Fig. 8
When the collet is turned to replace the spring in beat, the stud will be in its original location on the line "B."
This will cause the pinning point at collet to be shifted from "A" to "B" and bring it that much nearer to the horizontal line "C."
This alteration has the same effect as that of letting out the spring at the collet or of moving the stud forward on the over coil, with the advantage of eliminating any change in the mean time.
It should be definitely understood that the objective in making the above alterations and as illustrated with the aid of the following cuts, is the relation of the pinning point at collet to the pinning point at stud, and that the change in length of the spring has no bearing on the matter whatever as far as the position rate is concerned.
[31.]Even Coil Hairsprings Very Incorrect for Some Models.
It is often supposed that hairsprings having exactly even coils are correct for close position and isochronal rating. Such springs do approximate the nearest correct relation in more instances than any other relation. They are precisely correct for very few models, however, and are very incorrect for many models, as will be seen through study of the following cuts showing the various points of attachment and the different results obtainable in each.
[32.]How to Find the Correct Collet Pinning Point for Any Watch.
A very simple method of locating the proper point of attachment of the spring to collet is to face the train side of the movement and hold the balance stationary with a small twig, and with the pallet fork just midway between the two bankings.