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.

2. 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:

3. Click OK to create the fillet surface.

• Support 1: Selection of support 1.
• Support 2: Selection of support 2.

• Limit: Specification of 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 limit.

• Continuity: There are 3 continuity settings available to the user for the resultant Fillet of the feature:
  • 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: When this option is active, the icon display changes:
  
  
  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.

• 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.

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

• Relimitation: Only active if Extrapolate is ON.
  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.
• Parameterization: Specifies how the parameterization of the fillet surfaces is influenced. The following options are available:
  • Default: Parameterization is computed automatically.
  • Support 1 / Support 2: Parameterization 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.

• Display: Depending on the options selected, values are displayed in the graphics area.
• 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.
• UV: Display of the UV vectors of curves and surfaces.
• Output Result: See Output Result