OP, you may have misread my e-mail. For all 90 degree corner cuts, the miter angle always stays at 45 degrees (left or right). You place the compound miter jig on the saw with the jig set for the crown you are using. The jig has textured surfaces so the material and jig stay securely on the saw. The crown sits in the jig with the bottom of the crown facing up. With the crown in the jig on the saw you just make a 45 degree miter cut and your angles come out perfect. My e-mail noted that when making cuts greater than 90 degrees you perform subtractions to determine miter angles. You never have to figure our any upside down and backward cuts.