I was thinning a knife tonight, and after getting it sharpened the damn thing would just not cut. It looked great, and had a nice geometry, but it bounced off of tomato skins half the time. I couldn't feel a burr, which is the usual culprit for me when things won't cut, though a few passes on .5 CrO/balso helped things a little. I decided to break out the ol' black marker to see if i was actually grinding what i thought i was grinding, and low and behold, I hadn't blended the bevels quite flat enough, and I was just barely, barely missing the edge at the angle I was going for. I hadn't used a marker on a knife in a long time, but I sure was glad that I had learned a reliable fundamental when I first started sharpening.