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A tick with added bars and numbers specifying roughness.
Also known as: Surface roughness callout, Ra marking
The surface texture symbol is a tick-shaped mark whose additions specify how the surface must be finished and how rough it may be. A bar across the tick forbids material removal; a circle requires that none be removed; numbers give the roughness limit.
Specifies the required texture of a surface, drawn as an asymmetric tick with parameters written around it.
Contexts: Technical drawing
Distinguishes three cases by what is added: a plain tick permits any process, a bar requires material removal, and a circle forbids it.
Contexts: Technical drawing
Carries a roughness value, most often the arithmetic mean deviation, which sets a limit rather than a target.
Contexts: Technical drawing
A short line and a longer line meeting at a point to form an uneven tick, with numerals and letters written around it.
The same family of marks specified in more detail.