SolidWorks 2011 Parts Bible - Matt Lombard [267]
The Extend Surface feature functions much in the same way that the Extend function works in sketches. Figure 20.11 shows the PropertyManager interface and an example of the feature at work.
The only item here that requires explanation is the Extension Type panel. The Same surface option means that the extended surface will simply be extrapolated in the selected direction. A Planar Surface is the easiest to extend because it can go on indefinitely without running into problems. A cylindrical surface can only be extended until it runs into itself. Complex lofted or Swept Surfaces are often difficult to extend. Extrapolating a complex surface is not easy to do and often results in self-intersecting faces, which cause the feature to fail.
When the Same surface setting works, it creates a nice result because it does not create an edge where the extension begins; it smoothly extends the existing face.
FIGURE 20.11
The Extend Surface PropertyManager
The Linear option is more reliable than the Same surface option because it starts tangent to the existing surface and keeps going in that direction, working much like a Ruled surface, which is covered later in this chapter. It does not rely on extending the existing surface. This option creates an edge at the starting point of the new geometry.
Using Trim Surface
The Trim Surface feature is described briefly earlier in this chapter, but it warrants a more complete description here. Surfaces can be trimmed by three different types of entities:
• Sketches
• Planes
• Other surfaces
When you use surface bodies to trim one another, you must select one of two options: Standard or Mutual Trim. The Standard option causes one surface to act as the Trim tool and the other surface to be trimmed by the Trim tool. When you select the Mutual Trim option, both surfaces act as the Trim tool, and both surfaces are trimmed.
For an example of trimmed surfaces, open the mouse example from Chapter 19 and step through the tree. This shows examples of a couple of types of trimmed surfaces, as well as extended surfaces and others.
Many people overlook the ability to trim a surface with a plane, which can be very handy sometimes. Planes are infinite, which means you have less to worry about when it comes to changes that affect features rebuilding correctly.
Finally, trimming with 2D sketches is well known, but trimming with 3D sketches is less known. There is a 3D sketch tool called Spline on Surface that enables you to draw a spline directly on any surface body. An option exists in the Trim Surface PropertyManager to trim a surface with this type of sketch. This is very useful in many situations if you can remember that it is available.
Using Fill Surface
The Fill Surface is one of my favorite tools in SolidWorks. I often refer to it as the “magic wand” because it is sometimes amazing what it can do. It is alternately referred to by the SolidWorks interface and documentation as either Fill or Filled, depending on where the reference is made. You will find it listed as both in the SolidWorks interface.
The Fill Surface is intended to fill in gaps in surface bodies. It can do this either smoothly or by leaving sharp corners. You can use constraint curves to drive the shape of the fill between the existing boundaries. It can even knit a surface body together into a solid, all-in-one step. Beyond this, you can use the Fill Surface directly on solid models and integrate it directly into the solid automatically (much like the Replace Face function, which is described later in this chapter).
Several rather complex examples of the Fill Surface are found in the bike frame example. One of these fills is shown in Figure 20.12.
FIGURE 20.12
The Fill Surface PropertyManager and the results of applying it
The first thing you should notice about the Fill Surface is that it is creating an oversized, four-sided patch and trimming it to fit into the available space. This is one of the reasons why I consider this to be such a magical tool. The four-sided patch I referred to earlier