Temperature on accuracy

[Ck8]

There have been many posts on accuracy, how the watch is worn, the positioning at night time on self regulating, the power reserve it has, etc.....

But how much does the climate and temperature affect on accuracy? Certainly Rolex catered for that with the expandable bracelet.

For example in the UK the difference between winter and summer temperatures can be 35c. OK given that you might not wear your watch outside all the time the temperature difference indoors between summer and winter can be 10c. How much would that difference affect the accuracy?
Has anyone notice a difference in their watch with temperature change?

[timeisfathaoftruth]

I think that mechanical movements would tend to run faster in colder weather and slower in warmer temperatures...But I think that they do something with the movement to minimize the above. I bet JJ knows the "accurate" answer!

[snow_rocks]

COSC does 3 temps, 5 positions for 15 days to test for mean accuracy of -4 to +6 secs a day.

[Ck8]

Originally Posted by snow_rocks

COSC does 3 temps, 5 positions for 15 days to test for mean accuracy of -4 to +6 secs a day.

Yes, but does temperature influence the time keeping. For instance in summer it runs fast and winter runs slow but both can be within COSC?

[snow_rocks]

Originally Posted by Ck8

Yes, but does temperature influence the time keeping. For instance in summer it runs fast and winter runs slow but both can be within COSC?

Temperature is not the only factor determining accuracy of a mechanical watch. If that were the only factor, other materials are available to make a watch case that would better insulate the movement, providing for consistent timekeeping.

If a watch is to be worn in extreme cold temps., I would suspect that the watch would be under the sleeve of the proper outer layer of clothing.

[Tools]

Originally Posted by Ck8

Yes, but does temperature influence the time keeping. For instance in summer it runs fast and winter runs slow but both can be within COSC?

Yes, temperature does have an affect.. In cold weather, the hairspring contracts, and in warm weather the hairspring expands..

This change in the hairspring actually changes it's amplitude (amount of swing back and forth)..

Hairsprings are made with metal combinations bonded together today that inhibit this to a large degree and the changes are very hard to measure in a modern mechanical watch.

Extreme cold will affect the viscosity of the oils too, slowing the movement down, although modern synthetics are better at coping with this..

There is a story around about the "thinner" oils used in the watches used to scale Mt. Everest because of the cold weather to be encountered there.

[padi56]

Originally Posted by Ck8

There have been many posts on accuracy, how the watch is worn, the positioning at night time on self regulating, the power reserve it has, etc.....

But how much does the climate and temperature affect on accuracy? Certainly Rolex catered for that with the expandable bracelet.

For example in the UK the difference between winter and summer temperatures can be 35c. OK given that you might not wear your watch outside all the time the temperature difference indoors between summer and winter can be 10c. How much would that difference affect the accuracy?
Has anyone notice a difference in their watch with temperature change?

IMHO different temperatures would effect most watches when off wrist. When worn body heat keeps watches at a reasonable constant temperature..But back around 2000 after living around the far east for around 9 months. Then returning back to the UK I did have a slight change in time keeping on a SD that I bought in Singapore.