Moving into the Assembly World - Autodesk Inventor 2010: No Experience Required - page 125

The Corner Round Tool
This tool is very simple. It places rounds on only the edges that can be rounded
while cutting the fl at pattern. The Fillet tool in the Model tab puts a rounded edge
on just about anything; but this is a sheet metal-specifi c tool. It has two modes.
Corner mode allows you to select individual edges — although not all edges are
acceptable, as mentioned. You can deselect an edge by holding Ctrl and picking
again. Feature mode rounds any edge on a selected feature. Let's use this tool:
1. Select the Corner Round tool from the Modify panel.
2. Switch the Mode to Feature, and leave the Radius set to .25.
3. Move over the face you created. It highlights. Pick it when it does;
the open corners preview, showing that they will be rounded,
and the dialog indicates that two edges are selected.
4. Click OK to add the rounds to the corner. See Figure 3.13.
FIGURE 3.13 The face with rounded corners