# Balance Spring Distortion.



## ValvesRule (May 20, 2009)

I have a pocket watch with a cheap Chinese movement (centre seconds, fully jeweled Swiss lever, 6 B.P.S., crown set/wound, sort of barred... you know the one), and for no apparent reason a distortion has developed in the balance spring which causes the watch to run at about 1 1/6 speed (approx. 7 B.P.S.), and the balance amplitude to fall to less than 100 degrees pk-pk.

This can be solved by moving the regulator (curb pins only - no arm) off the fast end of normally-curbed region of the spring. This removes the distortion, but causes the watch to gain about a minute an hour.

I have regulated the watch from time to time.

Can anyone suggest a method of repair, or at least explain why this has happened?










In the photograph is visible the "normally-curbed region of the spring" as the end of the outermost turn of dramatically greater radius. This is to allow for the curb pins.

The distortion involves the outer three turns.

The watch was photographed running.


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## Mikrolisk (Jan 23, 2008)

Maybe the hairspring got magnetic?

Andreas


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## ValvesRule (May 20, 2009)

Mikrolisk said:


> Maybe the hairspring got magnetic?


This is, in fact, exactly what has happened. It resolved itself a few minutes ago.

I have been using a steel screwdriver to regulate it.

Thanks, Microlisk.


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## ValvesRule (May 20, 2009)

Sorry about the bump.

The distortion reappeared shortly after the last post.

What are ways/is the way of dealing with this?

I know that magetised C.R.T. shadow masks eventually demagnetise themselves, will the same thing happen to this spring? If it will, it's taking a long time.

And should I keep it running or stopped?


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## tomshep (Oct 2, 2008)

Shadowmasks "demagnetize themselves" through the action of the degaussing coil wound around them, which is pulsed on switch-on of the set Tha is, they don't. Making a demagnetizer is simple enough. Wind some wire over a tubular and non-magnetic former (say 2-300 turns of 7/.012and 4"dia.) and supply it through a momentary contact switch with AC from, a transformer around 24V at a couple of Amps. Old ones ran from mains with a 40 Watt bulb in series but Putting the sun in a bottle is sorcery and the green people want there to be a law against it which means it won't work with the low energy (low output, high environmental cost, non-recyclable etc.) ones. It is a technique also considered unsafe these days by those who are too stupid to take care of themselves. Nurse! My medication...

The object to be demagnetized is passed through the tube and drawn away from it some distance.


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## ValvesRule (May 20, 2009)

Thanks, tomshep.



tomshep said:


> ... 4"dia.)...
> 
> The object to be demagnetized is passed through the tube and drawn away from it some distance.


So, I can just move the whole Watch through - I don't have to remove the Balance Spring?

I had considered an electric demagnetiser, but the only ones I knew about were tiny ones for magnetic tape heads.



> It is a technique also considered unsafe these days by those who are too stupid to take care of themselves.


One amongst many, many others.


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