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Introduction to Model Based Definition with Creo Parametric 7.0
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Creating Datum Feature Symbols in Dimensions and Gtols

You can create Datum Feature Symbols in dimensions and geometric tolerances.

  • Select dimensions or gtols.

  • Typically created on the 5_Datums combined state. Add the dimension/gtol to state.

  • System auto-increments the label name.

  • Add semantic references.

  • Additional options.

Figure

Figure 1 - Selecting Dimension to Add to State

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Figure 2 - Datum Feature Symbol in a Dimension

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Figure 3 - Datum Feature Symbol in a Gtol

Creating Datum Feature Symbols in Dimensions and Gtols

Figure

Figure 2 - Datum Feature Symbol in a Dimension

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Figure 3 - Datum Feature Symbol in a Gtol

Figure

Figure 1 - Selecting Dimension to Add to State You can create Datum Feature Symbols in dimensions and geometric tolerances.

  • Datum Feature Symbols placed within dimensions are used to imply a datum plane at the midpoint between the two surfaces. These two surfaces are referenced by the dimension that carries the datum tag. Typically both surfaces should be referenced so that CMMs use them to create the reference Datum Feature Plane.

  • Datum Feature Symbols for cylinders placed within dimensions are used to imply a datum along the axis of a cylinder. The cylindrical surfaces should be referenced so that CMM uses them to create the reference Datum Feature Axis.

  • Datum Feature Symbols placed within geometric tolerances imply a datum in addition to the callout for the geometric tolerance.

The 5_Datums combined state is typically used to display the datum feature symbols. The dimensions and/or Gtols to be used to display the Set Datums can be copied from other combined states to the 5_Datums combined state using Add to State

Figure .

Use the following process to create Datum Feature Symbols in dimensions and geometric tolerances:

  • Select the annotation plane to be used as the Annotation Orientation for the resulting datum plunger.

  • Click Datum Feature Symbol Figure from the Annotations group in the ribbon.

  • Select the desired dimension or geometric tolerance on which to place the datum feature symbol. For selected dimensions, the plunger is created at the middle of the leader by default. You can also select the dimension witness line to place the plunger directly on it at the location where the corresponding leader arrow points to. When a geometric tolerance is selected, the plunger is created at the bottom, middle of the feature control frame by default.

  • Drag the cursor to extend the label and middle-click to place the datum feature symbol.

  • In the ribbon, edit the name as desired from the Label group. The system automatically labels the datum feature symbol the next incremental alphabetical label, but you can also type your own desired label.

  • Add semantic reference surfaces as appropriate.

  • Configure any additional options as necessary.

Geometric Dimensioning and Tolerancing Best Practices

Datum feature symbols should refer to a feature of size, rather than using a datum plane that intersects the middle of many features. It is best to define the primary feature that the dimension refers to. This can be implied by using a dimension, as shown. The implication is that the datum is parallel to the extents of the dimension and is placed at the center of the dimension. Inspection programs also use these two surfaces to create the implied center plane.

Creating Datum Feature Symbols in Dimensions and Gtols

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MBD\Datum-Feature-Symbols

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SENSOR-MOUNT_DATUM_3.PRT

Steps

  • Task 1. Create Datum Feature Symbols in linear dimensions. Disable all Datum Display types.

  • In the ribbon, select the Annotate tab. Select the 7B combined state tab.

  • Select the 2.500 dimension.

  • Select the Annotate tab.

  • Click Add to State Figure from the Manage Annotations group.

  • Select 5_DATUMS from the Assign Annotations dialog box.

  • Click OK .

Figure

  • Click in the background to de-select all dimensions. This action copies the selected item to another combined state.

  • Select the 5_Datums combined state tab. Notice the added dimension.

  • Click TOP Figure from the Annotation Planes group.

Figure

  • Click Datum Feature Symbol Figure from the Annotations group.

  • Select the 2.500 dimension and drag the cursor up.

  • Middle-click to place the datum feature symbol. Figure

  • Notice that the system automatically labeled the datum feature symbol. Datum feature symbols A, B, and C are already present in the model, which is why the system named this newly created datum feature symbol D.

