Part II: Building Intelligence into Your Parts
Working with the Revolve feature
Like all other features, revolve features have some rules that you must observe when choosing
sketches to create a revolve:
l Draw only half of the revolve profile. (Draw the section to one side of the centerline.)l (^) The profile must not cross the centerline.
l The profile must not touch the centerline at a single point. It can touch along a line,
but not at a point. Revolving a sketch that touched the centerline at a single point would
create a point of zero thickness in the part.
You can use any type of line or model edge for the centerline, not just the centerline/construction
line type.
End conditions ..............................................................................................
There are three Revolve end conditions:l One-Direction. The revolve angle is driven in a single direction.l (^) Two-Direction. The revolve angle can be driven in two independent directions.
l Mid-Plane. The revolve angle is divided equally in opposite directions.
There is no equivalent for Up to Vertex, Up to Next, Up to Surface, or Up to Body with the
Revolve feature.
Contour selection ..........................................................................................
Like extrude features, revolve features can also use contour selection; and as with the extrude fea-
tures, I recommend that you avoid using contours for production work.Introducing Loft
A loft is what is known as an interpolated feature. That means that you can create profiles for the
feature at certain points, and the software will interpolate 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 or a sweep. Some overlap exists
between the two features, but as you gain some experience, it becomes easier to choose between
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, a loft may be best. If you need a very definite shape at both ends and/or in