Cuckoo clock Oddity?

[boiss]

Now that the weather has warmed up a tad About 4 degrees indoors I've noticed that the cuckoo clock has speeded up, gaining a bit more than 1 minute a day. I always thought that pendulums got longer and the clocks slowed down as my French one did.
It has a wooden pendulum with an adjustable large leaf.
Mike

[pwdrive]

Indoors in the UK wood tends to shrink in the winter and expand in the summer.

Lawrence.

[Joe]

True, Boiss, but thickened oil thins when it's warmer.

- Joe

[Skywave]

I always thought that pendulums got longer and the clocks slowed down as my French one did.
Mike

You're confusing cause and effect. A pendulum-timed clock will slow down as a consequence of the pendulum increasing its length, not the 'other way round'.

Al.

Indoors in the UK, wood tends to shrink in the winter and expand in the summer.
Lawrence.

Time for one period of pendulum is proportional to the square root of the pendulum's length (for small angular displacements only). So, if the length of the pendulum has shortened due to shrinkage, the pendulum will complete one cycle of oscillation in less time - so the clock will run faster

Al.

[pwdrive]

I know zilch about clocks, but a wooden shaft can expand and contract in length but by not a lot, its circumference would expand and contract more.

Lawrence.

[Skywave]

I know zilch about clocks . . . .
Lawrence.

Ditto! But I understand the Physics.

Al.

[pwdrive]

As far as I know the pendulum length can be adjusted in a lot of clocks.
Indoors, wood shrinkage and expansion might be different in Spain because of the climate but in the UK it generally expands in the summer, and shrinks in the winter.

Lawrence.

[Refugee]

Wouldn't it be humid with little need for heating in winter and dry in summer?
It would shrink as it dries out in spring.

[boiss]

I understand very well that the effective length of the pendulum controls the beats of the clock. The fact that it has sped up in the warmer environment is what has surprised me. The pendulum (bob) is adjustable and this I would normally move up the shaft about 1/2 mm when it got warmer. Refugee may have something about the humidity, It has been unusually damp since before Christmas. Relative humidity has been around 60-70% but looking at the Hygrometer now it is bang on 40%. The wood looks to be Cedar or something similar. The temperature indoors will probably get up to around 28C and then we will have to use the A/C, anyway until then I'll keep my eye on it and won't adjust it.
cheers
Mike