Clone 7750 problems

[AP1875]

I’ve serviced a few basic movements now with good results so I wanted to move onto a chronograph movement, with the 7750 being the obvious choice.

 

I don’t have the money to buy an ETA 7750 right now so I’m playing around with a clone I bought from another forum. It is clone from a replica Audemars Piguet watch and it has extra gears to move the seconds sub dial to the 12 position.

 

Now, I took it apart ready to follow Lawsons 7750 guide but didn’t realise there were all these extra parts. So instead of moving on to the tutorial I planned to reassemble the extra gears a few times, just so I can remember how to do it.

 

There are 4 extra wheels just to turn the seconds hand, 5 wheels in total.. what could possibly go wrong....

 

Here are the bottom two

 

 

 

 

Then you place a plate on top and those wheels turn the 3 on top with wheel 5 holding the seconds hand

 

 

My issue is wheel 1 is no longer transferring power past wheel two. Once the the plate goes on and I place on wheel 3 it runs for a while then stops, if I place on wheel 4 it stops immediately.

 

The movement is still running when the wheels stop.

 

Would I be right to assume wheel one is slipping on the pinion it’s pressed onto (same way you would fit hands at seconds at 6 position) thus not having enough power to move the other gears?

 

When I removed wheel 1 originally it shot off, now it is very easy to remove. Could it have been glued on? Would applying some glue stop wheel one slipping?

 

I can’t see any damage to the gears or dirt so I’m really struggling to see it being anything else.

 

Any input really appreciated on this my heads getting sore from banging it against the wall....

 

 

 

 

 

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[qhartman]

Probably not glued, but probably tightly friction fit. Look closely at the pinion and wheel, there may be a section that could be crimped to fit tighter, like staking a cannon pinion? I'm also pretty new at this, so apply a lot of salt to this idea!

Some possibly relevant info, but for cannon pinion: http://blog.watchdoctor.biz/2018/02/11/what-is-a-cannon-pinion/

Maybe a similar concept here?

[AP1875]

Thanks for the article interesting read. Couldn’t see any indentations on the pinion though

Here’s the post



And the gear





(Apologies for being out of focus, I need a tripod).

I guess it’s the same as fitting a hand to the sub dial except its operating as a gear.


I’m still thinking a tiny dab of glue but could be completely wrong. This movement probably came out of Chinese factory from things I’ve heard before I wouldn’t be shocked if they use a tiny bit of glue...

If you’ve ever had a loose sub dial hand after removing it, how do you create a secure fit?


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