Creating an Offset Constraint

	When defining an offset constraint between two components, you need to specify how faces should be oriented. The offset value is always displayed next to the offset constraint.
	The unit used is the unit displayed in the Units tab of the Tools -> Options dialog box. If you wish, you can customize it.
	The following table shows the elements you can select:

	Point	Line	Plane	Planar Face
Point
Line
Plane
Planar Face

This task consists in applying an offset constraint between two faces.

Before constraining the desired components, make sure it belongs to a component defined as active (the active component is blue-framed and underlined).

Open the AssemblyConstraint02.CATProduct document.

Click the Offset Constraint icon

This command is also available from the Insertmenu.

Select the face to be constrained, that is the yellow face as shown.

Select the second face to be constrained, that is the blue face in the direction opposite to the yellow face.

Green arrows appear on the selected faces, indicating the orientations.

The Constraint Properties dialog box that appears displays the properties of the constraint. The components involved and their status are indicated. You can define the orientation of the faces to be constrained by choosing one of these options:

	Undefined (the application finds the best solution)
	Same
	Opposite

Note that when changing a 'Same' orientation into an 'Opposite' orientation or vice-versa, the application may sometimes positions the parts in an unexpected way especially if your system is under-constrained.

For the purposes of our scenario, keep the Opposite option.

Enter 38 mm in the Offset field.

Click OK to create the offset constraint.

A green arrow is displayed in the geometry area to indicate that this constraint has been defined. The offset value is displayed too.

This constraint is added to the specification tree too.

Graphic symbols used for constraints can be customized. For more information, refer to Constraint Creation .

Positive and Negative Offsets

When setting an offset constraint, you can define positive or negative offset values. For this, remember that:

at least one of the components to be constrained must be a planar element, otherwise you cannot set positive nor negative offset values.

the vector normal to the planar element indicates the positive offset value.

- If the planar element is an oriented plane, the normal vector pointing to the side opposite to material indicates the positive value.

- if the planar element is a wireframe plane, the application automatically deduces the positive or negative value. Green arrows show the positive value.

if both components are planar elements, the selection order of the elements affects the result when using the orientation option (Same, Opposite, Undefined). The normal to the first selected element gives the positive value.