bevel angle is 25 degrees. I tried putting the chisel in the middle and squaring it up. It worked ok but took a long time. I had to work the high side by spending more time grinding it. I notices that my wheel now has a high spot a little off centere of the middle. I had trued it up yesterday for another tool. What causes the grinding wheel to be high in the middle. I seem to have to true it quite often. Also I have a hard time getting rid of the streaks with the rough side of the grading wheel.