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.

Excellent for challenging metals such as stainless steel and nickel alloys, these bits cut aggressively and evacuate chips quickly. The grooved flutes prevent clogs and improve coolant flow to dissipate heat that can damage the bit or your material. Bits are made of tough and wear-resistant cobalt steel.

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.

A diamond or diamondlike coating on these end mills makes them good for machining abrasive material, such as carbon fiber, fiberglass, and graphite. Made of solid carbide, these end mills are harder, stronger, and more wear resistant than high-speed steel and cobalt steel for the longest life and best finish on hard material. Their extreme hardness means they are brittle, so a highly rigid setup, such as a CNC machine, is necessary to prevent the end mill from breaking. They have a square end for milling square-bottomed slots, pockets, and edges. All are center cutting, allowing plunge cuts into a surface.

End mills with fewer flutes provide better chip clearance for high-volume, high-speed plunge, slotting, and roughing cuts; end mills with more flutes provide a finer finish and operate with less vibration when run at high speeds.

These end mills have a diamond or diamondlike coating for machining abrasive material, such as carbon fiber, fiberglass, and graphite. Made of solid carbide, they are harder, stronger, and more wear resistant than high-speed steel and cobalt steel for the longest life and best finish. Their extreme hardness means they are brittle, so a highly rigid setup, such as a CNC machine, is necessary to prevent the end mill from breaking. They have a ball end for milling rounded slots, slopes, and contours. All are center cutting, allowing plunge cuts into a surface.

End mills with fewer flutes provide better chip clearance for high-volume, high-speed plunge, slotting, and roughing cuts; end mills with more flutes provide a finer finish and operate with less vibration when run at high speeds.