Hairspring Manipulation Advice- Benrus DS 10 Wristalarm AS1475

[AdamT]

Hello!

I am trying to regulate the Benrus DS10 Wristalarm - AS1475 but I am running into an issue that it will swing very quickly from -50s/d to +50s/d with very small changes in position. Looking at the hairspring installed on the balance bridge the hairspring will not sit naturally with in the index post. When the index holder is closed, it looks like it will almost interfere with the hairspring.

I do not have a good reference as to what the hairspring should look like. I understand the part of the hairspring that would interface with the index post should be at a slightly different curve to the rest of the hairspring. I am not sure if the bend that is at the edge of the hairspring should be there or if that should be corrected into a gentle curve to the rest of the hairspring.

My assumption for the next step would be to remove the hairspring from the balance wheel and check to see if the hairspring is concentric to the pivot jewel along the sweep of the regulator. But how do I determine where the curve should end?

Any advice, tips, or tricks would be greatly appreciated!

[nevenbekriev]

OK, I have 'rectified' the hairspring on the image to show how it should look like.

[AdamT]

Thanks for the advice! This is the ending shape that kept the collet in the middle of the pivot throughout the sweep of the adjuster. Ended with a gain of 30-40 amplitude, +15s/d and <1ms BE. Very happy with the result.