Do I drill a hole first, then screw in bit? Or do I use the full end to bore the hole?

Here’s how to use it: Drill a pilot hole into the center of the broken screw or bolt using a drill bit of the size recommended on the extractor packaging (usually slightly smaller than the extractor’s diameter). Insert the screw extractor into the hole you just drilled. Turn the extractor counterclockwise (usually with a tap wrench or adjustable wrench). The spiral flutes will bite into the metal and help remove the broken screw. Do not use the full end of the extractor to bore the hole. The extractor is not designed for drilling; it is designed to grip and remove the screw after you have drilled a pilot hole.