A take on Breguet hairspring
Illinois Watch from 1920’s
A customer brought in a petite Illinois watch from the 1920s, equipped with an Illinois 3/0s, 17 jewels movement. Although the watch was operational, the timegrapher failed to detect any signal.
The donor
There were many issues with the watch.
It began with a glued dial, which I presume was due to the absence of both grub screws.
Additionally, several jewels were cracked, and the ratchet wheel screw was stripped.
The only solution to get the watch working again was to obtain a donor movement, which I managed to find on eBay.
There remained one significant issue that had not been addressed: the hairspring. The one in the watch was rusty and misshapen. The donor spring was bent oddly, causing the overcoil to touch the spring itself. It bore signs of a previous repair attempt, which evidently had not been successful.
First step:
I prefer to restore the spring to its original shape before reshaping it.
In the video, I "removed" the overcoil and straightened the twists in the spring.
With old springs, there's always a risk of breakage, so it's important to be cautious and bend it slowly but steadily.
The video is speeded up.
Manupilating the hairspring back to its original shape
Reshaping:
With Breguet hairspring there are some “rules” that has to be followed.
The slope from flat to top of the coil should be approximately 30° and the overcoil should start 270° from the stud.
I am using balsa wood as support when bending the spring, but it can also be done directly on your bench matt.
First step is to bend the 30° slope, then turn the spring over, move your tweezers little bit against the stud and bend it back so the overcoil is parallell with rest of the spring
Bending the overcoil
Shaping the overcoil:
The curve must be shaped evenly to ensure that the spring maintains its position when adjusting the regulator.
Shaping the curve
After a good clean..
and some minor adjustment. the hairspring is back in shape
And the proof is in the pudding
Final test
That’s all for this time.
Please feel free to add your comments below and share your thoughts. Your feedback is always appreciated and helps us improve.
Stay tuned for more updates and insights in our next post. Until then, happy watchmaking!
