Suppose that when a part was measured using the method shown above, the greatest deviation from the set point was 0.015 mm. This measurement was above the set point. In other words there was 0.015 more material on one of the teeth than specified by the basic dimension. This could be reported as a +0.015 since there was more material than the basic goal.

Another method would be to report the greatest profile error as 0.03 (2 X 0.015) since that would be the width of profile of a surface tolerance that would be required in order for the part to be accepted. Using this method is similar to the method used universally to report position errors. When holes, for instance, are measured, the radial deviation is determined and then doubled so that it may be compared to the allowed position tolerance that is usually stated as a diametral tolerance.

There isn’t a standard on how to report profile variation. I recommend that companies prepare a one-page document that explains the method being used to avoid any confusion.