Move the cursor to the upper middle portion of the screen and left click on the Look At icon as shown in Figure 56.

Figure 56

Move the cursor to the lower surface of the part causing the inside and outside edges to turn red and left click as shown in Figure 57.

Figure 57

After both edges turn red, left click once. Inventor will rotate the part providing a perpendicular view of the inside as shown in Figure 58.

Figure 58

Move the cursor over the same surface causing both the inside and outside lines to turn red. You may have to zoom in for Inventor to find both lines at the same time. Both lines must be red at the same time. After both lines are red at the same time, right click on the surface as shown in Figure 59. The surface will turn blue.

Figure 59

A pop up menu will appear. Left click on New Sketch as shown in Figure 60.

Figure 60

Inventor will start a new sketch on the selected surface. Your screen should look similar to Figure 61.

Figure 61

Move the cursor to the upper left portion of the screen and left click on Line as shown in Figure 62.

Figure 62

Move the cursor to the center of the part causing a green dot to appear and left click as shown in Figure 63.

Figure 63