Editing Engine turning

{{distinguish|swarf}}
{{More citations needed|date=February 2014}}
[[File:Spirit of St. Louis - Motor.jpg|right|thumb|[[Charles Lindbergh]]'s famous aircraft, the ''[[Spirit of St. Louis]]''. The ''{{Lang|fr|[[perlée]]}}'' pattern on the metal panels is one type of engine turning.]]
'''Engine turning''' is a form of [[ornamental turning]]. The finishing technique may use lathes or engines to produce a pattern. [[Aluminium]] is often the metal chosen to decorate. The technique has been used in various industries, including aircraft and document verification.

== Description ==
Engine turning is a form of ornamental turning.<ref name=":0">{{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}}</ref> The technique geometrically applies a single-point cutting tool to produce a decorative metal surface finish pattern.<ref name=":0" /><ref name=":1">{{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}}</ref>

Traditionally, engine turning referred to [[Guilloché]] engraving.<ref name=":2">{{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}}</ref> 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 [[geometry|geometric]] pattern of overlapping circles abraded onto the surface.<ref name=":2" />

=== Equipment ===
[[Guilloché]] engine turning may be done with various machines, including [[Rose engine lathe|rose engines]], [[Straight line engine turning|straight-line engines]], [[Brocade|brocade engines]], and [[Ornamental turning|ornamental turning lathes]].<ref name=":0" /><ref name=":1" /> Perlage uses an abrasive rotating disk or [[dowel]].<ref name=":0" />

=== Material ===
[[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 [[Manufacturing|machined]] to produce intricate repetitive [[pattern]]s that offer reflective interest and fine detail.<ref name=":0" /><ref>{{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}}</ref><ref name=":2" />

==Uses==
{{Unreferenced section|date=December 2023}}

===Aircraft===
[[File:Fokker EII WNr 257.jpg|thumb|A [[Fokker E.II]] 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|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}}

===Automobiles===
[[File:1940 Buick Super Convertible Coupe.jpg|right|thumb|A 1940 [[Buick Super]] 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 cover]]s, which are right on top of the engine, were also decorated with perlage engine turning. Similarly, [[dashboard]]s or the instrument panel of the same were often perlaged. [[Custom car|Customizers]] also would similarly decorate their vehicles with perlage engine-turned panels.

===Documents===
Engravings produced by engine turning are often incorporated into the design of [[bank note]]s, and other high-value [[document]]s, to make [[counterfeit]]ing difficult. The resulting graphics are called [[guilloché]]s.

===Firearms===
[[File:Openboltcropped.jpg|thumb|A bolt action rifle with the bolt position open, and jewelling detail on the bolt surface.]]
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.

=== Watchmaking ===
Guilloché and perlage are traditional techniques used in have been used in the [[watch-making]].<ref name=":0" />

==See also==
* [[Guilloché]]
* {{Lang|fr|[[Perlée]]}}
* [[Rose engine lathe]]

==References==
{{Reflist}}

==External links==
{{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]]