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valjoux 7730 cam screw hole to wide

jasonphares
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jasonphares New Member

jasonphares

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hi chaps I have got on my bench a valjoux 7730 moment with chronograph issues. so I opened the case back and the cam screw used to adjust the pitch of the cogs fell out. I put the cam screw back in its hole but it should friction fit into place but unfortunately it fits in loosely hench why it fell out. any advice on how it close the hole up enough so it will hold in place again. I have mark in the image which one is the issue

Screenshot_20200718-095941_Photos.jpg

nickelsilver Distinguished Member

nickelsilver

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You need to punch the hole with a convex punch about twice the hole diameter to close it. But you need to disassemble the watch to support the other side properly with a stump in the staking tool.

If it's your own watch and you don't mind a bit of a hack job you can slide a piece of hair in the hole. This is utterly unprofessional but might get you enough friction so it's functional.

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HSL Distinguished Member

HSL

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That excentric setting screw (ES-2) is sitting on the barrel bridge if my memory don´t fail me.
It regulates the distance of the intermediary wheel teeths, normaly one leaves these alone if one isn't very used to work with chronographs.
Since they are friction fitted one really dont have many options to work with when the hole has become too wide. 
One is to fill the whole with new material, silver soldering, and drill a new hole.
Next would be to buy a new barrel bridge and replace it.
Last choice would be using a punch to close the whole.
Neither of the three options should be done by a total novice. I think the Venus 188 might have a fitting bridge too.

(I see nickrelsilver already answered, I write just too slow ;) )

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jasonphares New Member

jasonphares

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thanks for the quick response. this is my watch but I aim to get it back to a a professional condition I can source a new barrel bridge from cousins but not sure if the finish will be the same or if it comes prefixed with jewels, as cousins don't have an image on there site. anyone able to confirm or will I need to ring them in the week?

nickelsilver Distinguished Member

nickelsilver

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Closing the hole will work fine, really no need for more than that. The is really no force on the eccentric, it is just a positioner.

We were taught in school to poke the tapered end of an eccentric into beeswax before installing, and it works well for a smooth action and to keep the eccentric from galling with the bridge.

rodabod Distinguished Member

rodabod

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Another reversible bodge, is to use a weak thread lock and then break the thread lock after it has cured which will leave a skin inside the hole. 
 

 

jasonphares New Member

jasonphares

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thanks for all the advise fingers crossed I can get the adjustment sorted as it was way out when I got the watch and the chrono is locking up the watch movement when its engaged

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