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Introduction to Model Based Definition with Creo Parametric 7.0
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Planning for Dimension Annotations

Plan orientations while considering dimension display.

  • Primary view orientations

  • Orientation considerations

  • Dimension display

  • Datum usage

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Figure 1 - Changing Z Depth

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Figure 2 - Obscured Dimension

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Figure 3 - Offset Lines

Planning for Dimension Annotations

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Figure 2 - Obscured Dimension

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Figure 3 - Offset Lines Planning model view orientations for annotation is related to the number and types of features in the model. Model view orientations are analogous to views in a drawing except that with an isometric (non-orthographic — front, top, right) orientation, you can display much more information without having to create section views and detail views.

For fully dimensioned models, the base features and profiles are usually dimensioned in the first of the #7 series combined states. Other unique model features are dimensioned in subsequent combined states.

Before creating annotations, plan the model orientations while considering various aspects of dimension display as the following:

  • Text direction

  • Text location

  • Annotation placement plane

  • Obscuring dimensions

  • Extension lines from dimensions

  • Note leader attachment location

Dimension Display

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Figure 1 - Changing Z Depth

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Figure 4 - Option 1

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Figure 5 - Option 2

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Figure 6 - Option 3 Dimension display should also be considered. When dimensioning in 3-D, your leaders may run through solid geometry, leading to the following considerations:

  • Can leaders or the ends of leaders be obscured?

  • Can dimensions refer to features at different Z depths?

  • As a Creo MBD best practice, the leader or extension line should always be visible. You can change the Z depth of the annotation, and the system will create z-extension lines.

  • Company best practices may dictate the Z depth plane on which the dimension should lie.

The following figures illustrate three options for a dimension in the same view orientation:

  • The first option has the dimension completely overlaying the geometry. This is adequate for detail views or for when the view is zoomed in such that an off-model dimension would not be scaled well but the dimension and feature are clear. As a Creo MBD best practice, this should be considered the last option. Whenever possible, dimension lines should not be completely surrounded by part geometry.

  • The second option displays the dimension text off the geometry with the leaders over the model. As a Creo MBD best practice, this should be considered the second choice option. Extension lines and part of the dimension line cross over geometry in this case.

  • The third option, which is preferred, displays the dimension text and dimension line off the model with only a portion of each leader over the model geometry. Ideally, you should display as much of the dimension away from the model as possible. As a Creo MBD best practice, this should be considered the preferred option. Only extension lines cross over geometry in this case.

Datum Usage

When creating annotations, the question of using primary model datums (default datums FRONT, TOP, RIGHT) as datum feature symbols often arises. A common alternative is to create a new and separate datum plane for annotation purposes.

As a Creo MBD best practice, do not use the primary datums for datum feature symbols. Where possible, it is recommended to select a flat surface of the model on which to place datum feature symbols for geometric tolerances on geometry.