BFG 866 running fast

[Robbie010]

I’ve put my BFG 866 movement back together today, give it a wind and set it going. Using the stop watch on my phone, the watch is running around 10 seconds fast over 60 seconds. 

I’ve tried regulating the watch but it does not seem to make much difference, I got it down to about 6 seconds over 60 but if I turn the regulator any closer to the H/S pin than shown in the image the balance just stops. 

The other thing I notice is that the spring doesn’t seem to sit right, it seems bunched up on one side  

I’m a little stumped here.... any thoughts?

Edited January 20, 2021 by Robbie010

[watchweasol]

Would appear you have a malformed coil (terminal Curve)     as you move the regulator it is bearing on the balance spring pushing it to the side. The regulator should be able to move from fast to slow without mechanically moving the balance spring as it should sit centrally between the regulator pins and only touch the inner and outer pins whilst in action effectivly shortening the spring or lengthening it according to its  position. the attachment  will give you a pictorial walk through of the action.     cheers

204847356_WatchTheoryEscape-Regulator (1).pdf

[handwound]

Just as @watchweasol said the hairspring seems to be out of it's original shape. you can observe that the coils on the left side are closer to each other than on the right side. It can have different reasons:

1. the hairspring is bent. Take the balance out and check if you can spot any kinks in the hairspring. it is possible to manipulate it to get these out, but it's very difficult. 

2. the hairspring is magnetized causing the coils to stick together. Try to demagnetize it. A cheap chinese demagnetizer will to the job.

3. the hairspring isn't clean. If there is oil or some other fluid on it, it can cause the coils to stick together as well. Put the balance complete into Bergeon one dip, benzine or lighter fluid and dry it using an air blower. After that it should be clean.