To make frame components 'C' and 'D' , follow the
procedure above, only make the first line 21" from the edge of the
2" strip, and measure back 11/16" for the second line.
Connect them diagonally and you should have your upper
beam angle. The finished beam components should measure:
A=39X3", B=23X3", C=21X2", and D=32 1/2" or close to that. A little bit
off doesn't matter much. I've yet to make two perfectly
identical frames.