Power tool drill bit model and size specification table? 

Understanding Power Tool Drill Bits: A Comprehensive Guide

Power tool drill bits are essential accessories for any professional tradesperson, DIY enthusiast, or homeowner. They are the cutting tools that, when attached to a power drill, create holes in various materials. The effectiveness of a drill bit depends on a combination of factors, including its design, the material it’s made from, its size, and how it’s used. Choosing the right bit for the job is crucial for achieving clean, precise holes, preventing damage to the workpiece, and ensuring the longevity of both the bit and the drill itself. The sheer variety of drill bits available on the market can be overwhelming, but they can be broadly categorized by the material they are designed to cut and their physical characteristics.

The most common types of drill bits are twist bits, which are recognizable by their helical flutes. Twist bits are the workhorses of the drilling world and are suitable for drilling into a wide range of materials, including wood, metal, and plastic. For specialized tasks, however, other bit designs are necessary. For example, spade bits and auger bits are specifically designed for drilling large holes in wood. Spade bits, also known as paddle bits, have a wide, flat blade with a point in the center for accurate positioning. They are excellent for quickly boring through thick wood but often leave a rough finish. Auger bits, on the other hand, feature a screw-like tip that pulls the bit into the wood, and their design allows them to clear chips effectively, resulting in cleaner, faster holes in softer woods. Masonry bits are another specialized category, distinguished by their carbide or tungsten carbide tips, which are hardened to withstand the high impact and abrasion of drilling into concrete, brick, and stone. These bits are typically used with a hammer drill, which combines a rotating motion with a hammering action to pulverize the material as it drills.

Drill bits are also differentiated by the material from which they are constructed. High-Speed Steel (HSS) is a very common material for twist bits and is suitable for drilling into soft metals, plastics, and wood. For increased durability and heat resistance, HSS bits are often coated with substances like titanium nitride (TiN), which gives them a distinctive gold color. TiN coating reduces friction and heat buildup, allowing the bit to stay sharper for longer and drill at higher speeds. Cobalt steel, often denoted as HSS-Co, is another superior material. It is an alloy of HSS with 5% to 8% cobalt, which significantly increases the bit’s hardness and heat resistance. Cobalt bits are excellent for drilling into hard metals like stainless steel and other tough alloys. For the hardest applications, such as drilling into cast iron or hardened steel, solid carbide bits are used. These are extremely hard and brittle and require a very rigid drilling setup to prevent them from breaking. Carbide is also the material of choice for the cutting tips on masonry bits, where it’s brazed onto a steel shank.

The sizing of drill bits is a critical aspect of their specification and varies by region and application. In the United States, drill bits are commonly sized in fractions of an inch, such as 1/4″, 3/8″, and 1/2″. These fractional sizes are the most common for general-purpose drilling. For more precise work, a numbered series (from No. 1 to No. 80) or a letter series (from A to Z) is used, with the numbers and letters corresponding to specific diameters. A No. 1 bit, for example, is 0.228 inches, while an “A” bit is 0.234 inches. Metric sizing, measured in millimeters (mm), is the standard in many parts of the world and is becoming increasingly common in North America. Metric bits are available in a wide range of sizes, often in increments of 0.5 mm or 1 mm. When choosing a bit, it’s essential to match the size to the fastener or anchor you intend to use. For instance, if you are installing a 1/4″ bolt, you would typically drill a hole slightly larger than 1/4″ to accommodate it, perhaps 17/64″ or 7 mm, depending on the desired fit.

Major Brands and Their Key Drill Bit Models

Many reputable brands manufacture high-quality drill bits, each with its own specialties and product lines. These companies invest heavily in material science and design to produce bits that meet the demanding needs of various industries. When you see a specific brand name, it often implies a certain level of quality and performance. Understanding the offerings of these major players can help you make an informed decision when purchasing drill bits for your specific needs.

Bosch is a global leader in power tools and accessories, known for its innovation and engineering quality. Their Daredevil spade bits are highly regarded for their aggressive, threaded tip that pulls the bit through the wood quickly and a contoured paddle design that removes chips efficiently, resulting in fast, clean holes. For masonry, Bosch offers a range of bits with carbide tips, including the BlueGranite series, which is known for its durability and fast drilling in concrete and brick. Their Impact Tough series of drill and driver bits is designed specifically for the high torque and impact of impact drivers, featuring a unique torsion zone that absorbs torque peaks to prevent breakage.

DeWalt is another top-tier brand, particularly popular in the construction industry. Their Black and Gold HSS drill bits are a staple, featuring a black oxide finish for corrosion resistance and a gold oxide finish on the flutes to prevent chip welding. The bits are also designed with a 135-degree split point, which helps to prevent “walking” on the workpiece and allows for faster drilling without the need for a pilot hole. For masonry, DeWalt’s Percussion bits with carbide tips are designed for hammer drills and are available in various lengths and diameters. DeWalt also offers an extensive line of impact-ready bits, including their Impact Ready FlexTorq series, which features a patented torsion zone that flexes to absorb shock and extends the bit’s life.

Milwaukee is a brand synonymous with heavy-duty performance and innovation. Their Thunderbolt Black Oxide drill bits are a popular choice for their durability and fast drilling. These bits feature a precision ground tip and a parabolic flute design that clears chips effectively. Milwaukee’s SHOCKWAVE line of bits is designed specifically for impact drivers, featuring a geometric compression zone that provides shock absorption and extends the life of the bit. Within the SHOCKWAVE line, they offer a wide variety of bits for different applications, including titanium-coated drill bits for metal, spade bits for wood, and masonry bits. Their SDS-PLUS and SDS-MAX series of bits are specifically designed for rotary hammer drills, with a unique shank design that locks into the chuck and provides superior power transfer for heavy-duty concrete drilling.

Irwin Industrial Tools is a brand with a long history of producing high-quality hand and power tool accessories. Their Cobalt M-35 drill bits are a testament to this, made from 5% cobalt steel for exceptional heat resistance and durability when drilling into hard metals like stainless steel. The bits are also designed with a split point tip for fast starts and reduced walking. For wood, Irwin’s Speedbor spade bits are a classic choice, featuring a patented micro-groove point and cutting edges that create cleaner holes and reduce splintering. Their Unibit step drill bits are a popular and versatile option, allowing users to drill multiple hole sizes with a single bit. The Unibit is excellent for thin materials like sheet metal and plastic, as it creates a clean, burr-free hole.

Makita offers a range of high-quality drill bits designed to work seamlessly with their power tools. Their Titanium Drill Bit Set is a popular choice for general-purpose drilling in metal, plastic, and wood. The titanium nitride coating provides a longer life and faster drilling speeds. For woodworking, Makita offers a variety of auger and spade bits, including their Hex Shank Auger Bits which are designed for fast, clean drilling in wood. The hex shank provides a secure grip in the drill chuck, preventing slippage under high torque. Makita also has a full line of SDS-PLUS and SDS-MAX bits for their rotary hammer drills, designed for maximum efficiency and durability in concrete and masonry.