Radius dimensions show the radius of a selected element; and diameter dimensions, not surprisingly, show the diameter of an element. Valid reference elements are cylindrical faces, circular edges and toroidal faces. Other faces and edges are not valid reference elements and cannot be dimensioned.
The reference positions are the center points of the radial or circular elements you click. The extension line extends to the circumference of the element, but you have the option also to include a centerline through the center point.
You can create dimensions measuring radii or diameters to circles, arcs, cylinders, spheres, and tori on parts and profiles. Note that a radius or diameter dimension on a circular edge does not allow 3D modifications by label.
When you dimension tori, you have the option to measure the major diameter/radius (measured from the toroidal axis) or the minor diameter/radius (measured from the center of the torus proper). These options become available once you have specified the dimension reference on the torus.
For free dimensions, Creo Elements/Direct Modeling places the display plane automatically at the reference position parallel to the measured radius. You can also specify a docuplane if it is valid for the dimension. You can reposition a dimension label only within its display plane or docuplane.
The figure below shows an example of radius and diameter dimensions.
To create a radius or diameter dimension,
1. Click 3D Documentation and then, in the Annotate group, click the arrow next to Circular.
2. Click Radius or Diameter. The Create Circular Dim dialog box opens.
3. If necessary, specify whether you want to create a Generic dimension or GD&T by clicking the appropriate tab.
4. Select whether you want to create a Radius or a Diameter dimension.
5. Clear the Centerline check box if you do not wish to add a line from the center of the element to meet the extension line, which leads to the circumference of the element.
6. Click the reference for the dimension. The selected reference is highlighted, the extension lines of the dimension label snap to the center point of the element, and the dimension label becomes attached to the cursor. Note that the dimension value is displayed in the Dim Value box, which updates dynamically as you alter the current dimension.
7. Specify the measure direction and placement of the dimension:
◦ To create a free dimension, select Free under Orientation/Placement, and click a position for the dimension label. The plane of the dimension is determined by its reference point.
◦ To place the dimension on a docuplane, click Docuplane and specify the docuplane to use (double-click it in the browser, or click it in the viewport). The active docuplane, if present, is selected by default.
After placing the dimension label, you can click it or any other label to move it and click another position. This is allows you to organize labels "on the fly".
8. Select or type the radial prefix in the Radial Prefix box. A radial prefix is usually a character and it appears between the prefix and the value of the radius or diameter dimension.
9. If necessary, you can add tolerancing information to the dimension.
10. You can include a prefix, postfix, subfix, or superfix with the dimension value by expanding the Text fixes area and entering text into the appropriate boxes.
11. You can use predefined tolerances and/or text fixes in two ways:
◦ Presets: Click this to open a table containing values that were stored earlier.
◦ Grab: Click this and then click an existing dimension in the viewport. The tolerance and text fixes of the selected dimension are copied into the menu and used for the current dimension.
12. If you are creating a GD&T dimension, you must also specify a Name for it. Optionally, you can also include a Descr, dimension critical Identifiers, or Insp. Notes. These will be shown in feature reports.
13. You can add a URL to a dimension text, which can be any file on your local computer, network, or the public Internet. The file will open in its default viewer when you right-click the dimension, then click Display URL.
14. You can end the current dimension in one of two ways:
◦ Click Next to complete the current dimension and continue creating new dimensions with the same tolerance and text fixes.
You can avoid clicking Next; once the current dimension is complete, simply click a new reference on the model to define a new dimension. The system will automatically make this the current dimension using the current settings.
◦ Click Reset to cancel the current dimension but keep the menu open with the same tolerance and text fixes.
15. When you are finished creating dimensions, click to complete the operation.
When you dimension a torus, you can measure the radius of either the Major or the Minor circle.
Circular.
Diameter. The Create Circular Dim dialog box opens.
to complete the operation.