Cal. 3120 winding efficiency

[Burlington]

Just wondering if anyone has any knowledge about how much physical movement is needed to charge the power reserve to the full 60h..

There has been the odd occasion since having my Diver where the power has run out quite a bit before the full 60h is due when not wearing.

The reserve is holding fully when I hand wind, but it does seem that more than a few hours of wear are needed to keep it full wound over a long weekend for example.

Does the amount of oscillation matter in Bidirectional winding? I am sure I read somewhere once the rotor weight needs to move a certain number of degrees in any one direction before any power can be transferred to the reserve, so easy to imagine this doesn't happen when pinned down at my desk most of the day !

[eal15]

Hi, I’ve been told that hand winding is always better. I’ve found about 40 winds sufficient but I haven’t tested it. I do know for certain tags wearing the watch, any watch is much less efficient for winding. For must it will do just fine to keep it energized for day to day use but “regular” wear won’t keep it fully energized.


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[Rachdanon]

Hi, when I was using it at my desk job previously, it was able to last over the weekend. The amount of oscillation of the rotor matters as much as the amount of turns of the crown, just that the gear ratios are different hence the degrees of rotation needed are different. My guess is per degree rotation, the rotor winds the mainspring more than the crown - but there is still X degrees of rotation of rotor that is needed to fully wind the watch, as much as Y degrees of turns of the crown are needed. Just that Y > X.

[underpar31009]

30 rotations

[Burlington]

Thanks for the input guys - at some point I will get round to actually measuring the power reserve properly after a days 'normal' wear and report back how close to 100% it was when taking off.