BFG 866

[Mac]

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 

[rodabod]

Hi, are you referring to the hairspring stud detaching from the balance cock?

I have highlighted this in red. 

[Mac]

Hi,

How do I attach the hairspring to this part that you have highlighted in red? It has a protruding pin...

Many thanks

[clockboy]

The hairspring threads into stud and held via pin. The stud is then with held into the bridge arm via with a screw (see pic )or some are friction fitted.

[oldhippy]

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.

[Mac]

This one has no provision for fixings. When you say friction fitted there is a slot. I think the pin on the other arm is to act as a guide/support?

[rodabod]

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. 

[Mac]

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. 

[oldhippy]

The end of the H/S fits into a stud, which then fits into the balance bridge, it is held by a tiny screw or pinned, or in some cases its held with what looks like some sort of glue.

[oldhippy]

[Mac]

5 minutes ago, oldhippy said:

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? 

[oldhippy]

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.  

[Nucejoe]

Hi, I will start working on the same calib this evening  have a batch of five pieces to rebuild. Will be happy to walk you through till end.

Regards joe

[gina]

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

[Nucejoe]

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

 

 

[gina]

Just now, 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.

 

 

Ah, ok. Thanks!

[gina]

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?

[Nucejoe]

https://www.amazon.com/TEKTON-Needle-Pliers-Smooth-PMN03001/dp/B07CNSHZ1H?ref_=s9_apbd_simh_hd_bw_b2JwU&pf_rd_r=V39QX91W2G0RDMG7AZ2W&pf_rd_p=f777e310-d215-58e3-b0d8-a750fdeda685&pf_rd_s=merchandised-search-10&pf_rd_t=BROWSE&pf_rd_i=553318

Specifics are needle noise and smooth jaw, long nose is better.

Good luck pal.

[gina]

7 minutes ago, Nucejoe said:

https://www.amazon.com/TEKTON-Needle-Pliers-Smooth-PMN03001/dp/B07CNSHZ1H?ref_=s9_apbd_simh_hd_bw_b2JwU&pf_rd_r=V39QX91W2G0RDMG7AZ2W&pf_rd_p=f777e310-d215-58e3-b0d8-a750fdeda685&pf_rd_s=merchandised-search-10&pf_rd_t=BROWSE&pf_rd_i=553318

Specifics are needle noise and smooth jaw, long nose is better.

Good luck pal.

Thank you very much.

[Nucejoe]

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. 

[Nucejoe]

You are welcome. The system will inform me of you future posts/question. Glad to be of any help I can.

[gina]

So great. Thanks again.