Position Can Control Location of Irregular Features (#130)
(In accordance with Y14.5M-1994 standard)
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The October 2000 Tip illustrated how to control the location and orientation of irregular and complex features using a Profile of a Surface control with datum references. This type of feature may also use Position to control location and orientation relative to datum references. On the drawing below, the Profile of a Surface callout controls the size and form of the hex while the Position callout is controlling the location and orientation of the hex. Since this callout includes the maximum material condition modifier and the BOUNDARY note, a hard gage may be used to inspect the Position control. The only difference between this inspection gage and the one shown in last month’s Tip is that the outer boundary need not be checked. Therefore, the NO-GO wire required when Profile of a Surface had been used is not needed for this Position control. Only the inner boundary has to accept the gage to verify the position requirement.
The figure shown below is a possible gage that might be used to inspect the position tolerance. The values shown are theoretical design values, which do not include gage tolerance and wear allowance.
