BFG 866 - Balance Help!

[Robbie010]

I had great success today stripping, cleaning and rebuilding a Baumgartner BFG 866.

However, when cleaning the balance, the spring somehow separated from the bridge....... I couldn’t work out how so attempted to simply bend the small pin that holds the spring in place and managed to snap it clean off 

I can see the parts a readily available on cousins so I can buy a new balance bridge, however, can someone tell me the correct way of re-installing the balance wheel/spring without having to bend the little pin?

 

[jdm]

53 minutes ago, Robbie010 said:

However, when cleaning the balance, the spring somehow separated from the bridge....... I couldn’t work out how so attempted to simply bend the small pin that holds the spring in place and managed to snap it clean off 

What you circled is called regulator (index), it doesn't hold or guide the hairsping but just regulate the rate by changing its effective length. This regulator has one curb pin which faces another part called boot, which can be rotated to ease the hairsping in or out.

Incidentally, the pin that actually keeps the hairspring attached to the balance cock is still there, wedged between the end stud and the hairspring.
 

The last observation is that unless you know for sure that the part can take it, never try to bend or otherwise force watch parts. A breakage is the usual result.

  

[Robbie010]

10 minutes ago, jdm said:

What you circled is called regulator, it doesn't hold the hairsping but just regulate the rate by changing its effective length. This regulator has one curb pin which faces another part called boot, which can be rotated to ease the hairsping in or out.

Incidentally, the pin that actually keeps the hairspring attached to the balance cock is still there, wedged between the end stud and the hairspring.
 

The last observation is that unless you know for sure that the part can take it, never try to bend or otherwise force watch parts. A breakage is the usual result.

  

Sorry, poor explanation. I found this picture from a previous post that better explains the issue. The small pin circled in red has snapped off. 

As you can see in this image, the pin seems to act as a guide for the spring so if I buy a new bridge (with the pin and boot in place), how do I refit the spring / balance wheel without bending this pin?

[jdm]

43 minutes ago, Robbie010 said:

how do I refit the spring / balance wheel without bending this pin?

Please read again my previous answer. The points that fully answer your question are in boldface.

[Robbie010]

8 minutes ago, jdm said:

Please read again my answer above. The points that fully answer your question are in boldface.

Perfect!

Thank you very much. 

[Nucejoe]

To get the hairspring in , you don't bend the pin, but rotate the boot.

Boot has a slot for screwdriver blade.

[canthus]

You can get these parts from Cousins UK

https://www.cousinsuk.com/category/hairspring-collets-pins-studs-boots

 

 

[jdm]

7 minutes ago, canthus said:

You can get these parts from Cousins UK

Which is good, although in my opinion replacing a curb bit is delicate work which can be beyond a beginner. 

Also worth to note, if one orders a balance cock, will not receive these parts, which are instead in the regulator index assembly.