I’m happy with both finishes but the finish left by the negative rake fly cutter is fabulous, almost mirror like, the positive rake fly cutter left a more matte finish. I think the lines are visible because the insert has a small radius (ie more pointy).
Not at all a apples-to-apples comparison, I’m prepping some steel (both unknown alloys) for a project and used best sized fly cutter on each.
Here is the 5″ fly cutter in action (the 2.5″ fly cutter video is in the previous post):
ZK Project Notebook 