gage systems by jus-rite engineering DESIGNERS AND BUILDERS OF
GAGES AND SPECIAL MACHINES

CERTIFIED TO
 ISO9001:2008

Elkhart, IN.  574-522-9600
 
Geometric Dimensioning and Tolerancing

Geometric dimensioning and tolerancing (GD&T) is used to define the nominal (theoretically perfect) geometry of parts and assemblies, to define the allowable variation in form and possible size of individual features, and to define the allowable variation between features.

Symbol Chart





Angularity - the condition of a surface or axis at a specified angle (other than 90 degrees) from a datum plane or axis. The angle must be basic.

Circularity - a condition of a surface of revolution where (a) for a cylinder of cone, all points of the surface intersected by any plane perpendicular to common axis are equidistant from the axis; (b) for a sphere, all points of the service intersected by any plane passing through a common center are equidistant from the center.

Concentricity - a condition where the axes of all cross-sectional elements of a surface of revolution are common to the axis of a datum feature.

Cylindricity - a condition of the surface of revolution in which all points of the surface are equidistant from a common axis.

Flatness - t he condition of a surface having all elements in one place.

Parallelism - a condition of a surface equidistant at all points from a datum plane. Or an axis equidistant along its length to datum axis.

Perpendicularity - the condition of a surface, median plane, or axis at a right angle to a datum plane or axis.

Position - defines a zone within which the center axis, or center plane, of a feature of size is permitted to vary from true (theoretically exact) position.

Profile of Line - the tolerance zone established by the profile of a line tolerance extending along the length of the considered feature on single elements.

Profile of Surface - the tolerance zone established by the profile of a surface tolerance is three dimensional, extending along the length and width (or circumference) of the considered feature or features.

Runout, Circular - controls singular line elements on the surface of a feature related to a datum(s).

Runout, Total - controls full surface (FIM) variations on the full surface of a feature related to
datum(s).

Straightness - a condition where an element of a surface of an axis is a straight line.