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3D constraints are defined by means of one of the two
constraint
commands available in this workbench. Depending on the creation mode chosen
for creating wireframe geometry and surfaces (see Wireframe and Surface
User's Guide), constraints set on these elements may react in two ways.
You create references if support elements were created
with the Datum mode deactivated. Conversely, you create
constraints if you constrain datums. For more about datums, refer
to
Creating Datums.
The constraints
you can set in Part Design workbench are:
This task shows you how to set a distance constraint between a face and
a plane, then a reference between the face and another plane. |
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Open the
Constraint1.CATPart document. |
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Select the face you wish to constrain and Plane.1.
This plane is a datum (there are no links to the other entities that were
used to create that plane).
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Click Constraint
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The application detects the distance value between the face and the
plane. Moving the cursor moves the graphic symbol representing the
distance.
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Click where you wish to position the constraint value.
The constraint is created.
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- The name of a
constraint displays when passing the mouse over that constraint.
- The application does not display constraints when these are too
small. More precisely, the constraints visualization depends on the types
of constrained elements. This means that when zooming out, a constraint
set between two points is more likely to disappear than a constraint
between two lines.
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Now, set another constraint between the same face and
Plane.2. Plane.2 is not a
datum. Repeat the instructions described above
using the face and Plane.2.
The application creates a reference.
Creating a reference means that each time the application integrates
modifications to the geometry, this reference reflects the changes too.
The reference is displayed in parentheses as
shown below:
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You cannot set a distance constraint between
two faces belonging to Part Design features linked by their specifications.
In the example below, the application creates a reference between the
faces, not a driving constraint. |
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To know how to modify a constraint, refer to
Modifying Constraints. |
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Note
You cannot view constraints if the plane in which they are
located is normal to the screen. In that case, you just need to use the
mouse, for example, to rotate the view and therefore make the
constraints visible. |