Part III: Working with Assemblies
External references
Notice the “->” symbol after the Equations folder in the Assembly FeatureManager. This means that
there is an external or in-context reference. An external reference means that an aspect of the part
is dependent upon something outside of the part. This has file management implications because
you must maintain the names of the files so that they always recognize the other file involved in
the external relation. In-context means that one part has a relation to another part in positions
determined by an assembly. So in this case, the in-context external reference can only be solved if
the original part, the referenced part, and the assembly where the relationship was created are all
open at the same time.Cross-Reference
In-context references are discussed in depth in Chapter 16. n
When one part drives another part in this way, the assembly must also be open to drive the
relationship. If just the two parts are open individually, then changing the driving part does not
update the driven part; because the relationship was created in the context of the assembly, the
assembly must also be open to facilitate the change.Link values and global variables
Link values and global variables also work in assemblies, but they do not work between parts.
Local assembly sketches can use these functions, and the parts can use them when edited in the
context of the assembly, but they cannot cross any document barriers (links must remain within a
single document).Renaming
Equations update with new part names regardless of how the part is renamed. Names of
subassemblies also update when assembly files are renamed. This includes renaming a document
using the Save As command, using SolidWorks Explorer, or using Windows Explorer. It also
includes redirecting the assembly to the new part name, as well as renaming the assembly using
each of these techniques. If the assembly can find the part and recognizes the part as the one
that it is looking for, then the equation will work.Some of the methods named previously for renaming parts are not recommended; for testing
purposes I specifically tried to break the relationships in the equations by using them. SolidWorks
Explorer and the Save As methods can be effective when used properly. References between files
are a different issue altogether from an equation’s references to local file names.Recommendations
While assembly equations are certainly a valid way to control part sizes, I would recommend using
assembly or part configurations, possibly with design tables, to accomplish something similar.
Equations and configurations do not mix well because the two methods compete to control the
dimensions. I recommend configurations with design tables over equations.