With flutes that spiral in the opposite direction of other bits, these are primarily used to remove stripped screws. Choose a bit that’s slightly smaller than the diameter of the screw’s head. Set your power tool to rotate in reverse. Slowly drill in the center of the screw head, maintaining constant pressure. As the bit penetrates, it will catch onto the screw and reverse it out of the hole. If the screw is badly stripped, you might need to punch a starter hole. Also known as reverse-flute bits. High-speed steel is the versatile choice for drilling most metals.

With flutes that lift chips out of the hole, you don't have to stop drilling to clear these bits manually. They improve coolant flow to dissipate heat and prevent clogs that can damage the bit and ruin the hole. High-speed steel is good for general purpose drilling in most metals.

These bits combine the toughness and wear resistance of cobalt with short flutes for rigidity. The shallow drilling depth makes them less likely to wobble than other bits of the same length, so they stay centered and drill straighter. Cobalt lasts at least twice as long as high-speed steel. It can also run up to 25% faster at higher temperatures without damaging the bit on hard materials such as nickel.