为防止钻头在扩孔或划埋头座时产生振动,可以把一小块砂布(砂面向下)覆盖在工件的扩孔处(图示),然后引进钻头钻透砂布。在这个过程中砂布随同钻头旋转把孔口磨出一个光洁的倒角,从而,改善了钻头在开始接触工件时的切削条件。然后取走砂布,就可以平稳地进行扩孔 To prevent the drill bit from vibrating when reaming or submerging the headstock, a small piece of emery cloth (sand side down) can be placed over the counterbore of the work piece (pictured) and then the drill bit can be drilled through the emery cloth. During this process, the abrasive cloth rotates with the bit to smooth the hole out of a smooth chamfer, thereby improving the cutting conditions of the bit at the beginning of contact with the workpiece. Then remove the emery cloth, you can smoothly reaming