Component record · Case

Case Screws

Verified

Small screws used to secure the movement within the case, and, in some case designs, to hold the case back or bezel closed.

What it does

Fixes the movement firmly and repeatably in position within the case, preventing it from shifting, rotating, or lifting out of alignment with the stem, dial window and crown.

How it works

Case screws commonly bear on a small clamp (a case clamp or movement clamp) that presses against the edge of the movement or movement ring, rather than passing through the plates themselves, so the movement can be secured and released without drilling or threading the plates.

In screw-back or screw-bezel case constructions, larger case screws (or a screwed ring) instead clamp the case back or bezel against the case body, contributing to case rigidity and, in water-resistant designs, to consistent gasket compression.

Correct case-screw tension is a balance: too loose and the movement can shift or rattle; too tight and the movement or case may be stressed or the screw thread stripped.

Evolution

Case-clamp screw fixing has remained a standard, simple solution throughout the history of cased watch movements, alongside alternative fixings such as case snaps for movements without dedicated clamps.

Known variations

Movement clamp and case screw
Screwed case back secured by dedicated case-back screws
Screwed bezel secured by case screws or a screwed retaining ring
Movement clamps ('dogs'): small screwed clamps that bear on the edge of the movement or a casing ring, used instead of case screws in many wristwatches