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Inserting a 2 piece mainspring in omega caliber 28.10 bumperwind

Horologist
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I have been sifting through the forums archives to find any tutorials or write-ups on inserting a two part mainspring into its barrel. It is a bumperwind 28.10 movement from the late 1940’s.
The bridle part is separate from the rest of mainspring! I have inserted the first part and it has some embossed dot. I know this part is correct as I recall it to be like this when I removed it. At first I thought it was the one piece mainspring.
Now for the rest of the mainspring I was wondering what next ? Anyone who has done this or has experience with it, I would appreciate your assistance with many thanks
 
JimInOz
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Has the tail of the mainspring got a catch?
(don't know the name, just a bent back bit).

IMG_4045.webp


If it does, I think it would catch on the stud or dot on the slipping bridle. I would insert the bridle part into the barrel first with the stud end in the direction of rotation and then insert the mainspring as normal and hope that the tail catches the stud when you wind it.
 
Horologist
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JimInOz JimInOz
Has the tail of the mainspring got a catch?
(don't know the name, just a bent back bit).

IMG_4045.webp


If it does, I think it would catch on the stud or dot on the slipping bridle. I would insert the bridle part into the barrel first with the stud end in the direction of rotation and then insert the mainspring as normal and hope that the tail catches the stud when you wind it.
Thanks for your effort of also photographing it!! Much appreciated! It is the first I have seen of this kind as iI have never really serviced one like this, especially to the installation!
I tried to use the mainspring tool but it did not work missing it so I feed it in by hand ( know this is against the rules of horology but it is the only way I could get it to latch properly )
I might have to pull it out again asi did not put any breaking grease on barrel wal!
Many thanks again!
 
Archer
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I just use a new automatic mainspring...problem solved.
 
Horologist
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Archer Archer
I just use a new automatic mainspring...problem solved.
thanks for chiming in. I will go with this advice as I am getting nowhere as the mainspring just keeps missing that spot. I have noticed that if you keep removing it for correct adjustment, this compromises the mainspring shape. How they did it in the past is mind baffling!!!

So the new mainspring would be one piece. Out of curiosity, do most of these Omega mainsprings wind in the same direction?? as I noticed that this seemed to be in the opposite direction of most of the ones I have dismantled unless it was installed incorrectly in the first place?
 
JimInOz
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Horologist Horologist
do most of these Omega mainsprings wind in the same direction??
You can easily work out the correct direction by observing the hook on the arbor when the arbor is fitted to the barrel.
 
Horologist
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JimInOz JimInOz
You can easily work out the correct direction by observing the hook on the arbor when the arbor is fitted to the barrel.
Makes sense! I have worked on some Seiko watches that the winding orientation varies even on similar models. Thanks!!!
 
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