Circularity
by GD&T Basics on December 21, 2014.
The circularity symbol is used to describe how close an object should be to a true circle...
Category: Form
Cylindricity
by GD&T Basics on December 18, 2014.
The Cylindricity symbol is used to describe how close an object conforms to a true cylinder...
Straightness
by Tom Geiss on November 6, 2014.
The standard form of straightness is a 2-Dimensional tolerance that is used to ensure that a part is uniform across a surface or feature. Straightness can apply to either a flat feature such as the surface of a block, or it can apply to the surface of a cylinder along the axial direction. It is defined as the variance of the surface within a specified line on that surface.
Flatness
by Tom Geiss on November 3, 2014.
GD&T Flatness is a common symbol that references how flat a surface is regardless of any other datum’s or features. It comes in useful if a feature is to be defined on a drawing that needs to be uniformly flat without tightening any other dimensions on the drawing. The flatness tolerance references two parallel planes (parallel to the surface that it is called out on) that define a zone where the entire reference surface must lie.