/fa/ - Fashion

>>14232308
Basically, because Powermatic-80 style escapements only have two eccentric weights, and those weights are much closer to the axis of rotation than on a regular free sprung balance, Powermatic-80 style escapements are more limited in the range within which they can be adjusted for timing rate performance, and even more limited in terms of adjusting for positional variation or any imbalance with the balance wheel itself (you'd need at least four weights to be able to properly address balance issues).

These issues *could* present problems in the long term, and particularly when the movements are serviced. That said, a Swatch Group watchmaker would likely just replace the whole escapement if they had a problem. Doubly so as their heavily automatic production makes them cheaper to manufacture than usual, and the skilled labour of a watchmaker to fiddle with trying to adjust an escapement is expensive.

>>14225419
Crossposting educational content:

In order to understand why those Swatch Group escapements don't work the same way as a proper free sprung balance such as those produced by Rolex, Patek, JLC. etc I have to go a little bit into how a free sprung balance works.

Basically, the timing performance of a balance wheel is determined by several factors: How balanced the balance wheel is on its axis, the length of the hairspring, the inertia of the balance wheel, and the geometry of the hairspring.

On a free sprung balance wheel, the length of the spring is fixed, and the geometry of the hairspring is usually as close as possible to an evenly spaced spiral, however, eccentric weights near the rim of the balance wheel in at least 4 locations allow a watchmaker to finely adjust both the balance of the balance wheel, and its inertia, with the balance wheel gaining inertia as the weights are moved further out from the center axis, and vice versa as they are moved closer.

The further out from the center axis these eccentric weights are located, the more adjustment range they provide because a small weight will have a larger effect in changing the inertia of a balance wheel the further away the weight is to start.

Now, once you understand that, you can look at a Powermatic 80 style balance and notice that it only has two adjustable weights, which is intrinsically not enough to adjust for the balance of the balance wheel about its axis of rotation (you'd really need *at least* four), and the eccentric weights are relatively close to the center axis, where moving them has a proportionally much smaller impact on the inertia of the balance wheel. These two factors combined mean that the adjustment range they provide is not enough to adjust the timing behaviour of the escapement, and selective lasering off of parts of the balance wheel are necessary to achieve balance on the axis and basic timing performance.