These little things are brilliant for confined spaces get a pack of blades at the same time. They come in three shapes: straight, L-shaped and arched.

• Drill out sheared shafts.

• Drill a shaft to use a T-piece.

• Drill out a damaged thread.

• Cheap ones may bend or fracture.

• Can be sharpened to extend usable life.

• Always wear eye-protection

• Always wear hearing-protection

• Consider impact-protection