There are three reasons for burr: first, the material itself (the quality is not as good as before), second, the tool (don't think that a new knife will do), and third, the method of changing carving into a right angle in the opposite direction in the software is to carve on the surface with a flat-bottomed sharp knife, and then change it into a straight knife (also called a column knife) after carving! Two tools are used to complete the machining. If some customers don't ask for the edge, they usually carve with a sharp knife and cut with a sharp knife to avoid the trouble of changing knives halfway. If the customer wants a straight edge, he must use two kinds of knives to carve and cut with a sharp knife. Nowadays, material suppliers generally sell knives. I hope I can help you, QQ: 4022 1833.