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Posted

I have been working on a valjoux 7740 chronograph and found quite a few problems with it. Already we are over budget on parts, but that's how it goes sometimes. The barrel was very worn and all the teeth were worn to around half length on another wheel. But now the watch is running fine I just have the Flyback lever to deal with.

 

It is common for flyback levers to break where it is bent down 90ºs in order to engage the reset pusher but unfortunately the flyback lever for the 7740 is obsolete, can't find one on ebay so I thought it would be fun to see what I can do with the broken one.

 

Not sure how this will pan out as I have not finished it yet but in theory this should work. Whenever I think outside the box like this I always try to think of non-destructive ways to execute the job so that it can be reversed easily if required. In this case, I am not modifying the watch movement in any way - just the broken flyback lever - this way, if a flyback lever is ever found in the future then it can be fitted with no problem and my modification discarded.

 

As for recycling - I decided to use an old watch back for the material, because - why not?

 

 

This is where the flyback lever goes...

 

post-1-0-39188200-1436864807_thumb.jpg

 

I softened the original flyback lever and drilled a hole - I am going to rivet an angled piece in order to engage the lever with the pusher.

 

post-1-0-44282800-1436864840_thumb.jpg

 

So I cut a piece out of a watch back :)

 

post-1-0-32975200-1436864912_thumb.jpg

 

Bent it about 90ºs and drilled a hole in it for the rivet.

 

post-1-0-89676900-1436864966_thumb.jpg

 

Turned a rivet on the lathe...

 

post-1-0-58035200-1436865016_thumb.jpg

 

And tried it all for size...

 

post-1-0-81923100-1436865075_thumb.jpg

 

So I now have to re-harden and temper the lever, then rivet the material to it, clean it all up, and give it a test.

 

This may not pan out - but it's fun thinking outside of the box. I will update the thread to let you know wether it worked or not.

 

 

What about you - any "out of the box" repair stories to share?

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Posted

I'm looking forward to seeing the end result already. :). The way things are heading,my out may have to do more of this in the future. :(

Posted

Now this is interesting... your "thinking out of the box" is what I like the most about watch repairing: sometimes parts are just nowhere to be found, and that's the only way you can make an old timepiece come back to life...  :thumbsu:

 

Will keep an eye on this thread to see the outcome, which I already know will be successfull.

Posted

Indeed - hopefully other people will contribute with their out of the box thinking :)

 

It's what keeps the job interesting!

Posted

Yep - £100 would push this job way too much over budget considering what I have spent on it so far

Posted

Well - it turned out OK.

 

Initially my rivet was fouling the screw and the hammer but a bit of whittling sorted it out.

 

Riveted in place...

 

post-1-0-70043800-1436870344_thumb.jpg

 

 

Just a bit of cleanup and it will be fine - functionally it works perfectly.

 

post-1-0-24448900-1436870345_thumb.jpg

 

post-1-0-76653100-1436870345_thumb.jpg

  • Like 3

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