After drilling, it is often encountered that the workpiece requires squeaking and back chamfering. The general machining process is to turn the workpiece after drilling and turn it over, milling it with a milling machine or boring with a boring machine. However, it is difficult or even impossible to process the workpiece shown in Figure 1. To this end, we have designed a tool for ruthenium processing, as shown in Figure 2. It consists of a knife bar 1, a blade 2 and a knife shaft 3. The diameter φA of the arbor shaft should be equal to the diameter of the workpiece. work