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Use Profile of a Surface Because it Is Easy to Measure
(In accordance with Y14.5M-1994 standard)

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There is this huge misconception that profile of a surface is hard to measure. If profile is applied to an extremely complex surface, sure, it is a challenge - not because it is profile but because it is a complex surface. Profile of a surface relative to a datum reference frame, when applied to regular features is actually easier to measure than surfaces controlled by plus/minus tolerance since toleranced dimensions do not relate to datums. As with any inspection, you can’t check every point on the surface. Merely check enough of the surface to be confident the surface is in spec.

The next few Tips will illustrate how easy it is to measure profile of a surface with traditional inspection equipment. Of course, other equipment such as CMMs could be used. The surface located by the 32mm dimension is controlled by the general profile tolerance relative to datum A. Since the 32mm dimension is BASIC, the indicator would be mastered at 32mm relative to the surface plate. When indicating the surface, the indicator may not deviate from 32 by more than ±0.75 (half the total profile tolerance). What could be simpler?

Back to Tips Tip added Jul 2004