32xx movement problem poll and data thread

[saxo3]

Originally Posted by Gab27

From what I am observing, amplitude is higher when the watch is warmer and lower when the watch is colder.

When my 3130 comes off of my wrist when I've been wearing a sweater that covers it and it is very warm, its DU amplitude is generally 305-315 degrees (but less when I am wearing say a t-shirt). Once the watch reaches ambient temp (about 22 degrees), it is more on the order of around 290-295 degrees. If I put it in the fridge and then measure amplitude, it is substantially lower and then progressively increases as the watch comes to room temp.

For the sake of my own curiosity, I wish to know what the cause is here? Is the viscosity of the lubricant used on the balance wheel pivot increasing in colder temps, resulting in greater resistance and not quite as strong of a 'swing'? (and the opposite when warmer?) Does it have to do with expansion/contraction of the materials in different temperatures, such as the hairspring itself? (I would assume this is not the case given the Parachrom Bleu's design to be extremely resistant to temperature variations?)

Interesting questions, hard to answer. It is very difficult to do any quantitative analysis and try to calculate thermal effects inside a highly compact watch movement comprising many individual components with different material properties.

Used materials, masses, dimensions, thermal contacts and anchoring, friction, viscosity of used oils etc. make a quantification (nearly) impossible.

Take the Nb-Zr-O Parachrome spiral. In order to get a rough approximation about the impact of temperature changes, you would need to determine the so-called expansion coefficient for the Niobium-Zirkonium-Oxygen alloy for a dynamic (no static) situation, other physical properties as well, all without knowing the alloy composition, how the spiral was tempered and so on. Hopeless.

For any systematic study one has to be sure that the entire watch has reached a thermal equilibrium, then your only free parameter is this stable temperature, let it be in water, at air or anywhere else.

Just in case you wish to investigate further, which I don't suggest, you would need to measure the watch temperature in thermal equilibrium and obtain a more precise measurement of the amplitudes (305-315 vs. 290-295).

Anyhow, with such high amplitudes I don't expext any changes w.r.t. timekeeping, it questions more how precisely and reproducibly your timegrapher can measure.

Maybe you can join us with your 32xx data?