Originally Posted by
Warren Mickley
I was trained to sharpen freehand at a constant angle in 1962. By the time Sellers was starting a few years later, I had no trouble keeping an angle and had a nice reputation for my edges. I have sharpened chisels and plane irons without a grinder for my entire professional career as a hand tool only woodworker.
It has been a long time since I paid much attention to an exact angle, but when I measured everything a few years ago for a forum discussion, I found that everything was within a degree of 30. And this evening when I checked 8 chisels, they seemed right at 30. It is kind of surprising because I do not think the exact angle is that important.
Of you just taking light cuts with a chisel it doesn't matter if the bevel is flat or concave or convex, as long as the very tip is a reasonable angle. However there are chisel techniques where in addition to cutting at the tip, the chisel also acts as a wedge, pushing tissue with the bevel. Here the flat bevel works best because it forms a nice wedge. Mortising is one time a flat bevel works best.