A machine tool a slide attached on a base and moveable along an X-axis, a carriage attached onto the slide and moveable along a Y-axis, a follower rotatably mounted on the carriage, a sliding member attached on the follower and moveable along a Z-axis, a carrier rotatably attached to the sliding member, and a tool holder mounted on the carrier and rotatable relative to the carrier to selected angular positions for supporting a shaft, and a barrel slidably received in the shaft for supporting a tool member. The barrel includes a noncircular chamber for engaging with a noncircular shank of the tool member and for preventing the shank of the tool member from rotating relative to the barrel and the shaft.