SolidWorks 2011 Assemblies Bible - Matt Lombard [86]
Next, draw a circle concentric with the Origin, with the circumference on one corner of the rectangle. The sketch now looks like Figure 10.7.
When you have made this change, exit the sketch. The in-context references will not update until you exit the part and return to the assembly.
Just to get you prepared, what do you expect to see? Remember that one set of referenced edges was referenced by selecting a face, and the other set was referenced by selecting edges.
When you leave Edit Part mode and return to Edit Assembly mode, you will find that the outer lines have updated to the circle (because the face you selected is now circular instead of rectangular), but the edges you selected are still rectangular and display a warning symbol. This is because the edges referenced by those lines no longer exist. If you hover your mouse over one of the errors shown in Figure 10.8, it says, “Warning: Unable to offset one or more sketch entities.” You can avoid this error by using the same technique to select the inner lines as the outer lines (or just using the outer lines and making a Thin Feature).
Go ahead and fix this error by editing the sketch in the Virtual Part (box lid), deleting the lines causing the problem, and remaking them by offsetting from the selected face. Offset sketch relations cannot be repaired or edited in the way you need to repair the existing relations. In general, you should avoid using Delete as an editing technique, but there is no other way in SolidWorks to repair this kind of issue.
FIGURE 10.7
Replacing a rectangle with a circle
FIGURE 10.8
Responding to warnings when they occur
This demonstration points out some of the strengths and weaknesses of in-context modeling, but not all of them. The rest of the chapter will help you get a better idea of how to evaluate this technique for yourself.
Weighing the advantages of in-context modeling
The advantages of in-context modeling are obvious. In-context modeling is just an extension of parametric techniques to include parts in the context of an assembly. Making a change to one part and having all related parts update offers indisputable advantages. When it works correctly, all the parts of an assembly can be updated from a single change. Changes propagate all the way through to the part drawings.
Some users approach modeling haphazardly, where if it works, it's good enough. For some types of work, this is acceptable and really may be “good enough.” For example, it usually works when you create something that will never be changed or if you are working on initial concept models that will not be given to other users.
On the other hand, users who need to build models that will be reused frequently, changed often, or given to other users to work on must approach the decisions they make during modeling as if they were playing chess. Each decision has consequences. You rarely know exactly how things are going to turn out, but you need to prepare for the most likely contingencies, assessing potential risks along the way.
In-context modeling presents the same types of decisions. You can do it quickly with little planning or approach decisions methodically and with much consideration beforehand. The rest of the chapter shows the many tools that are associated with more advanced in-context techniques.
Anticipating problems with in-context modeling
The overall concept of in-context modeling is a great idea; the problems occur with the practical application of the technique and the management of the results through changes. In particular, the biggest problems seem to arise when in-context techniques are combined with other techniques. You must be very careful about things such as file management, assembly motion, multiple instances of parts in assemblies, configurations, and related issues when in-context references exist in your assembly.
Major potential