Draw a line on the parts that need to be processed, first punch a positioning hole with the sample in the position that needs to be drilled, the drill bit is aligned with the small pit with a little force to press the drill, the drill switch is pressed to make the drill turn and stop, so that the center of the positioning pit will not run, after the drilling has a depth of 2MM, you can press the drill switch for a long time to drill, but still can not force too much, the standard is.