Functional Design Using Design Accelerators - Autodesk Inventor 2010: No Experience Required - page 335

The Sweep Tool
An extrusion builds a body based on projecting a profi le so that it's normal
to its sketch plane. Sometimes you need that sketch to follow a path but you
don't need it to change shape, so a loft isn't appropriate. This is what the
Sweep tool is for.
Because the concept is similar to extrusion, the Sweep dialog box has a lot of
the same elements as Extrude. Other features are genuinely unique and demon-
strate some truly spectacular capabilities.
Type
The basic idea for having a profi le follow a path is powerful. But you can select
additional ways to defi ne the feature from the Type pull-down list:
Path The simplest and most common type, this option only needs a profi le and
a path to follow. The path doesn't need to intersect the profi le.
Path & Guide Rail Along with the profi le and a path to follow, this option
requires you to select a second rail that modifi es the transition of the profi le
along the selected path.
Path & Guide Surface Rather than using a basic sketch to modify the profi le
transition, this option takes into account the normal of a surface to control the
profi le. If you need to create a shape that transitions across a complex surface
yet maintains its position, this is your tool. Think about running a machine-
tool bit across a surface and keeping the bit normal to the face; this lets you
emulate that.