Advanced Part Modeling Features - Inventor 2013 and Inventor LT 2013 Essentials - page 169

Adding a Draft Angle
When creating an extrusion, sweep, and a few other features, you can include
a draft angle, referred to in their dialog boxes as a Taper value. Sometimes it is
best to add draft after the fact. With the bottle, for example, you need to include
draft on a face that couldn't be added at the time the main feature was created.
For that purpose, you can use the Draft tool.
1. Make certain that the 2013 Essentials project file is active, and then
open c07-11.ipt from the Parts\Chapter​7 folder.
2. Be sure that you orbit the part to see the green face on the bottom.
3. Start the Face Draft tool on the Modify panel of the Model tab.
The Face Draft dialog box will prompt you with an icon to select
the pull direction. The pull direction is a face or plane around which
the draft angle pivots.
4. Select the yellow face on the part to use it for the pull direction.
5. Select the side face of the recessed extrusion near the yellow face, and
set the angle to 15 degrees, as shown in Figure 7.20.
Once selected, the preview of the face raft should show the bottom
edge of the face moving into the open space. If it doesn't, select the
Flip Pull Direction icon to correct it.
6. Click OK to add the draft to the part.
FIGURE 7.20 Like some other features, draft provides
an arrow you can drag to change its angle.
You can also place the draft based on a plane or a sketch. The plane can even
be set away from the faces to be drafted.