Datum Features Must Be Referenced to Be Used (#208)
(In accordance with Y14.5M-1994 standard)
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There continues to be the misconception that if a feature is labeled as a datum feature, its use is somehow implied. Take the drawing shown. The position tolerance on the hole references datum features A and B but not C. Therefore the hole must be perpendicular to the plane established by datum feature A and 20 mm from the axis established by …
