Need Help Cutting C-notch on 59

[Fat Mike]

I need help cutting the c-notch. I am not sure what anlge to cut the 2x6 tubing at. I was told to cut it at 35* but when I went to put the pieces together nothing came out right. A friend of mine then cut some for me and all the angles came out correct. I measured the angle and it was at 55* thou. Where did I mess up? I need to know where to set my chop saw at (harbor frieght style) for the correct angle I am looking for? My chop saw goes from 0-45*. I was messing with some cardboard and got the correct angle I was looking for but it was a 60* angle. How do I set that On my chop saw?