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Last month’s Tip shows how using profile of a surface can increase allowable tolerance without affecting the function of a part. The original drawing used a size dimension and tolerance plus total runout to control the 18 teeth on the Cutter Ring. Making the size dimension basic and using profile of a surface allows both size and location to be inspected at the same time.
Many people believe profile is difficult to measure. In this example, the profile tolerance is as easy to measure as a runout tolerance. The only difference between profile of a surface and total runout in this case is that the inspector must zero the indicator at the basic location from the simulated datum axis.
This tip is in accordance with ASME Y14.5M-1994.
This tip was originally released in October 2001.