box blade cutting angle

[dtjim]

im building a 5 ft box blade blade for general use with my 9N, can anyone out there tell me what angle the the cutting edge is at on a store bought one and also how far below the box the cutting edge extends. I was thinking of making it 45 deg but i remember reading on here that it should be 30 deg but it doesnt seem right to me

 

[Sfrankland]

The cutting angle on most blades is around 70 degrees.