Engine turning

Engine turning is a form of ornamental turning.{{cite web |title=Engine Turning vs. Spotting |url=https://www.circuitousroot.com/artifice/machine-shop/surface-finishing/engine-turning-vs-spotting/index.html |website=Circuitous Root}} The technique geometrically applies a single-point cutting tool to produce a decorative metal surface finish pattern.{{Cite web |title=General Descriptions and Basic Sources (for Ornamental Turning and Straight-Line Work) |url=https://www.circuitousroot.com/artifice/machine-shop/ornamental-turning/general/index.html |access-date=2023-12-13 |website=www.circuitousroot.com}}

Traditionally, engine turning referred to Guilloché engraving.{{cite web |last=Warfield |first=Bob |date=18 July 2017 |title=Guilloche, Rose Engines, Jeweling, & Engine Turning for Artistic Machining |url=https://www.cnccookbook.com/guilloche-rose-engines-jeweling-engine-turning-artistic-machining/ |website=CNCCookbook}} In the 20th century, it also came to refer to the different process of {{Lang|fr|Perlée}} (also known as spotting, jewelling, perlage), which is a fine geometric pattern of overlapping circles abraded onto the surface.

Guilloché engine turning may be done with various machines, including rose engines, straight-line engines, brocade engines, and ornamental turning lathes. Perlage uses an abrasive rotating disk or dowel.

Aluminium is often the metal chosen to decorate with jewelling, but any appropriate{{Clarify|reason=What makes a surface appropriate for engine turning?|date=December 2023}} surface can be finely machined to produce intricate repetitive patterns that offer reflective interest and fine detail.{{cite web |title=Eamonn Keogh's Engine Turning Page |url=https://www.cs.ucr.edu/~eamonn/et/et.htm |website=Computer Science and Engineering - University of California, Riverside}}

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File:Fokker EII WNr 257.jpg of late 1915, with "dragged" engine turning on the engine cowl and associated sheet metal.]]

{{Lang|fr|Perlée}}-style engine turning was used on the sheet metal panels of the engine cowling (nose) of Charles Lindbergh's aircraft, the Spirit of St. Louis.

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. The tool creating the "swirls" was repeatedly moved along a short, irregular path each time while pressed against the metal, to create the intricate appearance that was characteristic of the aircraft's sheet-metal parts. 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.{{citation needed|date=October 2022}}

File:1940 Buick Super Convertible Coupe.jpg convertible coupe with a {{Lang|fr|perlée}} pattern on the dashboard panels, used by Buick in 1940 and 1941.]]

In the 1920s and 1930s, automobile parts such as valve covers, which are right on top of the engine, were also decorated with perlage engine turning. Similarly, dashboards or the instrument panel of the same were often perlaged. Customizers also would similarly decorate their vehicles with perlage engine-turned panels.

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

File:Openboltcropped.jpg

Perlage engine turning is also used on various firearm components to prevent corrosion by holding traces of oil and lubricants on the surface, in turn to a polished surface resulting in a smooth operation.

Guilloché and perlage are traditional techniques used in have been used in the watch-making.

• Guilloché
• {{Lang|fr|Perlée}}
• Rose engine lathe

{{Reflist}}

{{Commons category|position=right|Engine turning}}

• [https://www.youtube.com/watch?v=DyLDYD8OdSc Engine turning on YouTube] by The Unemployed Prop Guy

Category:Visual motifs

Category:Corrosion prevention