Component record · Plates & finishing
Screws
VerifiedThe small threaded fasteners used throughout a movement to secure bridges, springs, jewels, and other components to the plates.
What it does
Hold movement components in precisely located, removable positions, allowing assembly, adjustment and disassembly for service.
How it works
Watch and clock screws are made to extremely small, standardised sizes (with dedicated horological screw gauges, distinct from general engineering standards), threaded, hardened, and often polished or blued as a finishing step.
Screw heads are typically slotted for a fitted screwdriver blade matched to the slot width, since an incorrectly sized blade easily damages ('burrs') the slot or surrounding finish — a frequent, avoidable source of movement damage during unskilled repair.
Some screws (such as regulator index screws or timing screws in a balance) serve an adjustment function via their mass or position rather than purely as a fastener.
Evolution
From simple utilitarian steel screws to precisely finished, blued, and polished screws in fine watchmaking as a marker of quality; standardised horological screw and thread gauges developed as the industry scaled through the 19th–20th centuries.
Known variations
- Plain steel fastening screw
- Blued or polished screw (see Blued Screws)
- Timing screw (balance rim, adjusts poise and moment of inertia)
- Regulator index screw
Identification for collectors
- Burred or chewed screw slots are a reliable sign of previous unskilled or careless repair work
Common failure modes
- Stripped slots from incorrect screwdriver use
- Loosening from vibration if not properly seated
- Rust or corrosion, especially in unblued steel screws
Photographs
Photographs are illustrative examples of the type, not necessarily the exact object described. Verify details against the source file page.
Sources & references
- de Carle, D., Practical Watch Repairing
Where sources disagree, the disagreement is stated rather than resolved silently.