Part 11 (1/2)
Investigation proved that the motion dropped off considerably after a few hours run and that the mainspring was too weak for this grade of watch. A proper mainspring was fitted which in turn corrected the motion, but the next test in positions proved that there was still a variation of eighteen seconds as per fourth column Fig. 24.
Fig. 24
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No. _10504112_ Make _Waltham_
+--------+-----+-----+-----+-----+-----+-----+-----+
D U
0
0
- 2
- 2
- 1
- 1
P
+--------+-----+-----+-----+-----+-----+-----+
D D
0
0
- 5
- 3
- 1
0
+--------+-----+-----+-----+-----+-----+-----+
P U
+14
+14
-21
-16
- 4
- 3
+--------+-----+-----+-----+-----+-----+-----+
P R
+ 4
-10
-19
+ 2
- 5
- 1
+--------+-----+-----+-----+-----+-----+-----+
P L
+16
+12
-25
- 6
- 3
+ 2
+--------+-----+-----+-----+-----+-----+-----+-----+ 24 18 5
The balance and spring were removed and considerable poise trouble was discovered. The trouble was at different points of the balance and no one location seemed to be heavy at all times. The balance pivots were carefully gauged with a metric micrometer and found to be out of round, or to be exact, more oval in form than cylindrical. A new staff with round pivots was fitted, after which the balance was easily poised and the next test showed a variation of five seconds as per sixth column Fig. 24. The total time required for making the examination and alterations was about one hour.
70. _Example No. 8._
Vacheron and Constantin. No. 272,854, Open Face, 21 Jewels.
Repairs made. New balance staff, hole jewel, cap jewel, gla.s.s, and cleaned.
The first test after making the repairs showed a variation of twelve seconds as per second column Fig. 25.
It will be observed that the rates in the horizontal positions are on the fast side and those in the vertical positions are on the slow side. In this instance the hairspring developed to the left from the collet similar to the ill.u.s.tration shown in Fig. 10, page 45.
Fig. 25
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No. _272854_ Make _V. & C._
+--------+-----+-----+-----+-----+-----+-----+-----+
D U
+ 2
+ 2
- 4
- 4
P
+--------+-----+-----+-----+-----+-----+-----+
D D
+ 5
+ 3
- 8
- 4
+--------+-----+-----+-----+-----+-----+-----+
P U
- 1
- 6
-14
- 6
+--------+-----+-----+-----+-----+-----+-----+
P R
- 8
- 7
-21
- 7
+--------+-----+-----+-----+-----+-----+-----+
P L
-17
- 9
-25
- 4
+--------+-----+-----+-----+-----+-----+-----+-----+ 12 3
Investigation found the escapement, regulator pins and pinning point satisfactory; the motion was one and one-fourth turn in the vertical positions when fully wound and only a trifle less when partially let down. In the flat positions, however, the motion was very little better than in the vertical, which indicated either pivot or end stone trouble as under normal conditions the flat motion would be about one-fourth turn greater than that of the vertical.
Inspection of the end stones proved that they were satisfactory but the ends of the balance pivots were found to be somewhat flat and not perfectly polished.
The ends of the pivots were slightly rounded and highly polished, the jewels and end stones cleaned and reoiled and the balance replaced, after which the motion in the flat positions was one and one-half turn with the mainspring fully wound and only slightly less when partially let down.
The motion in the vertical positions was also slightly improved and the next test in position showed a variation of three seconds as per fourth column Fig. 25.
Time required for making the above alteration was about one-half hour.
In the study of this example it should be clearly understood that when the ends of balance pivots are flat, burred or not well polished, or when the end stones are dry or dirty the motion in the horizontal positions will be shorter than normal and this will always cause the rate to be faster than it should be. Acceleration of the motion in such instances by means of refinis.h.i.+ng the pivot ends or by cleaning and reoiling the jewels and end stones will always produce a slower rate through causing a longer arc of motion.
This point is covered in Chapter XI, No. 47.
71. _Example No. 9._
E. Howard. No. 1,116,735. Open Face, 23 Jewels.
Repairs made. New balance staff; hole jewel; mainspring and cleaned.
The first test in positions showed a variation of eleven seconds. The rate in all positions was fast with the exception of the dial down rate, which was slow. See Fig. 26.
At first glance it might appear that by causing a faster rate of six or seven seconds in the dial down position the watch would have a very good rate. This, however, would not be consistent unless the rate was due to the exception referred to in Chapter XI, No. 50.
Examination of the motion in the horizontal positions proved that it was about one fourth turn better in the dial down position than it was in the dial up position which rate compared very closely with the vertical positions. It was therefore evident that the dial up rate was not true and investigation found the oil in the upper jewel had become thickened by the entrance of dirt which caused the short motion and fast rate when the balance was running on this end stone.
Fig. 26
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No. _1116735_ Make _E. Howard_