Drill Bit Basics
A drill bit is the detachable component of a drill used to cut a cylindrical hole. Drill bits can be used for different materials and are made of various materials in a multitude of sizes, depending on their application. Drill bit design, material, and finish are dependent upon their intended application. They each share some basic properties, but the tip and flute design is specifically made for the particular drilling application.
Drill Bit Types
Stubby Drill Bits
Stubby Drill Bits have a shorter overall length and shorter flute length. The shorter overall length makes the bit stiffer, and more resistant to deflection. Ideal for short run drilling applications.
Jobber Drill Bits
Jobber drill bits are straight shank drills suitable for general purpose applications. Jobber length bits are the most common and are considered standard length.
Long Length Drill Bits
Long Length drill bits have longer flutes and more overall length than standard jobber length drill bits of the same size. Their extra length allows them to create deep holes or drill into hard-to-reach workpieces.
S&D Drill Bits
S&D drill bits are large size drill bits with reduced shanks that are ideal for situations where a bit diameter is greater than the capacity of a drill chuck.
Step Drill Bits
Step drill bits can be used to drill a range of different sized holes with a single bit. Since each bit size drill holes less than 1/4″ deep, a step bit is mainly used for drilling thin material such as sheet metal.
Auger Drill Bits
Auger drill bits are bits used to drill holes into wood. They are commonly used for boring holes into bulkheads and general timber applications. These drill bits come with a spiral drill bit head which, when drilling, is designed to pull the bit into the wood so you do not have to apply excessive pressure. Auger bits are also effective in some fiberglass and plastic drilling applications.
Left Hand Drill Bits
Left Hand drill bits can be used to remove broken fasteners. Since right-handed bolts are loosened by turning to the left, the lefthanded drill bit loosens the right-handed bolts. This counterclockwise rotation in conjunction with material being removed from the center of the fastener, allows for loosening and removal in many cases.
Aircraft Extension Drill Bits
Aircraft Extension drill bits are similar in length to extra length bits, but they emphasize reach over cutting depth and have a shorter flute length (about the same as a jobber drill bit). This makes the bit stronger and less susceptible to bending and breaking.
Roto Brute Drill Bits
Brute drills feature Champion’s exclusive NOMO (Nitride on Margins Only) surface treatment. This surface treatment allows for better wear, and the ability to drill tougher metals than high speed steel alone.
Drill Bit Indexes
A drill index is a metal or plastic case that holds drill bits in an indexed order (by size), via a graduated series of holes. The standard index accommodates drill bits from 1/16" to 1/2" in diameter in 64th (imperial inch) increments.
Drill Bit Materials
Drill bits are made from different materials to suit their purpose. Using the right bit material enhances your efficiency. It also prevents you from losing money, purchasing a drill bit that cannot handle your project. While almost all bits are made from metal due to its toughness, the difference comes in the metal composition. The following are some common materials used in drill bits.
HSS Drill Bits (High Speed Steel)
High-speed steel (HSS) is one of the most commonly utilized materials in the manufacture of drill bits. It is suitable for drilling wood, plastic, and a variety of metals. High-speed steel bits are made from carbon steel with chromium and vanadium additives.
Nitro Drill Bits
Nitro drill bits are made from nitride-treated high-speed steel drill bits with a black and gold oxide finish. A heavy duty nitride treatment on high-speed steel (HSS) provides hardness for wear resistance, and the combined black and gold oxide finish resists corrosion and increases the hardness of the drill bit for additional wear resistance.
Cobalt Drill Bits
Cobalt drill bits are especially adept at drilling through stainless steel and other tough materials like hardened steel. Cobalt alloys have an exceptional ability to withstand heat and resistance. Sometimes, these drill bits consist of an alloy of cobalt and HSS. Such an alloy guarantees you a bit that can go through just about any surface.
Concrete Masonry Drill Bits
Carbide Tipped Drill Bits
Carbides are one of the strongest substances on the planet. Carbide tipped drill bits for hardened steel are commonly a straight flute design, having a steel body and carbide cutting tips. These bits do not yield as accurate a hole as a standard twist drill, but are well suited for applications drilling hard metals that are difficult to, or cannot be, drilled with cobalt or high speed steel.
Common Drill Angles
The two most common drill bit point angles are 118° and 135°. The difference between the two is the shape; a 118° bit is steeper, more pointed and has a smaller chisel. The 118° bit cuts more aggressively and is generally used for drilling into soft materials. Although it can puncture through steel, if used for this, the steeper cutting angle also will cause it to dull more quickly. A 135° bit typically is used for drilling into harder materials, because the pitch makes it easier to drill repeated holes into tougher material.