(In accordance with Y14.5M-1994 standard)
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It really does matter where you place a geometric tolerance. Often it can change the meaning. Other times it can be just plain wrong. Profile of a surface is often applied incorrectly. It is called “profile of a surface”. It applies to a feature’s surface. Therefore, it must be applied to surfaces on a drawing.
On this drawing, two profile of a surface tolerances have been applied incorrectly. They are shown crossed out on the drawing. The profile of a surface tolerance labeled “OK” illustrates proper application of a surface control.
Applying a geometric tolerance to a size dimension usually is controlling the axis or center plane. Profile of a surface never controls an axis or center plane. It is easy to do it right.
Back to Tips Tip added Jul 2008