  • Cursor over the plunger and drag the datum feature symbol to the right of the dimension. Figure

  • Right-click and select Change Reference .

  • Select the left 2.500 dimension witness line.

  • Drag and middle-click to place the datum feature symbol. Figure

  • Right-click and select Change Reference .

  • Select the right 2.500 dimension witness line.

  • Drag and middle-click to place the datum feature symbol.

  • Select the dimension and move it closer to the model.

  • Click in the background to de-select all geometry. Figure

  • Select datum feature symbol D .

  • Click References Figure from the References group.

  • Press CTRL and select the two vertical surfaces. Figure

  • Click OK from the References dialog box.

  • Click in the background to de-select all geometry. Both surfaces are now semantic references to the datum feature symbol.

  • Task 2. Create Datum Feature Symbols in radial dimensions. Select the 7D combined state tab. Select the 2.089 diameter dimension.

  • Select the Annotate tab.

  • Click Add to State Figure .

  • Select 5_DATUMS and click OK .

Figure

  • Click in the background to de-select all dimensions.

  • Select the 5_Datums combined state tab. Click ANGLE Figure from the Annotation Planes group.

Figure

  • Click Datum Feature Symbol Figure .

  • Select the 2.089 dimension and drag the cursor down.

  • Middle-click to place the datum feature symbol. Figure

  • Right-click and clear the Dimension Elbow check box.

  • Move the datum feature symbol further out if necessary. Figure

  • Click References Figure .

  • Select one of the inner hole surfaces. Click OK .

Figure

  • Click in the background to de-select all geometry. Both hole surfaces are added as semantic references.

  • Task 3. Create Datum Feature Symbols in geometric tolerances. Select the 7C combined state tab. Select the Flatness Gtol.

  • Select the Annotate tab.

  • Click Add to State Figure .

  • Select 5_DATUMS and click OK .

Figure

  • Click in the background to de-select all geometry.

  • Select the 5_Datums combined state tab. Click LEFT Figure from the Annotation Planes group.

Figure

  • Click Datum Feature Symbol Figure .

  • Select the flatness gtol and drag the cursor down.

  • Middle-click to place the datum feature symbol. Figure

  • Click References Figure .

  • Select the angled surface. Click OK .

Figure

  • Click in the background to de-select all geometry.

  • Task 4. Create Datum Feature Symbols in a Gtol for a dimension with a Gtol. Select the 7D combined state tab. Select the left .375 dimension that contains a Gtol.

  • Select the Annotate tab.

  • Click Add to State Figure .

  • Select 5_DATUMS and click OK .

Figure

  • Click in the background to de-select all geometry.

  • Select the 5_Datums combined state tab. Click ANGLE Figure .

Figure

  • Click Datum Feature Symbol Figure .

  • Select the .375 dimension and drag the cursor down.

  • Middle-click to place the datum feature symbol.

  • Right-click and select DFS Display > On Dimension Elbow . Figure

  • Click References Figure .

  • Press CTRL and select the three small hole cylindrical surfaces. Click OK .

Figure

  • Right-click and select DFS Display > On Dimension .

  • Click in the background to de-select all geometry. Figure If the set datum location is not desired, an alternate method is shown in the following task.

  • Task 5. Create Datum Feature Symbols below Gtol frames. Select the 7D combined state tab. Select the .375 dimension to the right side of the model, then press CTRL and select the nearby Gtol.

  • Click Add to State Figure .

  • Select 5_DATUMS and click OK .

Figure

  • Click in the background to de-select all dimensions.

  • Select the 5_Datums combined state tab. Click ANGLE Figure .

Figure

  • Click Datum Feature Symbol Figure .

  • Select the geometric tolerance and drag the cursor down.

  • Middle-click to place the datum feature symbol. Figure

  • Click References Figure .

  • Press CTRL and select the three small hole cylindrical surfaces. Click OK .

Figure

  • Click the Display group drop-down menu and select the Display per ASME Y14.5m-1982 check box.

  • Click in the background to de-select all geometry. Figure