Component record · Case
Case Screws
VerifiedSmall 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
Identification for collectors
- Small screws visible at the edge of the movement bearing on a clamp, or around the perimeter of a screwed case back or bezel
Common failure modes
- Stripped screw threads from repeated servicing
- Lost case screws allowing the movement to shift within the case
- Corroded or seized case-back screws resisting removal without damage
Related photographs
No confidently matched photograph of this subject has been found yet. These photographs show a closely related record, and are not examples of the type described on this page.
Sources & references
- de Carle, D., Practical Watch Repairing
Where sources disagree, the disagreement is stated rather than resolved silently.