I have been installing wainscoting in my hallway by placing a chair rail at approx. 31"(including the stairway). I have made square frames and installed them below the rail. I now want to install these frames on the stairway with the top and bottom sides being paralell to the rail and the left and right sides being vertical. I'm having difficulty mitering the corners of the frames because I need more than 60 dgrees and that's all my table saw allows.

Help!!