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You can find a similar function in the Surface Extrude's ability to extrude a 3D sketch. You can also use a regular solid Extrude to extrude a 3D sketch, and it caps the ends for you. While I find all of these extrude options interesting, I have yet to find an application for them. The new ability to extrude a 3D surface duplicates the Ruled surface, although the additional options must be selected manually.

FIGURE 20.4

Extruding a 3D surface

Using Revolved Surface

The Revolved Surface functions like its solid counterpart, right down to the rules for how it handles entities that are touching the axis of revolution; nothing can cross the axis. A single sketch entity is allowed to touch it at a single point, but multiple sketch entities cannot touch it at the same point.

Using Swept Surface

Swept Surfaces work much like their solid counterpart, and the sketch rules and available entities are the same. The main difference here is going to be that Swept Surfaces usually use an open contour for the profile, while swept solids use closed contours.

Identifying the Lofted Surface

The main difference between Lofted Surfaces and lofted solids is that the surfaces can use edges and curve features as profiles, rather than simply sketches and faces.

Using Boundary Surface

The Boundary Surface was created as a higher quality replacement for the Loft feature, but certain limitations mean that Loft has not been removed from the feature list. The Boundary Surface most resembles a loft, but has elements of the sweep. Loft also does a few things that Boundary cannot, such as a closed loop loft without a direction 2 curve, and most importantly, a centerline loft. Boundary Surface can use sketches, curves, or edges in several arrangements, such as curves arranged in an X, F, E, T, L, and other shapes. Figure 20.5 shows some of these shapes.

FIGURE 20.5

Using different curve arrangements with the Boundary Surface feature

If several edge or sketch segments combine to form a curve in one direction, then you must use the SelectionManager to form the edge segments into a group. SelectionManager enables you to select portions of a single sketch or to combine elements such as sketch, edge, and curve into a single selection for use as a profile or guide curve for Boundary or Loft features.

The interface for the Boundary Surface is shown in Figure 20.6.

The types of models where you end up using the Boundary Surface are highly curvy models that are modeled mainly with surface features and require a four-sided patch.

The main advantage of Boundary Surface over Loft is that Boundary Surface can apply a Curvature boundary condition all the way around, while Loft cannot apply curvature continuity across the guide curves. Fill Surfaces also can apply a Curvature boundary condition all the way around.

FIGURE 20.6

The Boundary Surface PropertyManager

Boundary Surface can be a rather nuanced feature, but when working on the type of model that suits it well, I default to Boundary Surfaces when possible. Boundary solid features are also available, and I expect these will also take a little bit of a learning curve to understand where they are best applied.

For a more detailed look at the primary shape creation tools (Sweep, Loft, Boundary, and Fill) and surface modeling in general, please refer to the SolidWorks Surfacing and Complex Shape Modeling Bible (Wiley, 2008).

Characterizing the Offset Surface

The Offset Surface has no solid feature counterpart, but it does in 3D what the Offset Sketch function does in 2D; it may also fail for the same reasons. For example, if you offset a.25-inch radius arc by .3 inches to the inside, it fails because it cannot be offset up to or past a zero radius. The same is true of offsetting surfaces. Complex surfaces do not have a constant curvature, but are more like a spline by having a constantly changing curvature. If the offset is going in the direction of decreasing radius, and is more than the minimum radius on the face or faces being offset, then