Lofted Features

A lofted feature creates a body by fitting surfaces between a series of profile sketches.

The cross-section of this body varies along the length of the feature according to the shape of each profile sketch. The start and end sketches define the faces that cap either end of the solid body. You require a minimum of two sketches to create a single loft.

A lofted cut is defined in the same way; the volume that is defined by the lofted profile is subtracted from any bodies through which it cuts. You can only use lofted cuts on solid bodies.

When 3D-CAD creates the lofted feature, it matches each vertex on one sketch with a vertex on the next sketch, and fits curves through the pairs for the fitted surfaces. You can manually control which vertices make up these pairs using a feature called Vertex Matching. This technique is useful when you are creating a loft between several sketches, between sketches that have complex geometry, or to define an alternative loft path.

You can further control the shape of the loft by using guide wires. This feature enables you to create complex shapes with twists along the length of the solid.

Requirements

The following criteria must be satisfied for the loft to complete successfully:

  • Each profile sketch must contain a single, closed loop to define the shape of the loft.
  • The number of points that lie on the closed loop must be the same for each sketch, unless, for two consecutive sketches, one loop has no points, such as a circle or ellipse. For lofting, splines are considered to have no points. In this case, a loop that defines a single, closed spline is treated in the same way as a circle or ellipse, regardless of the number of points on the spline.

Some examples of the closed loops that can be used to created lofts are shown in the following images:

  • A circle and an ellipse (two closed loops that contain no points):

  • A circle and a polygon (a closed loop with no points and a closed loop with any number of points):

  • Two polygons (two closed loops that have the same number of points):

When designing a lofted feature, observe the following points:

  • Sketches can lie on sketch planes that are oriented in any direction, but no two consecutive sketches can lie on the same plane.
  • You cannot create a lofted feature that passes through itself at any point.
  • The shape and position of sketches must avoid any radical changes in the cross-sectional profile of the body.
  • Ensure that sketches do not result in any self-intersections in the solid body.
  • Construction lines have no impact on the loft.