Movement record · Japan

Miyota 8215

Partially verified

Automatic calibre supplied widely to the trade

Technical specifications

Diameter: Approx. 26 mm
Height: 5.67 mm
Jewels: 21
Frequency: 21,600 vph (3 Hz)
Power reserve: Approx. 40 hours
Winding: Automatic with manual winding
Setting: Pendant set with quick-set date
Escapement: Swiss-style lever
Balance: Monometallic balance
Complications: Date, Centre seconds

Identification features

Unidirectional winding with a characteristic rotor sound
Miyota calibre marking

Known variants

9015 thinner family
Date and no-date variants

Servicing notes

Cleaning, lubrication, mainspring and pivot work belong with a qualified watchmaker working from calibre-specific documentation. Conserve original parts: replacing a worn component with a modern substitute changes the object, and refinishing plates or dials destroys evidence.

General guidance only. Antique movements should be serviced by a qualified watchmaker.

Historical significance

A Japanese equivalent of the Swiss ébauche trade: one calibre sold under a great many brand names, making movement identification essential.

Diagram

Schematic: plate and bridge layout. 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

de Carle, D., Watch and Clock Encyclopedia
Period trade material catalogues and calibre reference compilations (edition-dependent)
Published manufacturer technical documentation where available

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