To use a miter cut chart such as the chart for cutting crown molding at DeWalt.com, first measure the angle of the corner between two walls. Find the angle on the chart in the first column on the left to see which miter and bevel settings are needed for the miter saw. The saw settings differ depending on the crown molding's angles, so the chart contains settings for cutting both styles of molding.
A similar chart is available at ExtremeHowTo.com. Use the same row on the chart to calculate the mating cut. If it is difficult to visualize the cuts, make a set of templates for horizontal and vertical turns. The templates help when setting up the saw and determining the trim placement. Use a compound miter saw or regular miter saw to make the cuts. It is important to test all of the cuts on scrap material before cutting the molding.
A compound miter saw calculator is available at Jansson.us. The calculator's different sections are used to calculate cut angles for corners, boxes and pyramids. For boxes, enter the number of sides and the side angle. The calculator displays the necessary blade tilt and miter angle to use on the saw, along with the dihedral angle. For pyramids, enter the number of sides, the base radius and the height. The calculator displays the blade angles along with the base side, slope and dihedral angle.