Replacement balance spring on Verge Fusee

[bobolink]

I am replacing a balance spring on a verge fusee.  I have the dimensions length, height,  thickness, etc. and have created the jig for dimensioning a piece of piano wire and the flat tweezer for curling it per The Selective Luddite.  It was not easy but it worked with some twists and turns. The difficulty was in the curling process and keeping the curls flat.

After doing that my question is a general one. 

Rather than go this route would a NOS pocket watch balance spring of the same dimensions work just as well?  Even if it was longer with more turns but the same diameter?

I know the one I created has 5 turns and most newer pocket watch springs have more. 

Has anyone tried to dimension an existing balance spring to a specific diameter and with less turns? For example take a spring of the same height and thickness with 12 turns and a diameter of 8.5mm and make it 7 turns keeping the same diameter of 8.5mm?

 

Thanks,

bob

[Neverenoughwatches]

1 hour ago, bobolink said:

I am replacing a balance spring on a verge fusee.  I have the dimensions length, height,  thickness, etc. and have created the jig for dimensioning a piece of piano wire and the flat tweezer for curling it per The Selective Luddite.  It was not easy but it worked with some twists and turns. The difficulty was in the curling process and keeping the curls flat.

After doing that my question is a general one. 

Rather than go this route would a NOS pocket watch balance spring of the same dimensions work just as well?  Even if it was longer with more turns but the same diameter?

I know the one I created has 5 turns and most newer pocket watch springs have more. 

Has anyone tried to dimension an existing balance spring to a specific diameter and with less turns? For example take a spring of the same height and thickness with 12 turns and a diameter of 8.5mm and make it 7 turns keeping the same diameter of 8.5mm?

 

Thanks,

bob

I watched a video a couple of years ago of a guy that did just this. Try a YouTube search .

[nevenbekriev]

11 hours ago, bobolink said:

 I have the dimensions length, height,  thickness, etc. and have created the jig for dimensioning a piece of piano wire and the flat tweezer for curling it per The Selective Luddite.

After doing that...

 

Hi Bob, I bet that actually You didn't try it, yes?

[bobolink]

Oh Neven you have no faith   Pictures attached.  Your correct in that I have not yet put it in the watch, it still requires straightening.  But was asking that question to see if there is a better way to create the spring.

I attached a pic of the joig I made and the spring and tweezers.

[nevenbekriev]

See, the things are not that simple. Well, in a verge watch where the spring has only 4-5-6 turns and balance amplitude is about 60 degr., the things are much easier. But the strip has to be uniform in thickness in all of it's lenght or other vice there will be places where it bends more than on others and will have strange behavior.

I have made strips for hairsprings from guitar strings on the lathe. The idea is to turh a perfect cylinder surface, then to wind the string tight on this surface and fasten it firmly, then turn the surface of thus coiled string in order that the cross-section will change from 'O' to 'D' in shape, then release the string and wind it again, but with the flat side to the surface and then turn it to shape finally the strip with the desired thickness.

The spring is easy to form by winding it on a rod between 2 washers and use coper wire(s) for the spacing between coils, then heat the whole thing to 300 degr celsius to fix the shape.

Another (easy) way is to form the spring by tweezers like You did. In russian schools they (used to) teach the students to work on hairsprings by making them straighten ladies movement hairspring to straight line and then turn it again to normal shape that will work perfectly in the movement, just using regular hairspring tweezers. So this is funny that one will have problems with verge watch hairspring forming...

Of course, the easiest thing is to take regular hairspring for pocket movement with the closest dimensions (thickness) and use it to form the desired shape for the verge hairspring.

You will be able to say that You have it done only when You have the movement working with correct frequency. Have in mind that in verge watches own balance frequency is significantly slower than the real frequency of the working movement. There is not a rule, as things depend on too many variables. But, for example, if needed frequency for the movement is 130 oscillations per minute, then You vibrate the hairspring to obtain 100 free oscillations per minute, then in the movement You will find that the balance will oscillate with about 120 and then You will gradually shorten the spring to obtain 130 when regulator in middle position. The shorter the spring is (the smaller count of turns), the bigger the degree of regulation by the regulator.

Edited June 22, 2024 by nevenbekriev
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