Commonly known as the "monk head", "butterfly chisel", the edge of a circular arc, is a knife between the knife and the knife between the light with a knife, sub-arc and oblique arc two. After cutting the tool with a blunt (with the edge of the blade was a white line, commonly known as bald), first in the rough stone (or Whetstone) on the grinding edge, coarse grinding stone particle size not too much, the surface should be smooth, Grinding to the edge of the office, and then fine grinding on the fine grinding stone, when the edge of the grinding stone in the fine grinding of the back edge, the knife turned over the steel surface flat paste fine stone back flat drag a few Back a few), grinding off the edge of the volume crumbs.