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Profile - Coplanarity
Another Coplanarity Tip

   For Coplanarity use Profile.

Flatness is an individual control. When you want multiple surfaces to lie in the same plane the Y14.5 Standard says to use profile. Many designers and engineers think that if flatness is used in conjunction with an extension line, it means that the surfaces must be contained within two parallel planes with a maximum separation not greater than the specified flatness tolerance. As illustrated, however, this is not the correct interpretation.

The desired condition is called coplanarity. The correct method to control coplanarity of multiple features, is by using profile as illustrated below. 

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