What is "engine turning"

Engine \En"gine\ ([e^]n"j[i^]n), n. [F. engin skill, machine, engine, L. ingenium natural capacity, invention; in in + the root of gignere to produce. See Genius, and cf. Ingenious, Gin a snare.]

1. Note: (Pronounced, in this sense, [e^]n*j[=e]n".) Natural capacity; ability; skill. [Obs.]

   A man hath sapiences three, Memory, engine, and intellect also.
   --Chaucer.

2. Anything used to effect a purpose; any device or contrivance; a machine; an agent.
   --Shak.

   You see the ways the fisherman doth take To catch the fish; what engines doth he make?
   --Bunyan.

   Their promises, enticements, oaths, tokens, and all these engines of lust.
   --Shak.

3. Any instrument by which any effect is produced; especially, an instrument or machine of war or torture. ``Terrible engines of death.''
   --Sir W. Raleigh.

4. (Mach.) A compound machine by which any physical power is applied to produce a given physical effect.

   Engine driver, one who manages an engine; specifically, the engineer of a locomotive.

   Engine lathe. (Mach.) See under Lathe.

   Engine tool, a machine tool.
   --J. Whitworth.

   Engine turning (Fine Arts), a method of ornamentation by means of a rose engine.

   Note: The term engine is more commonly applied to massive machines, or to those giving power, or which produce some difficult result. Engines, as motors, are distinguished according to the source of power, as steam engine, air engine, electro-magnetic engine; or the purpose on account of which the power is applied, as fire engine, pumping engine, locomotive engine; or some peculiarity of construction or operation, as single-acting or double-acting engine, high-pressure or low-pressure engine, condensing engine, etc.

Engine turning refers to a fine geometric pattern that can be inscribed onto metal as a finish. Aluminium is often the metal chosen but any metal can be finely machined to produce intricate repetitive patterns that offer reflective interest and fine detail.

Perhaps the most recognizable example of engine turning is the engine cowling (nose) of Charles Lindbergh's aircraft, the Spirit of St. Louis. In the 1920s and 1930s, automobile parts such as valve covers, which are right on top of the engine, were also engine-turned. Similarly, dashboards or the instrument panel of the same were often engine-turned. Customizers also would decorate their vehicles with engine-turned panels similarly. Recently, one firm engine-turns the faces of its automobile instruments for customizers who don't want to have to turn a panel themselves.

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

The sheet metal parts of the World War I Fokker Eindecker fighter aircraft series, especially around the engine cowl and associated sheetmetal, 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, and is partly surmised to have been a mechanical method to "clad" a duralumin sheet metal panel with pure aluminum with a disc of pure aluminum in the tool, for corrosion protection.