These headed liner drill bushings (HL) are used with removable slip-fixed (SF) bushings for guiding cutting tools and ensuring drilling accuracy. Headed liner bushings have an overhang that prevents them from being pushed through the jig and are typically used in applications where axial loads or vibration could alter the position of headless liners. Liner drill bushings are installed in the jig and then the removable bushings are inserted and removed as needed. The liner bushing can be installed with the head projecting above the fixture, or it can be countersunk so the head is flush with the fixture's surface. Bushings are used to guide drill bits, reamers, countersinks, and counterbores.
Bushings with standard wall thickness are used for most common applications.