Angularity Does Not Locate - Use Profile of a Surface (#206)
(In accordance with Y14.5M-1994 standard)
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Here is another case where angularity cannot fully define the feature. The original drawing had angularity rather than position applied to the 10 mm wide slot. The drawing shows that the center of the slot should be in line with datum axis B. Angularity would assure that the slot is at the 60° basic angle but ignore that the slot center plane should pass through the datum axis. To keep the slot in line with the datum axis, position needs to be applied to the slots size dimension. If the angle of the slot needs to be controlled better than the angularity provided by the position tolerance, an angularity tolerance may be added as a refinement. As we teach in our GD&T seminars, for features of size, locate first with position and refine with orientation, in this case angularity, only if necessary.
