Two Or More Coaxial Features Of Size Inpattern-locating Tolerance

FIG. 5-48 POSITIONAL TOLERANCING FOR COAXIALfTY

coaxiality without excessively restricting the pattern-locating tolerance.

5.11.1.5 Two or More Features in Pattern-Locating Tolerance. Controls, such as are shown in Fig. 5-51, may be specified where it is desired to produce two or more coaxial features within a relatively larger pattern-locating tolerance zone. The central axis of the PLTZF cylinders is parallel to datums A and B. Since the lower (feature-relating) segment of the feature control frame does not invoke orientation datums, the central axis of the FRTZF cylinders may be skewed relative to the central axis of the PLTZF cylinders. Depending upon the actually-produced size of each coaxial feature, each individual feature axis may be inclined within its respective tolerance zone cylinder.

5.11.1.5.1 Orientation of Feature-Ralat-ing Tolerances. Where it is desired to refine the orientation of the FRTZF cylinders as governed by the boundary established by the PLTZF cylinders, datum references specified in the upper segment of the frame are repeated, as applicable, and in the same order of precedence, in the lower segment of the feature control frame. See Fig. 5-52. Since the lower (feature-relating) segment of the feature control frame invokes datums A and B, the common axis of the FRTZF cylinders must be parallel to the common axis of the PLTZF cylinders.

5.11.1.6 Holes of Different Sizes. Where holes are of different specified sizes and the same requirements apply to all holes, a single feature control symbol, supplemented by a notation such as TWO COAXIAL HOLES is used. See Fig. 5-53. The same tolerance zone relationships apply as for Fig. 5-51.

5.11.2 Runout Tolerance Control. Where a combination of surfaces of revolution is cylindrical or conical relative to a common datum axis, or spherical relative to a common datum point, a runout tolerance is recommended. See para. 6.7. MMC is not applicable where a runout tolerance is specified, because runout controls the surface elements of a feature. See para. 2.8.

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