A clamp pin tool holder for clamping an insert in a tool holder includes a bore for receiving a clamp pin and a bore for receiving a lock screw. The clamp pin includes a cam portion with angled surfaces. The lock screw is rotatably mounted to the bore of the tool holder and includes angled surfaces for engaging the angled surfaces of the clamp pin. When the lock screw is rotated in one direction, one angled surface on the lock screw and one angled surface on the clamp pin engage each other an acts as a conical wedge to cause the clamp pin to move relative to the lock screw. When the lock screw is rotated in the opposite direction, another angled surface on the lock screw engages a different angled surface on the clamp pin in a similar manner to cause the clamp pin to move in an opposite direction.