The cutting edge is flat and straight. It is mainly used to cut and smooth the concave and convex of the wood surface to make it smooth and traceless. Large models can also be used to chisel large ones. They have a sense of blockiness. They can be used properly, such as the brushwork effect of painting, which is vigorous, powerful, vivid and natural. The sharp angle of the flat knife can mark lines, and when the two knives intersect, the foot of the knife or the pattern can be removed.