Finely adjusted watches will always be found to have springs as nearly perfectly centered as it is possible for expert workmen to get them and it is quite interesting and instructive to observe the vibration of a perfect spring by any one interested in the work.
Some watchmakers center the spring on the balance cock before it is staked on the balance and very good results can be obtained in this way. The balance cock is placed on the bench in the inverted position which makes it easy to locate the point or curve requiring alteration.
59. _Correcting Pendant Up Variation Through Pinning Point Alterations._
Should most careful investigation of the condition of the watch indicate that the Motion, Regulator Pins, Poise of Balance and Centering of the Hairspring as well as the general condition of the watch are satisfactory and the rating show that there is still considerable variation between the horizontal positions and the pendant up position there is still one source through which positive correction may be obtained.
This refers to the relative positions of the collet and stud pinning points which is defined with explanatory cuts and formula in Chapter VIII.
60. _Percentage of Watches Requiring Correction of Position Rates._
In constructing this chapter and the preceding one it has been preferred to go into detail for the purpose of defining the possible corrections and alterations, together with the results to be expected. Not every watch demanding position correction would require the extent of investigation and possible alteration that is pointed out and in most instances the direct cause will be disclosed with very little investigation. In fact, the experienced adjuster can tell almost immediately where to look for trouble by merely observing the position rate as entered on the card.
It should also be clearly understood by the student that when the repairing and cleaning of high grade watches is done by one who understands the details of adjusting, there will be only a very small proportion of the watches requiring position corrections. As a rule among experienced adjusters there will be about seventy per cent of the watches that will have very close rates. If, therefore, one hundred watches are put in order and tested in positions there should be seventy that do not require any correction, while about thirty will require either minor or major alteration. The time required for making alterations on this thirty per cent of the watches will be offset by a smaller percentage of unsatisfactory returns and a better reputation for doing good work.