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Categories of GD&T Symbols
Per Y14.5-2009 & Y14.5M-1994

Per Y14.5-2018

Tolerances of Form

GD&T Symbol - Circularity

Circularity

Describes the condition on a surface of revolution (cylinder, cone, sphere) where all points of the surface intersected by any plane.

GD&T Symbol - Cylindricity

Cylindricity

Describes a condition of a surface of revolution in which all points of a surface are equidistant from a common axis.

GD&T Symbol - Flatness

Flatness

Is the condition of a surface having all elements in one plane.

GD&T Symbol - Straightness

Straightness

A condition where an element of a surface or an axis is a straight line.

Tolerances of Orientation

GD&T Symbol - Angularity

Angularity

Is the condition of a surface, axis, or centerplane, which is at a specified angle from a datum plane or axis.

GD&T Symbol - Parallelism

Parallelism

Is the condition of a surface, line, or axis, which is equidistant at all points from a datum plane or axis.

GD&T Symbol - Perpendicularity

Perpendicularity

Is the condition of a surface, axis, or line, which is 90 deg. From a datum plane or a datum axis.

Tolerances of Location

GD&T Symbol - Position

Position

Defines a zone within which the axis or center plane of a feature is permitted to vary from true (theoretically exact) position.

GD&T Symbol - Symmetry

Symmetry

Is a condition in which a feature (or features) is symmetrically disposed about the center plane of a datum feature. No longer available in the 2018 standard.

GD&T Symbol - Concentricity

Concentricity

Describes a condition in which two or more features , in any combination, have a common axis. No longer available in the 2018 standard.

Tolerances of Profile

GD&T Symbol - Profile of a Line

Profile of a Line

Is the condition permitting a uniform amount of profile variation, ether unilaterally or bilaterally, along a line element of a feature.

GD&T Symbol - Profile of a Surface

Profile of a Surface

Is the condition permitting a uniform amount of profile variation, ether unilaterally or bilaterally, on a surface.

Tolerances of Runout

GD&T Symbol - Runout

Runout

Is the composite deviation from the desired form of a part surface of revolution through on full rotation (360 deg) of the part on a datum axis.

GD&T Symbol - Total Runout

Total Runout

The simultaneous composite control of all elements of a surface at all circular and profile measuring positions as the part is rotated through 360.

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