Creating Edge Fillets

 

Edge fillets are useful to provide a transitional surface along a sharp internal edge of a surface.

This task shows how to create a constant radius fillet along the internal edge of a joined surface.
The fillet surface is obtained by rolling a sphere over the selected edge.
 

Open the EdgeFillet1.CATPart document.

  1. Click Edge Fillet .

    The Edge Fillet Definition dialog box appears.

  2. Select the edge to be filleted.

    You can also select a face, provided there is no ambiguity as to the edge(s) to be filleted.

  3. Use the combo to select the desired type of extremity for the fillet:

    • Straight: no tangency constraint is imposed at the connecting point between the fillet and the initial support, generating sometimes a sharp angle

    • Smooth: a tangency constraint is imposed  at the connection between the fillet surface and the support surfaces, thus smoothing the connection
    • Maximum: the fillet surface is limited by the longest selected edge
    • Minimum: the fillet surface is limited by the shortest selected edge
    (Refer to Shape Fillets)

  4. Enter the value of the fillet Radius.

    A preview of the fillet appears.

  5. You can choose the Propagation type:

    • Tangency: the fillet is propagated up to the first edge that is not continuous in tangency.

    • Minimal: the fillet is propagated up to the first geometric limitation.

    • Intersection: the fillet is propagated to all the edges that have been generated by intersecting the features.
       
       If propagation mode is switched to Intersection and if Intersection edges activation or C1 Intersection edges activation icon is not selected in the User Selection Filter toolbar, a warning message is displayed, and a continuous in tangency Intersection Edge is created by default. For further information, refer to Selecting Using A Filter in the CATIA Infrastructure User's Guide.

       

  6. Select the Conic parameter check box. This check box allows you to vary the section of the fillet.

    For a parameter comprised between or equal to:
    •  0.5, the resulting curve is a parabola.
    • 0 < parameter < 0.5, the resulting curve is an arc of an ellipse
    • 0.5 < parameter < 1, the resulting curve is a hyperbola.
    • Conical fillets do not handle twist configurations. If a twist is detected, the fillet operation fails.
    • Conical fillets may produce internal sharp edges. However, healing is used to smooth these sharp edges. Refer to Healing Geometry for more information.
    • If the fillet surface curvature is lower than the support curvature, fillet surface relimitation may fail. In such cases, the conic parameter has to be decreased.

  7. You can check Trim support to relimit the support elements and assemble them to the fillet.

  8. Click OK to create the fillet surface.

    The surface (identified as EdgeFillet.xxx) is added to the specification tree.
    Note that the selection of the feature prevails over the selection of the sub-element.
    To select a sub-element, you need to apply the ''Geometrical Element'' filter in the User Selection Filter toolbar.
    For further information, refer to Selecting Using A Filter in CATIA Infrastructure User's Guide.
 

Keeping Edges

  You may also need to explicitly indicate edges that should not be filleted, if a radius is too large for example. In this case you cannot select boundary edges to be kept, but only internal edges, i.e. edges limiting two faces.
Open the EdgeFillet2.CATPart document.
 

To do this, proceed as above, but once you have selected the edge to be filleted, click More>> to expand the dialog box, then select the edge(s) you wish to keep in the Edge(s) to keep field.
 

 

If you have difficulties selecting the edge, use the up/down arrows to display the preselection navigator.
CATIA displays this edge in pink, meaning that it will not be affected by the fillet operation.
 

If the Conic parameter check box is selected, the Edge(s) to keep field is grayed out. Conversely, if the Edge(s) to keep field is selected, the Conic parameter  check box is disabled.

Limiting Fillets
While creating the fillet, you can limit it by selecting a surface that intersects it completely:

  1. Once the edge to be filleted has been selected, and the radius keyed in, click Preview then More>>.

  2. Click in the Limiting element(s) field, then select the trimming element(s).

    These elements can either be surfaces, planes, or points on edges. 
    An arrow indicates which portion of the fillet is to be retained.
    • You can use one or more limiting elements.
    • You can define a limiting element just by clicking a point on one of the selected edges to be filleted.

  3. Click on this arrow to inverse it, if needed, to retain the opposite side of the fillet.

  4. Click OK to create the limited fillet.

    In the illustration, the limiting surface has been hidden.
    You can create limiting elements just by clicking on the edge to be filleted. 
    The application displays this element as a blue disk.
    • You can select planes or points as limiting elements. Points must be located on the edge to be filleted and they must have been created using the On curve point type available in the Point Definition dialog box.
    • Make sure the limiting element is not larger than the initial element, as illustrated here. If so, decrease the size of the limiting element as prompted by the warning message.
 

Ignoring Edges

  When the update process detects that sharp edges (edges are considered as sharp when the angle between the two faces is greater than 0.5 deg) interrupt fillet operations, it is possible to continue filleting just by selecting an edge adjacent to the edge to be filleted. In the example below, the application displays the edge causing trouble in yellow:
 

  An error message is issued, prompting you to select an edge adjacent to the filleted edge. Just by selecting the edge to the right of the previewed fillet, the application can then compute the whole fillet properly:
 

 

Creating Tangent Intersection Edges

   

Trimming Overlapping Fillets
In some cases, fillets may be overlapping. The Trim ribbons option lets you solve this by trimming the fillets where they overlapping.

Open the EdgeFillet3.CATPart document.

  1. Click Edge Fillet and select the edges at the base of the cylinder and the one along the vertical surface.

  2. Click Preview.

    The two fillets clearly overlap.

  3. In the Edge Fillet Definition dialog box, check Trim ribbons and click OK.

    Note that Trim ribbons is available with the Tangency and Intersection edges propagation mode: 
    • In Minimal mode, Trim ribbons is grayed, as it is implicitly active. The results would be trimmed fillets, and no propagation.
    • In Tangency mode, with Trim ribbons deselected, the fillets intersect, with no trimming, and the propagation is performed.
    • In Tangency mode, with Trim ribbons checked, the fillets are trimmed and the propagation is performed.

 

Filleting Volumes

Open the FilletingVolumes1.CATPart document.

  1. Click Edge Fillet .

    The Edge Fillet Definition dialog box appears.

  2. Select the edge to be filleted.

  3. Set the Radius to 10mm.

  4. Click OK to create the fillet volume.

    Extremities and Trim support are grayed out. They cannot be used with volumes.