To cut crown molding straight at a 45 degree angle or right angle, generally a miter saw is used. However, in case a curved or rounded cut has to be made, a band saw has to be used. The easiest way to make a curved cut on the crown molding is to rip a straight molding piece into strips that are very thin, with the aid of a band saw. Take a curved template and bend the strips cut with the band saw around it, and apply glue to attach the strips of molding. On drying, you shall get a perfectly curved piece of crown molding.