movement sold as spares and hope the hair spring is ok.... Or is it that hair springs aren't sold alone and you would normally buy the whole balance assembly..?

Thanks

 

[RyMoeller]

Hello Bob,

Well, it's usually easiest to replace the entire balance assembly if the hairspring is missing or damaged beyond repair as the hairspring has been vibrated for particular balance. When you replace just the hairspring on a balance you'll usually have to cut the replacement to the proper length to ensure it swings the balance at the right frequency. This can be particularly difficult if you are replacing an overcoil hairspring.

Fortunately complete balance assemblies are not too difficult to come across for most 20th century watches. Unfortunately, they are usually pricey.

For much older watches (19th century and earlier) I think you would probably have to either find a parts movement to scavenge a balance complete from or vibrate are replacement hairspring.

There are tools out there to assist in vibrating hairsprings but again they can be pricey and you would need to find the tool which is tuned for the watch frequency you'll be working on (ex. 18,0000 bph). There are also tools out there for forming an overcoil- I've been trying to score some Dumont tweezers for this purpose but again they are pricey.

If you are working on American pocket watches, I know some of the manufacturers did produce replacement hairsprings.  Many NOS Elgin hairsprings can be found on eBay.

Some suppliers also sell uncolleted hairsprings which can be used by an advanced watchmaker to replace a damaged or missing spring. I believe Otto Frei sells uncolleted springs.

Personally I always try to fix a damaged hairspring. If it's already broken then it's hard to feel bad about making it worse- especially if there is no other option. You'd be surprised what can be accomplished if you just keep plugging at it. The first watch I repaired involved mangling the hairspring and then sorting it out. I also think it's the greatest thrill in watch repair- bringing a dead hairspring back to life.  

[nickpeh]

Replacing the entire hairspring seems good choice, but is there a easier way to determine if it's perpendicular to the balance cock and the base plate? I often encounter the issue of hairspring knocking or rubbing against something, when put on timegrapher , so many of those dots lying around...

[StringyBob]

Thanks for the replies (sorry for the delay, I've been away for a few days) - I've tracked down a few donor watches in amongst a job lot of 'scrap' on Ebay, so hopefully the transplants will work