Learning the Essentials of Part Modeling - Inventor 2013 and Inventor LT 2013 Essentials - page 79

FIGURE 3.16 Adding new geometry to an existing
sketch
Now, you can create more sketch geometry that is based on the center of the
part. This is why it can be very useful to think about centering a part on the
origin planes.
1. Continue using the drawing from the previous exercise or make
certain that the 2013 Essentials project file is active, and then open
c03-07.ipt from the Parts\Chapter​3 folder.
2. Expand the Origin folder in the browser.
3. Click the XY plane. This will highlight the plane in the Design window
and present you with the Create Sketch icon.
4. Click the icon to start a new sketch on that plane.
5. The center point of the part will automatically project into the new
sketch, but it will be difficult to see it from the front.
6. Right-click in the Design window, and select Slice Graphics (or press
the F7 key) to remove some of the part to expose the new sketch. You
can also pick the Slice Graphics icon in the status bar.
7. Start a new line at the part's center point, going straight up click
roughly at 30 mm.
8. Move your mouse to the endpoint of the line you just created, click,
and drag an arc tangent to the last line, as shown in Figure 3.17.