.

In this regard, what is the difference between runout and concentricity?

While symmetry measured the true midpoint plane of a feature to a datum plane or axis, concentricity measures the derived midpoint axis to a datum axis. Runout is a combination of concentricity and circularity. Runout = Circularity + Concentricity. If a part is perfectly round, the runout will equal the concentricity.

what is concentricity tolerance? In GD&T, concentricity is a complex tolerance used to establish a tolerance zone for the median points of a cylindrical or spherical part feature. Concentricity is generally reserved for high-precision parts, and only when there is a need to control median points.

Similarly, you may ask, are true position and concentricity the same?

While true position is usually controlled to a fixed point in space that forms from coordinate measurements from a datum, concentricity is controlled to the axis derived from an all the median points of a datum surface or feature.

How is runout measured?

Total Runout is measured by fixing the datum features (typically an axis) and rotating the part along the rotational axis. Another method for measuring total runout is to take one gauge held perpendicular to the surface of the part, and slowly move it across the surface of the part axially as the part is rotated.