Abstract: A centering tool for use in a chuck or collet of a drill press or milling machine enables positioning of a round or cylindrical workpiece such that its axis is precisely positioned to intersect the axis of rotation of the machine. The tool enables the efficient drilling of a hole through a cylindrical bar, perpendicular to the axis of the bar, for example. A cylindrical shank of the tool is adapted for insertion into the chuck or collet, and a centering body affixed to the shank has a generally V-shaped centering notch symmetrical about the shank's axis and having an apex line crossing the shank's axis.