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The Nominals tab of the Geometric Tolerance dialog box is available for position tolerances and for geometric tolerances that have a size tolerance.
It looks like this:
This list controls the coordinate system that the nominals are reported in. You can switch between Datum Reference Frame and Current Alignment to change the nominals that you see.
After you click OK or Create, PC-DMIS changes the coordinate system that the results are reported in.
You can visualize the two coordinate systems in the Graphic Display Window, like this:
In the example picture above, the trihedron for the current alignment is at the center of the part. The trihedron for the datum reference frame coordinate system is shown in the upper bore.
The trihedron does not update dynamically while you use the Geometric Tolerance dialog box. You need to click Create or OK to see the updated trihedron.
The table of items allows you to do the following:
View the nominal locations of the considered features in the chosen display coordinates.
Control the size tolerances of the considered features and datum features.
Control which axes to include in the report.
You can control which considered feature to view with the tabs on the left. Each feature has a small tab that you can click on, like this:
Each feature's tab lets you view the nominal location of that considered feature.
The Report Axis column of the nominals table determines whether to include that axis in the report. You can mark the check boxes to show the desired information.
The Axis column of the nominals table contains the names of the axes you may want to report. These names stand for the following items:
X - This means the X coordinate.
Y - This means the Y coordinate.
Z - This means the Z coordinate.
PR - This means the polar radius.
PA - This means the polar angle.
DF - This means diameter of the feature (or size).
As you can see in the image below, the datum names are also in the axis column:
Only datum features of size appear. The Report Axis check box is not available for these rows.
The Nominal column of the nominals table contains the nominal values of the reportable axes, and the nominal sizes of the datum features of size.
The +Tol column of the nominals table contains the plus size tolerances of the considered features and datum features of size. You may edit the plus size tolerances here.
The -Tol column of the nominals table contains the minus size tolerances of the considered features and datum features of size. You may edit the minus size tolerances here.
The Minus Tols Show Negative check box on the Dimension tab of the Setup Options dialog box applies the same here as it does in the Feature Control Frame tab. For information, see the "Feature Control Frame Tab" topic.
When it is cleared, the minus tolerances are typically positive.
When it is selected, the minus tolerances are typically negative.