Mainspring acting weird!

[EatPeach]

Hey guys. One of my non-automatic mainspring is acting weird in the barrel. It's hard to describe but the mainspring wont stop and keep winding and flexing inside the barrel.

Here's a demonstration.

 

So after the mainspring crosses the line where it should stop normally, it curl to one side of the barrel and keep winding.

What happened? How can I fix this one?

Thank you!

 

 

Edited July 9, 2020 by EatPeach

[eccentric59]

Sounds like the spring was over-wound and the bridle was either bent, broken or fatigued. Have you taken the spring out and inspected the end closely? It might be time for a new mainspring.

[EatPeach]

Just now, eccentric59 said:

Sounds like the spring was over-wound and the bridle was either bent, broken or fatigued. Have you taken the spring out and inspected the end closely? It might be time for a new mainspring.

Thank you, I'll take that out and chek it tomorrow morning. Is this a common issue? I just can't come out any reason how the ms is bent.

[eccentric59]

I would expect over-winding a manual watch is fairly common, but what happens then would depend on how the mainspring is secured in the barrel. There are many different types. I'm guessing that you have the Swiss tongue end, which looks like, when wound too tightly, might bend and deflect the spring as you describe. A different style might simply break under those conditions.

 

[EatPeach]

1 minute ago, eccentric59 said:

I would expect over-winding a manual watch is fairly common, but what happens then would depend on how the mainspring is secured in the barrel. There are many different types. I'm guessing that you have the Swiss tongue end, which looks like, when wound too tightly, might bend and deflect the spring as you describe. A different style might simply break under those conditions.

 

yeah it's a regular swiss end. So if the bridle is bent, can I manipulate it back, just like what we do to the hairspring?

[jdm]

1 hour ago, EatPeach said:

 It's hard to describe but the mainspring wont stop and keep winding and flexing inside the barrel.

Yes it can happen with brand new, roundel-contained mainspring. The end needs to be bent just so slightly to engage the machining in barrel wall. 
I'm not sure if there is a way to find out before one closes the lid on it but certainly that's is on my due diligent list when working on the the next hand wound watch,

[eccentric59]

51 minutes ago, EatPeach said:

yeah it's a regular swiss end. So if the bridle is bent, can I manipulate it back, just like what we do to the hairspring?

Maybe. If it's a relatively fresh bend with no damage to the steel then you should be able to adjust it. But, if there are any signs of fatigue, then it's going to break on you sooner than later. Better to replace it now that you have it apart, IMHO.

[EatPeach]

The bridle look like this

[EatPeach]

13 hours ago, eccentric59 said:

Maybe. If it's a relatively fresh bend with no damage to the steel then you should be able to adjust it. But, if there are any signs of fatigue, then it's going to break on you sooner than later. Better to replace it now that you have it apart, IMHO.

looks pretty normal to me. Is it bent?

[watchweasol]

Hi  As EP says looks normal. the

[KarlvonKoln]

Don't mind me.  I'm just following this thread and learning some things.

[EatPeach]

Hi  As EP says looks normal. the

Yeah I wonder what cause the problem. Maybe the spring is fatigue？

[EatPeach]

Don't mind me.  I'm just following this thread and learning some things.

lol sure. We learn together

[eccentric59]

Looks okay to me. I might think it should follow the contour of the barrel a little closer, but then not too much or it could slip off the stop. But, that's not your problem, right?  You're saying that when fully wound the back of the spring lifts off the barrel.

[EatPeach]

1 minute ago, eccentric59 said:

Looks okay to me. I might think it should follow the contour of the barrel a little closer, but then not too much or it could slip off the stop. But, that's not your problem, right?  You're saying that when fully wound the back of the spring lifts off the barrel.

Yeah it does not slip actually. Is just the bridle and the end of the spring will not cling the barrel wall and keep wind up

[eccentric59]

The reverse curve of the spring is supposed to keep the tongue pressed against the barrel. Perhaps the spring is simply too weak? (Just guessin' here).

[EatPeach]

Just now, eccentric59 said:

The reverse curve of the spring is supposed to keep the tongue pressed against the barrel. Perhaps the spring is simply too weak? (Just guessin' here).

that might be possible. Let me change a new one and check the performence. I dont see any significant issue with this mainspring, I dont even know how to start it. So best to change a new one

[watchweasol]

Hi Just a thought  Is this spring origional it might be a GR spring and the bridle is a bit soft, The bridle should be quite stiff (tempered) so it contacts the stop with no bending or flexing.  

[saswatch88]

it seems like the spring is way to weak....a spring with correct strength for the barrel should be sitting a lot closer to the barrel wall, and the bridal should have more curvature to it which also not helping with the situation, so i would get a pair of round shank beading pliers and curve the bridle a bit more then see if it slips.

Edited July 10, 2020 by saswatch88

[praezis]

Sounds like this is just a totally wrong mainspring.
Do barrel diameter, spring length and thickness  match?

Frank

[EatPeach]

1 minute ago, praezis said:

Sounds like this is just a totally wrong mainspring.
Do barrel diameter, spring length and thickness  match?

Frank

it's an original mainspring…… Not if someone swap it and I dont know