I need some advice on cutting and sewing half and quarter triangles. Specifically for a double pinwheel and a square in a square blocks (not sure if those are the "technical" names of those blocks). Don't have very much info on the subject...one source said never to cut out sqaures and cut triangles out of those and another said you can do it. bj was kind enough to send me fabric for the quilt I want to make and I just don't want to screw up and waste that fabric.