Concentricity and Squareness
Concentricity means the condition of having the same center or axis with every surface equidistant from the axis within a tolerance zone expressed as .XXX” FIM (Full Indicator Movement). Examples are shown in Figures 1 and 2.
When a specific concentricity is required for a threaded surface, be sure the concentricity limits take into consideration the tolerance limits of the threads.
Squareness, perpendicularity, flatness, and face runout are used to denote the relationship of a surface to an axis, pitch cylinder or another flat surface. The variations between them fall within the tolerance zone expressed as .XXX” FIM (Full Indicator Movement).
A perpendicularity note is shown in Figure 3.