SolidWorks 2010 Bible

Chapter 32: Using Plastic Features and Mold Tools

A final termination situation I want to mention is one that can sometimes happen at curved edges.

If the extension of the rib cannot be contained by the model, the rib will fail. This is not always as

obvious a situation as you might think. When a non-horizontal rib intersects a curved edge, it usu-

ally forces you to fake something a little. Figure 32.10 shows an example of why this is.

FIGURE 32.10

The part wall does not terminate the rib.

The reason for the error shown in Figure 32.10 is that even though the rib sketch intersects the

edge of the part, the width of the top of the rib would go past the edge and not intersect anything.

One way to deal with this is to make the sketch intersect the part a little closer to the center of the

part from the edge. Another way would be to put a short vertical line at the end of the rib.

Using thin features

Thin feature extrusions are sometimes used in place of ribs. Thin features do not have all the spe-

cialized options available with the Rib feature, but they do offer simplicity as the main attraction.

Thin features can substitute for Rib features when the rib is a stand-alone rib that doesn’t touch the

side walls of the part. They can be used to sketch and extrude from the bottom of the rib or from

the top. When extruding a thin feature with draft, the end faces get drafted as well, which might

cause a problem if you are trying to attach the rib to a wall. Extruding a thin feature down from the

top of the rib can replace a plan view rib, but it will not enable you to break those pesky sketch

rules that the Rib feature simply dispenses with.