Bidirectional rotor: what a QC video shows and what it does not prove

Watches Movements & Tech
1

With display casebacks everyone looks at the rotor… and then makes up conclusions. This thread limits what can be said about a bidirectional rotor in a short video. Basics: glossary, hand-wound or automatic, arrival check.

[[PHOTO: esquema de un rotor visto por el fondello con flechas en ambos sentidos de giro]]

Editorial summary, not independently verified.

2

In practice:

  1. Ask for a 5–8 second video of the caseback while the wrist is turned slowly in both directions.
  2. Bidirectional: the rotor should wind (or at least drag in a mechanically sensible way) in both directions, depending on the design.
  3. A still photo only shows the rotor decoration, not the winding direction.
3

Newbie question: if the rotor “spins” freely without engaging, is it already broken?

4

Don’t diagnose it from a blurry clip. It may be the angle, normal play at low wind, or simply that the ratchet isn’t visible. Ask for another video with more light and the case resting on the table while it is rocked only slightly. That belongs to the arrival check, not to a JPG.

5

What the rotor video does not prove:

  • exact hours of power reserve (for the dedicated indicator see power reserve)
  • exact calibre identity
  • timing accuracy
  • water resistance

[[PHOTO: storyboard de tres fotogramas — rotor a la izquierda, al centro, a la derecha en un balanceo]]

6

Do you need to name the calibre if the rotor “looks good”?

7

No. Describe finishing and behaviour in both directions. Naming the calibre takes more than a pretty clip — see also manual vs automatic.

8

Summary:

  1. Short caseback video rocking in both directions.
  2. Photo = cosmetics; video = approximate behaviour.
  3. Don’t infer reserve, calibre or WR from the rotor.
  4. Doubtful clip → repeat with better light, don’t speculate.
  5. Glossary and arrival check remain the basis.

Editorial summary, not independently verified.

9

Perfect — from now on I’ll ask for the 8-second clip, not just the caseback photo.