Engine turning

[1] The technique geometrically applies a single-point cutting tool to produce a decorative metal surface finish pattern.

[3] In the 20th century, it also came to refer to the different process of Perlée (also known as spotting, jewelling, perlage), which is a fine geometric pattern of overlapping circles abraded onto the surface.

The sheet metal parts of the World War I Fokker Eindecker fighters aircraft series, especially around the engine cowl and associated sheet metal, are noted for having a "dragged" form of engine turning entirely covering them.

It is partly surmised to have been a mechanical method to "clad" a duralumin-alloy sheet-metal panel with a layer of pure aluminum, for corrosion protection.

Engravings produced by engine turning are often incorporated into the design of bank notes, and other high-value documents, to make counterfeiting difficult.