There are two techniques can reduce the enormous resistance tool generated in the process of climbing. One is the use of a tortuous path to change the climbing angle, so that the tool close to the slope angle of the wall 45, rather than directly to the slope of the tool moving forward in Arch. In short, an angle climbing help reduce their effective slope, in order to avoid overloading the tool (Fig. 3). Another benefit of using 45 cutting is rounded to run from 0 to 90 in the course of every pass is only temporary contact, so that the tool can have some time to recover. After a few passes later, in parallel with these rounded cutting tool will increase the load may cause the tip of the temperature rise, weakening the strength of the tool.      In order to avoid the occurrence of overload the tool during cutting slope wall, another technique may be employed, i.e., the operation method using the level z, is processed in advance the slope walls. Then for milling on the part of the entire region tortuous, and the pre-processing of these sloping walls meant tool when confronted with these slope walls of their zag milling cutter can avoid unnecessary load.