When in Doubt, use Runout! - 2018

In our June 1997 Tip, "When in Doubt, Use Runout!", we discussed the difference between concentricity and runout. Concentricity has been removed from the 2018 standard. In previous editions, it was used to control the derived median line for coaxial features. It was frequently misused (in parts A,B,C, & D, all the external features have perfect concentricity with the hole), is difficult to inspect, and other controls usually do the job much better. Per the 2018 standard, the four ways to control coaxiality are: [Y14.5-2018 Para 10.2, 11.2.1.1, 12.4.1(a) & 12.4.2(a)]