Collet on Ingersoll Trench Wrist Watch

[Seth]

Hi there to all I hope you are all keeping safe during this terrible pandemic.Anyhow I am seeking some help with a hairspring collet on an Ingersoll Trench Wrist watch.I have 2 of these watches one was purchased as running if you gently shook the watch and the other was a non runner for spares.The runner was stripped cleaned and reassembled and the dial from the non runner was used as this was in almost mint condition.The dial by the way is a paper printed disc stuck onto a brass dial plate.So I now have a good running watch which I just have to regulate and adjust.I then stripped the non runner which had a broken mangled hairspring but fortunately the balance staff and wheel and lever was in good order.What I am trying to find out is how the hairspring is attached to the collet as there is NO TAPER PIN used to secure the spring.On looking at the collet after removing from the balance staff under a microscope there is a groove round the center of the collet and part of the broken hairspring stuck in this groove.Is the spring a friction fit in this groove or is there something else holding the spring in to the groove.Any help or ideas would be gratefully received.I enclose a couple of photos of this collet.Regards to all,Keep safe,Seth. 

[Nucejoe]

Spring is placed in the groove, impacted to close the groove. I imagine you can buy fresh collets at major material houses. Manufacturers normally have dedicated proprietory collet tools which collets one in a jif.