Rules and Practice for Adjusting Watches

by Walter J. Kleinlein

The vertical points of attachment are seldom used, for the reason that the variation between the pendant right and left positions would be very difficult to control within close limits, due to the existence of the natural error. As these positions, together with the pendant up position are the most important of the four vertical positions, they are given preference, and the natural error is placed in the pendant down position where it will be the least detrimental to the performance of the watch.

[34.]The Natural Position Error and Why it Cannot be Eliminated.

Fig. 14

The natural error generally consists of from twelve to fifteen seconds in finely constructed watches, and exists because of the fact that it is impossible to perfectly poise a spiral spring. The location of the heavy point, however, may be shifted by changing the point of attachment at collet as described in No. 33, this Chapter. The nearest approximation of a poised spiral spring is probably attained through L. Lossier's inner terminal curve. Results are not positive, however, and any deviation from the required precision makes the curve valueless. It is possible to obtain perfect adjustment between three vertical quarter positions and the two horizontal positions, but all four quarter positions cannot be perfectly adjusted because the natural error will show up in one of them. Manufacturers of fine watches do not of course presume to supply perfect adjustment in the five positions. Some however, have considerably closer limits of allowance for variation than do others and it is logical to presume that a line of high grade watches having a five position allowance of six seconds from one position to any other would show better results than another line which had even a six position adjustment and an allowance of fifteen seconds from one position to any other.

[35.]Principle of Pinning Point Alterations.

Fig. 15

When an alteration of any pinning point is necessary, the extent and direction of the alteration are determined by the rate of the watch. For instance, if a spring is pinned at the fast point and if a slightly slower pendant up rate is desired, the spring can be broken off at the collet and pinned one-eighth above the horizontal line.

If the rate is to be made slightly faster, the spring can be let out a trifle at the collet, the over coil reformed or the stud moved forward on the over coil so that the collet point of attachment will come slightly below the horizontal line when the spring is placed in beat. The former alteration causes an approach toward the slow point and in making the latter alteration we assume that the fast point is a trifle below the horizontal line on that particular watch. When altering springs from the extreme fast point to the extreme slow point, it is advisable to remove a trifle less of the inner coil than the extreme calculation. This will cause the point of attachment to be slightly above the horizontal line on the slow side and will most always produce the result desired and if it does not, there is still a possibility of further alteration. The same principle applies in making an alteration from the extreme slow to the extreme fast point and in this case the point of attachment to collet may be just a trifle below the horizontal line.