Drills

A drill blank is an unfinished cylindrical rod of tool steel, the starting material for making twist drill bits. It lacks the characteristic helical flutes and a finished shank. Drill manufacturers use these blanks to efficiently produce drills with specific dimensions, point geometries, and material qualities.

A drill mill is a versatile cutting tool that acts like both a drill bit (for plunging holes) and an end mill (for side cutting of slots and contours). This dual functionality reduces tool changes, improves accuracy, and simplifies machining by allowing multiple operations with a single tool, especially in CNC machines.

A jobber drill is the most common, general-purpose twist drill bit in manufacturing. Its intermediate length (flute length 9-14 times the diameter) provides a good balance of drilling depth and rigidity for drilling various materials like steel, metal, plastic, and wood. It typically has a straight shank, two spiral flutes for chip removal, and often a 118-degree point angle. Made primarily of HSS, it's a versatile and widely used drill bit.

A reduced shank drill has a shank diameter smaller than its cutting diameter. This design allows larger drill bits to be used in drill chucks with smaller capacities, effectively expanding the drilling range of a machine.

A screw machine drill is a short, rigid twist drill bit designed for accuracy and durability in automated machining like screw machines and CNCs. Its stubby length minimizes deflection, leading to more precise holes, especially in high-speed, repetitive operations. While sacrificing drilling depth, it offers improved control and is suitable for various materials.

A spotting drill is a short, stiff drill bit used to create a precise starting indentation for other drills. This prevents the final drill from wandering, ensuring accurate hole placement, especially on uneven surfaces. It often has a wider point angle (60, 90, or 120) and can sometimes create a starting chamfer. Using a spotting drill improves hole quality and extends the life of subsequent drill bits.

A taper length drill is a twist drill with longer flutes and overall length than a standard jobber drill, allowing for deeper hole drilling in one pass. The name historically refers to its tapered core, which provides added strength for the extended length. It's used for drilling deeper holes than jobber drills but not as deep as extra-long drills.

A taper shank drill has a cone-shaped shank that fits directly into a machine spindle (like a drill press) without a chuck. This provides a strong, rigid connection for high torque and accurate drilling of larger diameter holes, typically those above 1/2". Many also have a tang for added drive and easier removal.