Off-centre Hairspring

[Jonno65]

Hi All

 

I bought an NH35 Movement recently that came with a second one that wasn't running.  It was fairly obvious as to why, that being an off-centre hairspring.  I swapped the balance assembly and both movements run with the ok balance assembly.  I've order a replacement but want to know if it's repairable.  I am wanting to know if its a spring adjustment required as it doesn't look bent.  Pic below indicates issue.  the bottom pivot (top when fitted) is in it's bearing hole. Thoughts?

Also, tips on removal.  It's sacrificial so more of a training exercise.

[Nucejoe]

Its repairable, perhaps kinked where its in the regualtor slot, move regulator arm to expose where is now in the slot, streighten the kink, reshape the terminal curve, your quality check and final adjustment is when installed. 

Good luck

[mikepilk]

Should be a relatively easy* fix. As Nucejoe says, it's kinked due to the Etachron adjuster being turned too far.

It may be that simply turning the adjuster fixes it, but if it is kinked you will have the bend the it back to shape.

* As with anything to do with that hairspring, even "easy" fixes can soon lead to disaster. 

[Neverenoughwatches]

3 hours ago, Jonno65 said:

Hi All

 

I bought an NH35 Movement recently that came with a second one that wasn't running.  It was fairly obvious as to why, that being an off-centre hairspring.  I swapped the balance assembly and both movements run with the ok balance assembly.  I've order a replacement but want to know if it's repairable.  I am wanting to know if its a spring adjustment required as it doesn't look bent.  Pic below indicates issue.  the bottom pivot (top when fitted) is in it's bearing hole. Thoughts?

Also, tips on removal.  It's sacrificial so more of a training exercise.

As mike and Nucejoe have said the etachron adjuster at the timing regulator may only need adjusting to straighten out the end curve at that point. As you can see the hairspring is bending outwards as it enters it and bending inwards as it exits. This should hopefully recenter the hairspring as long as there is no damage to it. Better to do the adjustment while in the movement.

[JohnR725]

17 hours ago, Nucejoe said:

ts repairable, perhaps kinked where its in the regualtor slot, move regulator arm to expose where is now in the slot, streighten the kink, reshape the terminal curve, your quality check and final adjustment is when installed. 

One of the things you want to remember when you're doing the suggestion above is you also want to put it back in the watch. Nice for getting pictures when it's out of the watch upside down but the balance wheel may be leaning which changes how things look you also can't tell when you're fixing the terminal curve whether you're going to cause the hairspring to go out of flat.

[Jonno65]

40 minutes ago, JohnR725 said:

One of the things you want to remember when you're doing the suggestion above is you also want to put it back in the watch. Nice for getting pictures when it's out of the watch upside down but the balance wheel may be leaning which changes how things look you also can't tell when you're fixing the terminal curve whether you're going to cause the hairspring to go out of flat.

Totally agree - the balance assembly will be back in the movement.

[JohnFrum]

July 1996 issue of the horological times has an article by Archie Perkins that goes into centering hairsprings on the balance cock.

Sep 1995 issue has articles by Perkins and Fried on hairspring manipulation  

Edited February 15, 2023 by JohnFrum

[Jonno65]

Thanks for all your help on this.  I ended up buying a spare balance complete.  I completely disassembled, cleaned, lubricated and reassembled the NH35 movement, then regulated it!  Justifiably satisfied with myself!  Took me a few nights, and a couple of times I had to walk away for a bit, but its now a runner!  Now to but a case, dial and strap to make my own watch!