Part 10 (1/2)
The first position test showed a variation of twelve seconds slow pendant up as per second column Fig. 19.
Fig. 19
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No. _1438676_ Make _Hampden
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Investigation found all points such as balance true, hairspring true, level and circle and the regulator pins reasonably satisfactory. The motion, however, was not as good as it should have been when the spring was nearly wound up. It was let down to where it would ordinarily be after about twenty-hours run and found to have barely one turn pendant up and a trifle over one turn in the flat positions.
This proved that the motion was not satisfactory for a watch that had just been put in order and all pivots were examined for close end or side shake; they were found to be satisfactory and the mainspring was removed for examination and found to be somewhat set and about 0.01 mm. thinner than those generally used for this grade watch. A new mainspring was fitted and the motion was improved by about one-fourth of a turn and the next position test showed a variation of two seconds as per fourth column Fig. 19. The time consumed in examination and changing the mainspring was about twenty-five minutes.
The three position limit of variation allowed by most manufacturers and railroad inspectors is seven seconds from one position to any other. Records of thousands of watches on which the work has been carefully done in putting the watches in order, show that about seventy per cent of the watches will rate within five seconds in the three positions without making alterations and that only ten per cent will be close to the limit of seven seconds, while about twenty per cent will require alterations such as shown in the four examples above. (See Chapter XII, No. 60.)
One or two more examples might be introduced to show variations and corrections between dial up and dial down; this feature has been pretty well covered however in Chapter XI, and five position example No. 9 also shows a variation of the horizontal rates with correction.
CHAPTER XIV
CONCRETE EXAMPLES SHOWING DEFINITE FIVE POSITION ALTERATIONS AND LABOR UTILIZED
66. _What Five Position Adjusting Consists of--Detailed Allowances._
Five position adjusting consists of a further refinement of the condition of the watch. The fact that a very close rate is shown in the first three positions is not an indication that the watch will be an excellent timepiece under all conditions.
In fact there are instances where there may be an excellent three position rate and a further test in the pendant right and left positions may disclose some error that would positively prevent close timing in service. Even under the five position test the limit of allowance must be reasonably close or unfavorable conditions may exist and cause irregularity in timing.
A popular allowance for very fine watches among Swiss and some American manufacturers is six seconds variation for the five positions as an extreme limit, and for medium high grades ten seconds extreme variation is considered a fair allowance. These allowances are graduated, however, and a six seconds extreme allowance watch would have an allowance not exceeding three seconds in the horizontal positions, with two seconds additional in the pendant up position and one second additional in either the pendant right or pendant left positions.
Watches having an extreme allowance of ten seconds may be permitted to have not more than five seconds variation between the two horizontal positions, with two seconds additional for the pendant up position and still three seconds additional in either the pendant right or left positions.
It will be noted that there is considerable difference between six or ten second allowances of this description and straight limits of six or ten seconds.
Some manufacturers have greater limits of allowance, sometimes as great as twenty-five seconds for the five positions, but as a rule the first three positions are required to rate within seven seconds and the difference of eighteen seconds is divided between the right and left positions.
Under limits of this description a watch that would not be tolerated under the six or ten seconds cla.s.s would be considered as good.
Watches having such large allowances, however, and rating close to the limit are hardly justified in being considered as adjusted to five positions. The fact that they are so considered however, is the reason why watchmakers will sometimes fine wide variation in new watches before they have been damaged or mishandled. The following five position examples were selected with the same care as were the three position specimens and will be found to cover a wide field of variation for comparison with rates that the adjuster may desire to correct.
67. _Example No. 5._
Hamilton, No. 248027; Open Face, 21 Jewels.
Repairs made. New balance staff and cleaned. The first test in five positions showed a variation of twenty seconds as per second column Fig. 20. It will be noted that in four of the positions the rate was quite close and that the pendant right position had an extremely fast rate.
A casual investigation indicated that all points relating to the spring, regulator pins and balance were reasonably satisfactory but that there was a slight falling off in motion in the pendant right position. Further investigation of this feature disclosed a slight striking sound when the watch was held to the ear in this position.
The dial was removed and the bankings were closed to drop whereupon it was discovered that the fork was long on the inside, or when the receiving stone was locked on the escape teeth. This prevented the roller jewel from pa.s.sing through the fork freely as it did on the opposite side.
The balance pivots had the limit of allowance for side shake which aided the cause of the roller jewel in striking.
Fig. 20
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No. _248027_ Make _Hamilton_
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