Creating Tri-Tangent Fillets

This task shows how to create a fillet surface tangent to three surfaces. Specifying a radius is not necessary as the fillet radius is defined by these surfaces.

Open the TriTangentFillet.CATPart document.

  1. Click the Tri-Tangent Fillet icon .
    The Tri-Tangent Fillet dialog box is displayed.
 

  1. Select Suface.1 and Surface.2 as Support and Surface.3 as Limit.

    Note: The region where the fillet will be created is defined by the normals of the selected surfaces. If necessary, the normal alignment must be modified to enable the fillet creation:
 

  1. Click OK to create the fillet surface.
You can define the following options:
  • Support 1: Selects support 1.
  • Support 2: Selects support 2.
 
  • Limitation: Specifies the limiting element used for the calculation of the Tri-Tangent fillet.
    The fillet calculation is based on an imaginary ball rolling at support 1 and 2 along the limitation.
  Options tab
 
  • Continuity: You can specify three continuity settings for the resulting fillet:
    • G1: Tangency continuity is maintained between the fillet and support surfaces.
    • G2: Curvature continuity is maintained between the fillet and the support surfaces.
    • G3: Torsion continuity is maintained between the fillet and the support surfaces.
 
  • Fillet offset: Selecting this option changes the icon display:


    Modifies the center position of the spherical ball fillet radius. A theoretical offset of the limit (s) in either direction (positive + or negative -) is created.
Offset in positive direction Offset in negative direction
  Extensions
  • Extrapolate: If the connecting edges of the support surfaces have different lengths, the fillet surface can be extended to the exterior edges of the support surface with the larger extent. The extrapolation can be activated for the start and/or end edge curves of the fillet.
 Extrapolate cleared

Extrapolate Start selected

Extrapolate Start and End selected

 
 
  • Match end: The start and/or end curve of an extrapolated fillet surface (Extrapolate selected) can be matched to the exterior edges of the support surfaces creating a tangent continuous transition.
 Match end Start selected

Match end Start and End selected

Match end Start and End selected
with trimmed support surfaces

 
 
  • Relimitation: Only active if Extrapolate is selected.
    The fillet surface can be trimmed in two different ways. The fillet surface is the basic surface for the trim operation.
    • Trim Face: The basic surface remains unchanged.
    • Trim Approx:The basic surface changes. The result is not a face.
  • Parametrization: Specifies how the parametrization of the fillet surfaces is influenced. The following options are available:
    • Default: Parametrization is computed automatically.
    • Support 1 / Support 2: Parametrization is taken from the 1st or 2nd set of support surfaces or curves.
    • Stitch: Small elements are eliminated according to the Tolerance set.
    • Average: Inserted segments will be averaged between both initial segments.
  See Approximation tab
  See Output tab
  Click 'More Info' to display deviations and output results.
 
  • Display: Depending on the options selected, values are displayed in the graphics area.
  • U+V: Display of the UV vectors of curves and surfaces.
  • Dynamic, Static, None: See Apply Modes
  • Deviation:
    • Max. support 1/2: Indicates the maximum deviation of the fillet surface from the support surfaces.
    • Max. limit: Indicates the maximum deviation of the fillet surface from the limit.
  • Output Result: See Output Result