Waltham Vibrating Hair spring?

[Alex Knepper]

On a waltham 16s 15j what dose a vibrating hair spring look like and do? Thanks Alex

[Alex Knepper]

On a waltham 16s 15j what dose a vibrating hair spring look like and do? Thanks Alex

[Tom McIntyre]

The vibrating hairspring stud was patented by Fogg in 1860 (? I think.)

It consists of a swinging arm attached near the foot of the balance cock that runs forward along side the cock. At the end near the balance pivot is is constrained by a cam and a stud so that the amount of the arm's swing can be controlled. The hairspring is pinned to the end of the arm with a collet. Thus the arm becomes the "vibrating hairspring stud."

The frequency of the balance can be regulated by changing the amount of the gap or swing of the vibrator. The more the swing, the longer the effective length of the hairspring.

It was believed that this arrangement gave the hairspring the same properties of isochronism as a helical hairspring or an overcoil. The same mechanism in principle was used by Dent and others in English watches where the final outer coil of the hairspring was extended back along the cock to a distant pinning point. In the English form you could think of it as a spring detent version while the Fogg version was a pivoted detent version. (no detents involved of course).

I will have some pictures up on my web site soon of the mechanism.

------------------
Tom McIntyre
Tommy the JOAT's Web