Fig Specifying Runout Relative To Two Datum Oiameters

of sufficient length. Figure 6-47 incorporates the principle of circular runout tolerancing and illustrates the control of circular elements of a surface. Figure 6-48 incorporates the principle of total runout tolerancing and illustrates the control of an entire surface. Two Datum Diameters. Figure 6-49 illustrates application of runout tolerances where (wo datum diameters collectively establish a single datum axis to which the features are related. Diameter and Face Datums.

Where features to be controlled are related to a diameter and a face at right angles to it. each related surface is assigned a runout tolerance with respect to these two datums. The datums are specified separately to indicate datum prcccdencc. See Fig. 6-50. This figure incorporates the principles of both methods of specifying runout tolerances. Control of Individual Datum Surfaces. It may be nccessary to control individual datum surface variations with respect to flatness, circularity. parallelism, straightness, or cylindricity. Where such control is required, the appropriate tolerance is specified. See Figs. 6-51 and 6-52 for examples applying cylindricity and flatness to the datums. Control of Runout to a Datum

Feature(s). Where datum features are required by function to be included in the runout control, runout tolerances must be specified for these features. See Figs. 6-51 and 6-52. Relationship of Features Based on Datum Sequence. Features having a specific relationship to each other rather than to a common datum axis are indicated by appropriate datum references within the feature control frame. See Fig. 6-51. In this example, the runout tolerance of the hole is related to datum E rather than the axis C-D. Surface Relationthip. Where two surfaces are related to a common datum by runout tolerances. the permissible runout between the two surfaces is equal to the sum of their individual runout tolerances with respect to the datum. Specification. Multiple leaders may be used to direct a feature control frame to two or more surfaces having a common runout tolerance. Surfaces may be specified individually or in groups without affecting the runout tolerance. Sec Fig. 6-51.

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