Boring bar
![A part's-eye view of a boring bar. It enters into an existing hole (drilled or cored), and the single-point cutters cut a cylindrical toolpath that is extremely accurate, being defined by the spindle's rotation and the linear motion of the Z-axis slide. In this case, the tool bits are of the brazed carbide type.](/Images/godic/202501/01/Boring_bar_0012437.jpg")
![Boring bar marked B](/Images/godic/202501/01/Machined_Holes.svg2438.png")
A boring bar is a tool used in metalworking and woodworking. Boring is a technique used in many aspects of building. Woodworkers have used boring as a form of drilling for centuries. In woodworking, the boring tool is static in size and used to form circular plunge cuts. In metalworking, boring is slightly different in that the hole that results need not be circular. In metal boring the tool can be plunged and dragged on the X or Y axes to create a slot or asymmetrical hole or channel, or it may be moved only in an up-and-down motion (on the Z axis) to create a perfect circular hole.