Variable Radius Fillet

Variable radius fillets are curved surfaces defined according to a variable radius. A variable radius corner means that at least two different constant radii are applied to two entire edges.

This task shows how to create a standard variable radius fillet. After performing the scenario, see also Variable Radius Fillets Using a Spine.

Open the VariableRadiusFillet1.CATPart document.
1.   Click the Variable Radius Fillet icon .

The Variable Radius Fillet Definition dialog box appears.

2.  Select the edge to be filleted. You can define variable radius fillets on closed edges. See Variable Radius Fillets Using Closed Edges.

CATIA detects both vertices and displays two identical radius values.

Optionally, click Preview to see the fillet to be created.



Enter a new radius value to simultaneously change the radius of both vertices. For example, enter 12mm.

  The new radius value is displayed on both vertices. The preview is modified accordingly.
Two propagation modes are available:
Minimal: the application does not take any tangencies into account. If filleted edges overlap, the application trims the fillets and creates a sharp edge. 
Tangency: tangencies are taken into account so as to fillet entire edges.
  If you set the Tangency mode, the new option "Trim ribbons" becomes available: you can then trim the fillets to be created. For more, refer to Trimming ribbons
4.  To add a point on the edge to make the variable radius fillet more complex, click the Points: field.

You can also add points by selecting planes. For more information, refer to the end of the task.

You can add as many points as you wish.

5.  Click the Points field then a point on the edge to be filleted.

CATIA displays the radius value on this point.

Note that to remove a point from the selection, you just need to click this point.

6. Enter a new radius value for this point: enter 4. The new radius value is displayed.

This is your preview:


The propagation mode is set to Cubic: keep this mode. To see the Linear propagation mode, refer to "More About Variable Radius Fillets".

8.  Click OK to confirm the operation.

The edge is filleted. The specification tree indicates this creation.

9.  To edit this fillet, double-click EdgeFillet.1 in the specification tree.
  10.  Expand the dialog box by clicking More.

Four additional options are available.

To know how to use:
the Edges to keep option, refer to Keeping Edges.
the Blend corner(s) option, refer to Reshaping Corners.


Limiting Elements

  11.  Click the Limiting element field and select Plane.1as the plane that will trim the fillet.

An arrow appears on the plane to indicate the portion of material that will be kept.

This capability is supported on Part Design P2 only.



It is now possible to use one or more limiting elements.

  12. Click this arrow to reverse the direction and therefore specify that the portion of material to be kept will be the opposite one.
  13. Click OK.

The variable radius fillet is trimmed to Plane.1. The final part looks like this:


You can now create limiting elements just by clicking on the edge to be filleted. 

The application displays this element as a blue disk:

More About Variable Radius Fillets

This is the fillet you would obtain using the Linear propagation mode. Examine the difference!


To add additional points on the edge to be filleted, you can select planes. CATIA computes the intersections between these planes and the edge to determine the useful points.

In this example, three planes were selected.

Now, if you move these planes later, CATIA will compute the intersections again and modify the fillet accordingly.

Points can be added too by selecting 3D points.
You can use the radius value R=0 to create a variable radius fillet.

Variable Radius Fillets Using a Spine

  There may be times when you need to fillet consecutive edges with no tangent continuity but which you want to treat as a single edge logically. You can do this by using a spine. Compare the fillets below:

Standard Fillet

Fillet Using a Spine
  To fillet the edge, the application uses circles contained in planes normal to the spine. It is then possible to control the shape of the fillet.

The spine can be a wireframe element or a sketcher element.

The Generative Shape Design product license is required to access this capability. 


Variable Radius Fillets Using Closed Edges

The application defines a default vertex on closed edges when applying the Edge Fillet command. To define your fillet, first of all you need to remove this vertex, and then use 3D points or planes only.
The Linear propagation mode is not valid for closed edges and edges continuous in tangency.

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