WatchTech

theCROWNprince
53

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Simply a symptom of engineering reality

Gears need to have "play" or freedom (as already stated) between the teeth to compensate for manufacturing tolerances and keep from binding.

Setting the time forward is the simplest and the most accurate way to set hands on a watch.

To compensate for the exact amount of freedom in any give watch movement (they all vary and will continue to "evolve") one needs only measure this amount of "play".

In the Dial Up position

1) Wind the watch fully
2) Hack the watch with the second hand at "60"
3) Set the hour and minute hand exact to the minute in a clockwise direction. 5:10:00
4) Press in the crown (starting the watch) making sure not to "twist" the crown, inadvertently adjusting the minute hand as you press the crown.
5) Wait 60 seconds and then some until the minute hand reaches the next minute mark exactly.
6) Note the position of the second hand. example: 5:11:13

The second hand indicates there is a 13 second "play" in the dial train.

1) Hack the watch with the second hand at "47" or 60-13
2) Set the hour and minute hand exact to the minute in a clockwise direction. 5:12:47
3) Press in the crown (starting the watch) making sure not to "twist" the crown, inadvertently adjusting the minute hand as you press the crown.
54 Wait 60 seconds to verify your findings were correct
5) Repeat as necessary to fine tune your results.


This process eliminates all allowable "play" in the gears by allowing the minute hand time to "catch up" to the second hand until it starts being driven.

 However this does not compensate for the effects of gravity on the hands. When a watch is 12 Up/Stem right the minute hand will fall ahead from 12-6 on the dial with gravity and fall behind from 6 to 12. This is easily seen in a quartz watch with a sweep second hand (assuming the dial is centered)

Keep in mind, dials are not always "printed" accurately depending upon the method used. For instance pad printed dial tend to be oval.
Also, dials may be off center due to shifting of the dial feet (if designed this way). A more accurate dial arrangement is found on ladies Rolex watches or vintage pocket watches (mainly European) where the dial snaps over the perimeter of the movement offering less error laterally but this does not fully eliminate error from rotation.


In my experience the 7750 is typically 15-20 seconds of play due to the offset cannon pinion, Rolex and Patek are typically in the 10 second range with a traditional cannon pinion design.

This is by no means an indicator of quality or reliability just of tolerances and design.


Hope this is helpful.

Jacob

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