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BFG 866

Mac

By Mac
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Mac New Member

Mac

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Hi all,

I’m a new member and new to this ‘hobby’. This site seems to be where it’s happening.

my very first attempt is with a BFG 866 which I have stripped cleaned and rebuilt. Not applied any oils or greases yet as I plan to do this a few times. However... I have noticed that the hairspring has come detached from the ‘cock’ plate? I cannot see nor find how this is reattached... is this broken?

Any guidance is much appreciated. 

Thanks, Marc 

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oldhippy Distinguished Member

oldhippy

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First make sure the H/S is in between the regulator. You thread the H/S into the little hole and pin it. Make sure the watch is in beat. If you didn’t remove the H/S from the balance wheel it should be right.

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rodabod Distinguished Member

rodabod

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For press-fitted (friction fit), you must remove the balance cock and flip it over. The stud hole must be supported underneath as you carefully press the stud into position. This can be carefully pressed with closed tweezers or a medium screwdriver (say 1.0mm or so). It must be pressed to a depth which leaves the hairspring sitting flat once the balance cock is re-fitted. The hairspring must also be positioned between the curb pins (aka index pins) on the regulator arm; this is sometimes formed with one fixed pin and one rotatable “boot” which can be carefully twisted to open and shut. 

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Mac New Member

Mac

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Thank you for a brilliantly detailed explanation however my knowledge is far from yours... when you say stud? The hairspring has no end to it. Just the wire, should this stud be attached? 

I have tried to attach images but I am not able to for some reason. 

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Mac New Member

Mac

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5 minutes ago, oldhippy said:

maxresdefault.jpg

Many thanks for the images.

My BFG866 is much more crude. I looks like the spring has broken from the ‘stud’ which would press into the cock plate. Does this seem likely? 

2BC963C3-028D-4B63-B82E-C3082BD97D53.jpeg

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oldhippy Distinguished Member

oldhippy

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If you remove the pin from your stud, you might find a tiny part of the H/S if so it has broken. I would try to re-pin and see what happens. You will need to set it in beat and regulate. The H/S probably will need to be adjusted so the coils do not touch each other.  

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gina Member

gina

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On 5/13/2018 at 1:28 PM, oldhippy said:

If you remove the pin from your stud, you might find a tiny part of the H/S if so it has broken. I would try to re-pin and see what happens. You will need to set it in beat and regulate. The H/S probably will need to be adjusted so the coils do not touch each other.  

 

Hello, 

I know this is an older post, but if you happen to see this message, can you let me know how to remove the pin from the stud? I am working on the same BFG 866 hairspring and would like to remove the hairspring so I can try to straighten it out. I'm using this as practice.

Thanks ahead for your help!

g

bfg hairspring.jpeg

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gina Member

gina

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1 hour ago, Nucejoe said:

I screw down the cock back on main plate for safer handling. To unpin the hairsprings ,use smooth jaw pliers and pull straight out.

 

 

I just examined the hairspring again. That pin is very tiny - can you recommend the proper pliers? And, once pulled out, is it easy to put back in?

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Nucejoe Distinguished Member

Nucejoe

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Micro pins are easier to loose than putting back. 

Put a dab of grease on screwdriver blade to set the micro pin perpendicular to the flat side of screw driver blade.the grease will keep the pin in place and it won't fall. Aim the stud hole to insert  the sharp end of micro pin in the hole, use a pair of tweezers to drive the pin home. 

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