Page 251 - Mastering SolidWorks

|
identiFying when to use which tool 223

3. Select an axis (typically a construction line).
4. Set the end conditions.
5. Click OK.

Using Contour Selection
Like Extrude features, Revolve features can also use contour selection, and as with the Extrude
features, I recommend that you avoid using contours for production work.
Introducing Loft, Boundary, and Sweep
Sweep, loft, and boundary are known as interpolated features. This means that you can
create profiles for the feature at certain points, and the software interpolates the shape between
the profiles. You can use additional controls with loft, such as guide curves or centerlines, and
establish end conditions to help direct the shape. A loft with just two profiles is a straight-line
transition. If you have more than two profiles, the transition from one profile to another works
more like a spline.
Many users struggle when faced with the option to create a loft, boundary, or sweep. Some
overlap exists among the three features, but as you gain some experience, it becomes easier to
choose among them. Generally, if you can create the cross section of the feature by manipulating
the dimensions of a single sketch, a sweep might be the best feature. If the cross section changes
character or severely changes shape, loft or boundary may be best. If you need a very definite
shape at both ends and/or in the middle, loft and boundary are better choices because they
enable you to explicitly define the cross section at any point. However, if the outline is more
important than the cross section, you should choose a sweep. In addition, if the path between
ends is important, choose a sweep.
Both types of features are extremely powerful, but the sweep has a tendency to be fussier
about details, setup, and rules, although the loft and boundary can be surprisingly flexible. I am
not trying to dissuade you from using sweeps, because they are useful in many situations.
However, in my own modeling, I probably use about 10 lofts or boundary features for every
sweep. For example, although you would use a loft or combination of Loft features to create the
outer faces of a complex laundry detergent bottle, you would use the sweep to create a raised
border around the label area or the cap thread.
A good example of the interpolated nature of a loft is to put a circle on one plane and a
rectangle on an offset plane and then loft them together. This arrangement is shown in Figure 7.6.

Figure 7.6
interpolation
inside a loft