GD&T flatness tolerance gage

grabcad

6.4.2 Flatness refers to a surface's characteristic of having all its components in a single plane. 6.4.2.1 Flatness Tolerance, on the other hand, establishes a tolerance zone defined by two parallel planes that the surface must fall within. When specifying flatness tolerance, the feature control frame is attached to a leader pointing at the surface or an extension of it. This is placed in a view where the controlled surface elements are shown via lines. Importantly, the flatness tolerance should be less than the size tolerance when a size dimension is involved with the surface.