# 8-Day Clocks Speeding Up Late In Week?



## AVO (Nov 18, 2012)

I have a couple of 8-day clocks that I have a habit of winding every Sunday morning. They run fine for the week, but over Saturday and into Sunday they tend to run much faster. I guess this is to do with the lessening of tension in the mainspring as it nears the unwound state - am I right? I suppose the solution is to give them a few turns in the middle of the week?

The pendulum clock is not affected by this - again, I assume because the pendulum has a fixed period? The only thing that needs is a little seasonal adjustment - actually, I just nudge the minute hand back by a minute every 3 or 4 days - it's a superb timekeeper.

Does the above make sense to you knowledgeable people?


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## tixntox (Jul 17, 2009)

Perhaps a service is in order? :yes:


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## harryblakes7 (Oct 1, 2010)

Well the 8 day clocks you have sound like they have a standard balance wheel platform type escapement. As the power decreases from the mainspring the amplitude of the balance drops so there is less time between swinging 3/4 of a turn in either direction down to swinging half a turn in either direction............. therefore the time when it ticks or impulses is increased and hence it speeds the clock up.......... nothing to really worry about unless it gets really bad due to a weak mainspring.......... that is why some older clocks have a fusee chain drive on the mainspring so it gives an even amount of tension and power to the escapement.........

Pendulum clocks also suffer from this problem........... but it varies with the type of escapement, anchor or deadbeat, usually an "8 day" pendulum clock will run for much longer, hence the apparent drop off in power is not noticed and after 7 days there is still sufficient power there to maintain a good amplitude........... Barometric pressure and temperature variations can also upset pendulum clocks........... hope that helps............


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## AVO (Nov 18, 2012)

Thanks, Harry - very well explained. It also explains why I once forgot to wind my pendulum clock when I went away for a weekend and it was still going after 10 days or more!


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## Will Fly (Apr 10, 2012)

That's a useful explanation, Harry - I also have an old 8-day clock from the 1930s (a French Ballard movement) and is gains appreciably if I let it run without winding after 7 days. Now I know why!


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## Rook (Oct 22, 2013)

You could just wind it on the 6th day instead of the 8th.


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