spotfacing tool (Figure H-110) is used when the back side of a hole is inaccessible to a standard spotfacer. The tool is fastened in a drill press chuck and put through the hole with the tool retracted. The tool swings out when the spindle is rotated and the spotface is then cut. The spindle is reversed to close and retract the tool from the hole. Some deburring tools operate on the same principle.