variable accuracy - what factors affect and cause variability?

[Wilson_smyth]

What factors affect movement accuracy?
I have started tracking accuracy over the past few weeks, and one watch in particular has a jagged graph in places, rather than a smooth line showing a gradual departure from the accurate current time.


I generally only wear a watch for a few days at a time, after which it may not be worn for weeks.
If a watch is consistently used, does this potentially assist in it becoming more accurate, or at least give a more predictable linear deviation?

[rfrazier]

Everything, just about. So much so that I find it amazing that so many work so well. Here are some factors.

1. Temperature
2. Gravity (e.g., orientation)
3. Condition of movement
-- structural faults, such as nicks in pivots, ill shaped wheels, and worn bearings
-- oil condition and distribution
-- dirt
4. Magnetic fields
5. Shocks
6. Fit of parts (e.g., an hour hand rubbing something)
7. Pixies (misc / improbable collapse of the wave packet)

Best wishes,
Bob

[LondonNeil]

Go on YouTube and look for Roger smiths lecture to the ny horology society called (something like) designs for a practical watch escapement.

Iirc, temp had a big affect by altering the oil viscosity. Then orientation will also affect it. After that other adverse environmental factors like vibration or shock must have an effect I guess.

[paskinner]

Add the level of power reserve to that list.

[verv]

which wrist its worn on

[Tom-P]

Add the level of power reserve to that list.

Yes, that's the biggest variable I observe in the course of my not very variable life. Accuracy drops a little in watches worn in rotation and therefore sometimes subsisting in a low state of wind.

[walkerwek1958]

Iirc, temp had a big affect by altering the oil viscosity.

Over the normal range of temperatures a watch experiences I can`t see this being significant. I`ve used different viscosities of oil in the parts that will affect the running of a watch and the effect has been relatively small, therefore I don`t see this as significant.