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A fillet is a curved face of a constant or
variable radius that is tangent to, and that
joins, two surfaces. Together, these three surfaces form either an inside
corner or an outside
corner.
In drafting terminology, the curved surface of an outside corner is
generally called a round and that of an inside corner is normally referred
to as a fillet.
Edge fillets are smooth
transitional surfaces between two adjacent faces.
The purpose of this task is to fillet several edges. First you will
fillet nine edges, then you will fillet a face and trim this fillet to a
plane. The cases illustrated here are simple. They use a constant radius:
the same radius value is applied to the entire edges. To see more complex
fillets, refer to Creating Variable Radius
Fillets or Variable Radius Fillet
Using a Spine.
This document deals with the following:
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Open the
Edge_Fillet1.CATPart document. |
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How to Fillet Edges
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Click Edge Fillet
in the Dress-Up Features toolbar (Fillets
sub-toolbar).
The Edge Fillet Definition dialog box
appears.
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Select the edge as shown. The edge selected then appears
in the Object(s)
to fillet field. The application displays the radius value. Clicking Preview previews the
fillet to be created.

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The icon now
available after the Object(s)
to fillet field lets you edit the
list of the faces to be filleted. For more information about that
capability, refer to
Editing a List of Elements. |
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Select the Selection mode as Tangency.
The preview clearly shows that the whole edge will be filleted.

If you set the Tangency mode, the Trim
ribbons option becomes available: you can then trim the fillets to
be created. For more, refer to Trimming ribbons.
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The Selection mode available are:
- Minimal: Edges tangent to selected edges can be
taken into account to some extent. The application continues
filleting beyond the selected edge whenever it cannot do otherwise.
In our example below, the fillet is computed on the selected edge
and on a portion of tangent edges:
- Tangency: Tangencies are taken into account so as to
fillet the entire edge and possible tangent edges.
- Intersection:
This selection mode fillets all the edges created by the
intersection of the faces of the selected objects and the rest
of the faces of the current body. This mode is based on the selection of features, while the other
selection modes Minimal and Tangency are
based on the selection of edges or faces.
For more information, see
Filleting Intersection Edges.
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Enter 15mm as the new radius value. The radius value is
updated in the geometry area.
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Select the eight vertical edges.

