Love your piano keys, they look great. As to the setting triangles, I just sort of measured how big they needed to be on the one side, adding a bit for the seam allowence, and figured how big a square woudl be. Real scientific, huh? I know somewhere on the web there will be a table telling you how big to make them, but sorry, I can't help there. I'm a seat-of-the-pants kind of quilter, and sometimes it works, sometimes not. LOL