Chapter 7: Selecting Features
Tip
To select features for filleting, you must select them from the FeatureManager. The Selection Filter only filters
edges and faces for fillet selection. You can select loops in two ways: through the right-click Select Loop
option, or by selecting a face and Ctrl+selecting an edge on the face.
Another option for selecting edges in the Fillet command is the Select Through Faces option, which appears on
the Fillet Options panel. This option enables you to select edges that are hidden by the model. This can be a
useful option on a part with few hidden edges, or a detrimental option on a part where there are many edges
due to patterns, ribs, vents, or existing fillets. You can control a similar option globally for features other than
fillets by choosing Tools ➪ Options ➪ Display/Selection, Allow Selection In HLR [Hidden Lines Removed], and
Shaded Modes.n
Faces and Features selections are useful when you are creating fillets where you want the selections
to update. In Figure 7.31, the ribs that are intersecting the circular boss are also being filleted. If
the rib did not exist when the fillet was applied, but was added later and reordered so that it came
before the Fillet feature; then the fillet selection automatically considers the rib. If the fillet used
edge selection, this automatic selection updating would not have taken place.Tangent propagation .....................................................................................
By default, fillets have the Tangent Propagation option turned on. This is usually a good choice,
although there may be times when you want to experiment with turning it off. Tangent propaga-
tion simply means that if you select an edge to fillet, and this edge is tangent to other edges, then
the fillet will keep going along tangent edges until it forms a closed loop, the tangent edges stop, or
the fillet fails.If you deselect Tangent Propagation, but there are still tangent edges, you may see different results.
One possible result is that it could fail. One of the tricks with fillet features is to try to envision
what you are asking the software to do. For example, if one edge is filleted and the next edge is
not, then how is the fillet going to end? Figure 7.31 shows two of the potential results when fillets
are asked not to propagate. The fillet face may continue along its path until it runs off the part or
until the feature fails.Tip
This may sound counterintuitive, but sometimes when fillet features fail, it may be useful to deselect propaga-
tion and make the fillet in multiple features. There are times when creating two fillets like the one shown in
Figure 7.31 will work, and making the same geometry as a single feature will not. This may be due to geometry
problems where the sharp edges come together and are eliminated by the fillet. n
Best Practice
In general, fillets should be the last features that are applied to a model, particularly the small cosmetic or edge
break fillets. Larger fillets that contribute to the structure or overall shape of the part may be applied earlier.
Be careful of the rock-paper-scissors game that you inevitably are caught up in when modeling plastic parts
and deciding on the feature order of fillets, draft, and shell. Most fillets should come after draft, and large fil-
lets should come before the shell. Draft may come either before or after the shell, depending on the needs of
the area that you are dealing with on the part. In short, there is no single set of rules that you can consistently
apply and that works best in all situations. n