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Click OK. The edges are filleted. The creation of this fillet is indicated in the
specification tree.
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Click Edge Fillet
again and select the upper face as the new element to be filleted.
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Enter 5mm as the radius value.
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Click More to access
four additional options.
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To know how to use: |
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Limiting
Elements
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Click the Limiting element
field and select Plane.1 as the plane that will intersect the
fillet.
An arrow appears on the plane to indicate the portion of material that
will be kept. Clicking this arrow reverses the direction and therefore
indicates that the portion of material that will be kept will be the
opposite one.
This capability is supported on Part Design P2 only.
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Click OK.
The second fillet is trimmed to Plane.1. Both fillets are displayed in
the specification tree. The final part looks like this:
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Select the
Conic
parameter
check box 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.
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If the conic mode is activated, the
Edge(s) to keep
and the Parting element
fields cannot be selected.
The Conic parameter option
is not available when a parting element is already defined
or the edge to keep is either explicit or implicit in
nature.
- Conical fillets do not handle twist configurations. If a
twist is detected, the fillet
operation fails.
- If the
fillet surface curvature is lower than the support
curvature, fillet surface
relimitation may fail.
In this case decrease the
Conic
parameter.
- The Parting Element
option is grayed out, when the CFO license is not available.
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Filleting Intersection Edges
Filleting intersection edges capability allows you to fillet
edges in a more productive way by reducing the number of
selections.
Select the Intersection option from the
Selection mode field in the Edge Fillet Definition
dialog box. Now if you select any part design feature, all
the sharp edges at the intersection of this feature with the current
solid are automatically filleted with the given radius value. You can
select one or more features at a time. The selected feature appears in
the Object(s)
to fillet field and the other feature becomes a current solid.
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Feature selection showing all edges at the intersection |
Intersection Fillet |
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- The selection of a body used in a Boolean operation is not
allowed. In order to get the intersection edges of an operated body, you
need to select the corresponding Boolean operation or one of its
features. This selection must be done from the specification tree only.
To get the intersection edges of an operated body (Body.2),
select Assemble.1 created from a boolean operation. You can
also directly select the features (Pocket.1 and Pocket.2) of this
body.
- If a pattern is selected, only the instances of the pattern
are filleted. So it is necessary to add the parent shape of the pattern
to the list of objects to be filleted.
- If you have selected edges in Tangency or
Minimal mode, you can change the Selection mode to
Intersection. In this case selection is cleared and Candidate features
dialog box appears which gives you option to select the features that
contains these edges. The selected feature appears in the Object(s)
to fillet field.
- The Blend corner(s) option is not available with
the Intersection selection mode.
- This capability takes into account the tangency of the edges
to be filleted.
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Interrupting Fillet Computations
In case you made a mistake when
defining a fillet (wrong radius value for example), you can interrupt the
feature computation launched after clicking OK, when the
computation requires a few seconds to perform.
In concrete terms, if the computation exceeds a certain amount of time, a
window appears providing a Cancel option. To interrupt the
operation, just click that Cancel button. This interrupts the
process and then displays an Update Diagnosis dialog box enabling you to
edit, deactivate, isolate or even delete the feature.
This new capability is available for any types of fillet features you
are creating or editing. |
Keeping Edges
When filleting an edge, depending on
the radius value you specified the fillet may affect other edges of the
part that you do not want to fillet. In case you can anticipate such a
result, before confirming the Fillet operation, specify the
edges you want to exclude from the operation by filling in the Edges
to keep field.
In the example below, the user selects the upper edge as
the edge to keep. Once selected, this edge turns purple.
Edge to be filleted |
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The upper edge is selected
as the edge to be kept |
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The upper edge is not
filleted
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Note: Selecting
an edge as an edge to be kept can propagate the selection of edges to be
filleted. Propagated edges are displayed in red dotted lines. In the
example below, both pink colored edges are selected as edges to be kept. The
selection of the edge to be filleted (in red) then includes two additional
edges.
Selection of the edge to fillet and of two edges to
be kept |
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Result |
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If an Error Message is Issued...
In case you have specified no edges you want to exclude from the fillet
operation, the application may sometimes detect that some edges cause
trouble during the fillet computation. The
application then issues an error message asking you if you wish to select
the edges you do not want to fillet.
There are two ways of specifying the edges you want to keep:
- By explicitly specifying these edges
This means that you need to click Yes in the Feature
Definition Error dialog box. Then you just need to click the
Edit button from the Update Diagnosis dialog box that
appears, click the Edges to keep field from the Edge
Fillet dialog box and select the edge in the geometry. The
application then displays the selected edge in pink meaning that the edge
will not be affected by the fillet operation. The fillet is eventually
computed and does not affect the "keep" edge.
- By letting the application find a solution
If you do not wish to explicitly select the edge you do not want to
fillet, just click No in the Feature Definition Error
dialog box. The application then tries to find a solution.
Both methods may not give the same result depending on the geometry. If
you prefer to let the application find a solution, the application finds an
appropriate physical edge in the geometry, then considers it as the edge to
be kept. If no edge can be found, then it finds a solution by itself. |
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: |
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An error message
is issued, prompting you to select an edge adjacent to the filleted edge.
Just by selecting both edges to the right and the left of the previewed
fillet, the application can then compute the whole fillet properly: |

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Trimming Ribbons
If you choose to use the Tangency propagation mode, you can
also trim overlapping fillets. To do so, simply check the "Trim
ribbons" option.
Selected edges
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Overlapping fillets are not trimmed
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Both fillets are trimmed
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Compare the above results to the fillets created with the
Minimal propagation mode: The fillets are only trimmed.
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