Winston
> You can get the effective cutting angle, before and/or after, by running the chisel bevel down across your benchtop, and check the angle where it first begins to dig in. Do this beside a vertical surface like a block of 2x4, mark the angle where the chisel begins to bite, and check that angle with your own protractor.

I gave it a try. On a very smooth planed piece of white pine, I got anywhere between about 35 and 42 degrees. It's hard to get a consistent reading. The angle where it first digs in is sensitive to amount of downward pressure. If the chisel gets rotated (along the long axis) a bit in either direction, the corners dig in, and then if I try to stabilize it by putting a little bit of pressure near the tip (as if sharpening freehand), that makes it want to dig in at a lower angle than it would otherwise. As I raise the angle, there's also a range of angles where it stutters but doesn't quite catch. So... in short, in order to get a consistent value, I think the variables would have to be controlled much better than I'm able to do.