/fa/ - Fashion

>>13880165
For traditional mechanical watches, positional variance is mostly caused by poor balance poise, changes in pivot friction, and changes in hairspring geometry.

The first is the easiest to address - simply make sure the balance is properly poised (doesn't have any heavy spots or light spots). This is traditionally done with screws in the balance, although eccentric weights could in principle be used. Many watches that are adjusted are adjusted by correcting poor poise.

Changes in pivot friction are harder to deal with. A watch has very different interactions with its pivots when in a horizontal vs vertical position. Thinner, more precise arbors and perfectly machined jewels counter this problem some, but it's difficult to solve.

Hairsprings deform under different gravitational pulls. The biggest effect is found in regulated balances, because the way the hairspring interacts with the regulating pins changes as the watch changes orientation. Moving to a free-sprung balance eliminates this issue (when I was talking to some watchmakers from patek, they said this was the most important reason they use free-sprung balances, where they do). However, even a free-sprung balance will change shape slightly under gravity and thus change its rate.

Note that a double-axis tourbillon does not completely eliminate all these influences. The changed friction through the pivots of the geartrain will impact how much power is delivered to the balance from the mainspring, thus affecting the rate.

Tuning fork watches are also very meaningfully impacted by positional variance. The original accutron had a 5 second delta between positions because of how the natural frequency of the fork changed depending on its orientation. The 2nd-gen ESA9162 developed by Max Hetzel for ESA largely corrected this issue with a more symmetric fork design, though by no means entirely.

>>13730426
"Chronometer" doesn't just mean "runs -4/+6 on the wrist"

>>13702390
a full minute per day is a lot. I believe the 7s26 movement in the skx is rated +40/-20 spd.

A standard benchmark for mechanical watch accuracy is ISO3159, which is tested by COSC in switzerland, among other places. It requires a mean daily rate of +6/-4 across 5 static positions, although it allows significant variations between the positions and makes no particular guarantee about performance on the wrist. Tissot at least has a COSC-certified watch (the powermatic 80 chronometer) available just below $500 gray market.

>>13652504
Your claimed accuracy on the 4r and 9015 remain laughable, I don't care how many watchuseek posts you've read. Still no UHF. I'd take the armida a11 over tiger concepts, or at least as an alternative. Also should have the Le locle as an alternative to the thick-o-date. The Casio popewatch should be there at least; not everyone who wants a cheap watch wants a digital.

>>13615320
>I feel like it would pass the certification again.
Why not test it?

>>13536250
>The ED-E100 movement is accurate to within +/- 2s a month (I've checked).
> Not TC
explain more? That performance would be exceptional bordering on impossible unless restricted to a very regular thermal profile. No matter how good the watch, if they aren't using TC and are trying a standard 32khz xy-cut tuning fork crystal, the temperature response will be about the same.

>>13508898
I'm keeping them at constant temperature for ISO3159 timing testing

>>13470019
Here you go. For the cosmic, D is 0.1spd off Chronometer spec, everything else (except mean rate) is within.