Category: Form

GD&T Symbol flatfness

by GD&T Basics on May 18, 2020.

Check out this question brought up about Flatness in our GD&T Fundamentals Course. We get a lot of questions about when flatness can be applied and how datums can be used with this. There are some simple rules in the geometric dimensioning & tolerancing standards about applying flatness to datum features that you can follow,…

by GD&T Basics on December 21, 2014.

GD&T Symbol:  Relative to Datum: No MMC or LMC applicable: No Drawing Callout: Description: The circularity symbol is used to describe how close an object should be to a true circle. Sometimes called roundness, circularity is a 2-Dimensional tolerance that controls the overall form of a circle ensuring it is not too oblong, square, or…

by GD&T Basics on December 18, 2014.

GD&T Symbol: Relative to Datum: No MMC or LMC applicable: No Drawing Callout: Description: The Cylindricity symbol is used to describe how close an object conforms to a true cylinder. Cylindricity is a 3-Dimensional tolerance that controls the overall form of a cylindrical feature to ensure that it is round enough and straight enough along…

by Tommy on November 6, 2014.

Special Note: Straightness actually has two very different functions in GD&T depending on how it is called out. In its normal form or Surface Straightness, is a tolerance that controls the form of a line somewhere on the surface or the feature.  Axis Straightness is a tolerance that controls how much curve is allowed in…

by Tommy 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.