What is a datum feature?

What is a datum feature?

• A. A surface, axis, or point used to establish a datum.
• B. An example of a measurement error.
• C. A material specification.
• D. A tolerance line on the drawing.

Answer: (A)

A datum feature is the physical feature on a part that is used to establish the datum reference frame for GD&T. This means it can be a surface, an axis, or a point on the part that provides the basis from which the part’s form, orientation, and location are measured. By selecting actual features like a machined surface or a cylindrical bore axis, you create Datum A, Datum B, Datum C, etc., which then define how other features are evaluated relative to that frame. The other options describe measurement errors, material specifications, or a drawing line for tolerances, none of which establish the reference frame used in GD&T.

A datum feature is the physical feature on a part that is used to establish the datum reference frame for GD&T. This means it can be a surface, an axis, or a point on the part that provides the basis from which the part’s form, orientation, and location are measured. By selecting actual features like a machined surface or a cylindrical bore axis, you create Datum A, Datum B, Datum C, etc., which then define how other features are evaluated relative to that frame. The other options describe measurement errors, material specifications, or a drawing line for tolerances, none of which establish the reference frame used in GD&T.