Date change mechanism question

# Thread: Date change mechanism question

1. ## Date change mechanism question

So if my date changes at 1am and say it just turned Sept 3rd. I turn the hands back to say 12:30 am, the date should still show 3rd, but what does the watch actually think it is? What if I turned it back to say 10pm, what should the watch think it is?

2. ## Re: Date change mechanism question

It won't go backwards. But if you see/hear a click, it will advance again at 1am if you go far enough back.

3. ## Re: Date change mechanism question

So if I want to change dates by turning the time, I can change the date by turning back ~4hrs and turning forward again +4 hr instead of turning forward 12 hrs?

4.

5. ## Re: Date change mechanism question

Originally Posted by ttup
So if I want to change dates by turning the time, I can change the date by turning back ~4hrs and turning forward again +4 hr instead of turning forward 12 hrs?
Yes. That's how a lot of us do it on our vintage watches that don't have quickset date complications.

6. ## Re: Date change mechanism question

Watches do not think... They just run down a spring (mainspring) in a regulated manner and show the result on a time scale.

Regarding the date change mechanism, it depends on the movement. To change the date, some movements use a cam driven by a spring. Loading the spring from the clockwork takes about 3 hours. Immediately after the date has changed, if you turn the watch back with about 30min as you suggested, it will not change the date again for 24h (it will still show 3rd). If you turn the watch back with about 3 hours (at 10pm), it will immediately start loading the spring again and within 3 hours (at 1am) the date will change.

This is just an example. Some few high end movements will change the date back to 2nd when you set back to 10pm.

7. ## Re: Date change mechanism question

If it is determined by just that period, then how does the watch determine if it is am or pm?

8. ## Re: Date change mechanism question

Think circle...12 Am/Pm,top 1st time around noon(am), 2nd time after top (12PM) You set the watch as am/pm...If you set it wrong
it will indicate wrong and change at noon.

9. ## Re: Date change mechanism question

Originally Posted by ttup
If it is determined by just that period, then how does the watch determine if it is am or pm?
The watch movement does two things. It rotates the hands so that they complete two 12 hour cycles every 24 hours. It also advances the day and date wheels at the end of one of those 12 hour cycles. You as the watch owner have to advance the hands until the day and date click over as they will at midnight. Then you can set the hands to your local time and the watch will keep time and advance the day and date at midnight.