Using Explicit Controls on Blend Surfaces

You can use the Explicit Controls options to influence the shape of the blend surface.

Before you begin: Open a 3DShape containing two parallel curves or surfaces with parallel edges.
See Also
About Creating Surfaces from Curves
  1. Create a blend surface as described before.
  2. Select a Flow option:
    OptionDescription
    Radial Depending on the selected Edge Flow option in the Flow Control section, the side edges of the blend surface are perpendicular to Rail A or Rail B. In case of support curves or edges with unequal length, the blend surface is only partly connected.

    Edge Flow Rail A

    Edge Flow Rail B

    Natural The blend surface connects the two input curves Rail A and Rail B over their full length.

    Equal Angle The blend surface connects to the point on the opposite edge in which the angle between connecting direction and tangent in this point is equal to the angle at the starting point.
    RadialX Rotates Rail A or Rail B around the z-axis, depending on the selected Edge Flow option.
    RadialY Rotates Rail A or Rail B around the x-axis.
    RadialZ Rotates Rail A or Rail B around the y-axis.
    RadialP Rotates Rail A or Rail B around the z-axis of the current plane.
  3. Change the default Blend Bias value to 0.1 and 0.9.
    With a small Blend Bias value, the blend surface is more copped at Rail A and more flat at Rail B, and vice versa with a high value.

    Blend Bias 0.25

    Blend Bias 0.5

    Blend Bias 7.5

  4. Specify a Boundary Offset (uniform) value.

    This option is only available, if surface edges or projected curves are selected as input geometry.

    Depending on the selected mouse menu option (see Manipulating a Blend Surface), the blend surface boundary or boundaries are moved to the interior of the support surface or surfaces.

  5. Select Tubing.


    The blend surface is created with a constant radius. You can use the default profile radius or specify a user-defined radius in the text box.
    Important:
    • To be able to connect the blend surface edges with those of the support surfaces, the radius must not be lower than a minimum value. If no blend surface is created, increase the radius value or use the Initialize option.
    • The continuity at the transitions to the support surfaces is always G0 and cannot be modified.
    • Blend Bias cannot be used.
  6. Click Initialize.


    The blend surface is calculated with the optimal radius.
  7. Select Flip to invert the tubular surface orientation.