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Don’t Let a General Profile Tolerance Control Your Datum Features
(In accordance with Y14.5M-1994 standard)

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Often, when a general tolerance of profile of a surface is used on a drawing, people forget to apply geometric controls to the datum features. On this drawing, for example, if geometric controls were not specified on the datum features, there would be confusion over the amount of tolerance to be applied to these features since they establish the origins of measurement. Y14.5 does not address this issue. Some "experts" think you should get all of the tolerance while others argue that you only get half. To avoid this debate, always apply geometric controls to datum features!

Back to Tips Tip added Dec 2003