Chapter 16: Modeling in Context
If you are considering using the Break Relations tool, then you should either reconsider and use
Lock Relations instead or simply remove all the in-context relations altogether.
Other types of in-context references are not as easy to remove as sketch relations. When you see
the External Reference symbol on a sketch, it could be the sketch relations or it could be the sketch
plane that was in-context. In order to remove the reference from an in-context sketch plane, you
must redefine the plane locally in the part.
You should also not forget end conditions such as Up To Surface, Offset From Surface, or even
From Surface. If an external reference symbol remains on a feature, you can use the Parent/Child
option on the RMB menu to locate it. Remember that using an edge or vertex for a plane definition
can cause an in-context relation.
Should you use mating or in-context?
In-context is initially so fast and easy to use that it can be addictive, but you need to think before
you use it because of the speed and file management implications these relations will have later on
in your design process.
Communicating design intent
If someone else needs to use your model after you are done with it and possibly edit it, then you
should leave some clues to help this person understand how the model works, and how it is best
changed. For example, you can use descriptive feature and sketch names, comments that are asso-
ciated with features, the Design Binder to add documentation, and the Design Journal to write
notes. You can even put HTML (Hypertext Markup Language) links in notes that display in the
graphics window.
In-context design intent may not always be obvious, and an impatient user may find it more expe-
dient to delete the in-context references and replace them with either local relations or no relations
at all. The more you document your intent, the more likely others will be to follow it.
Using Other Types of External References
The external reference symbol (- >) indicates in-context features that have been created in the con-
text of an assembly, but it also indicates three other types of external references —Inserted parts,
split parts, and mirrored parts.
Understanding inserted parts
I discuss inserted parts to some extent in Chapter 10, and in more detail in Chapter 28. In the
past, inserted parts have also been called base parts and derived parts, and some users still use
those names.