Taper Shank Twist Drills have conical shanks suitable for direct fitting into the tapered spindle holes of drill presses and other machines, lathe tailstocks and driving sleeves or sockets. This coupling is best described as a male cone within a female cone, and has self-locking and self-centering benefits. Taper shank drills are sized to the drill diameter as defined by the Morse taper shank standard. High Speed Steel drills are best for general purpose use on wood, plastic and softer metals, while stainless steel & exotic high-temperature alloys may require more expensive cobalt or carbide-tipped drills (see page 5 of our catalog for the Optimum Choice Drill Selection guide). For best results, use suitable lubricants/oils or coolant when recommended.