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The Encyclopedia of Horology

Component record · Dial & hands

Day Disc

Partially verified

A disc carrying printed day names.

What it does

Displays the day of the week through a dial aperture.

How it works

Driven by the same calendar train as the date and held in place by its own jumper.

Language variants were supplied to different markets.

Evolution

Multi-language discs became a marketing as well as technical feature.

Known variations

  • Single-language disc
  • Bilingual disc

Identification for collectors

  • A language not matching the watch's market may indicate a replacement disc.

Common failure modes

  • Worn printing
  • Bent disc fouling the dial

Diagram

date ring, thirty-one positionsdate aperturedriving wheel and jumper
Schematic: calendar work under the dial. An outline schematic drawn to show the arrangement of the parts discussed here. It is not a dimensioned working drawing and does not depict a particular maker's calibre.

Sources & references

  1. de Carle, D., Practical Watch Repairing
  2. de Carle, D., Watch and Clock Encyclopedia
  3. Daniels, G., Watchmaking

Where sources disagree, the disagreement is stated rather than resolved silently.