Working with Sheet Metal Parts - Inventor 2013 and Inventor LT 2013 Essentials - page 223

8. Click the Bend tab, and change Relief Shape to Tear and Bend Radius
to 2 mm, as shown in Figure 10.3.
9. Click the Corner tab. Change 2 Bend Intersection Relief Shape to
Linear Weld.
10. Change the Relief Shape value for 3 Bend Intersection to Full Round.
See Figure 10.4.
11. Click Save, and then double-click the Aluminum 3 mm rule (on the
left) to make it active.
FIGURE 10.3 Use the Bend tab to control the radius of the
bend and how edges will intersect with the sheet.
FIGURE 10.4 The Corner tab regulates how material will
be removed from the corner or whether it will be left in.