My post was done at work, so it was kind of a mental exercise. Soon as I got home, I found an easier way to get the angle. Zero the cube on the base, then lay the FFG blade down so it is flat against the base (the handle will necessarily hang off the edge). Put cube on blade and measure angle. IF the grinds are symetrical, the angle of each side is the measured angle divided by 2. My Spydie super steel was about 5.2°, so about 2.5° per side.
Yes, for smaller blades, using the cube will be a problem. However, the human eye can do some amazing things. One of them is to find the center of a circle. The other is to see motion of the smallest amount out of the corner of the eye (watching out for Mr. Sabertooth…), and seeing that lines are askew, or not parallel (your picture frame and the ceiling/wall junction).
One should be able to, if you take your time, place the knife in the vise and see the symmetry in the gaps between blade and jaw. One should be able to look from behind down the edge and see that it is or is not canted to one side.
Just my additional thoughts.
