roundness in GD&T
circularity symbol is also called roundness some time.
This symbol is used to describe the required roundness of
Roundness is a condition of a surface or revolution
1. For a cylinder or cone, all points of the surface intersected
by any plane perpendicular to a common axis are equidistant
from that axis.
2. For a sphere, all points of the surface intersected by
a plane passing through a common center are equidistant from
The following example showing the circularity specification
of 0.2 is called out from the control box, it can be simply
measure the roundness of the object, Allowable tolerance is