What are the specifications and sizes of hollow drill bits?

Specifications and Sizes of Hollow Drill Bits

Hollow drill bits, also commonly referred to as core drill bits, annular cutters, or hollow-core bits, are specialized cutting tools designed to remove cylindrical sections of material, leaving behind a clean and precise hole with minimal waste. Unlike traditional twist drill bits that remove all the material within the diameter of the hole, hollow drill bits cut only the outer edge of the circle, which makes them faster, more efficient, and capable of producing larger diameter holes with less effort. These bits are widely used in construction, metalworking, woodworking, and tile or glass cutting. To fully understand the specifications and sizes of hollow drill bits, it is important to examine their dimensional ranges, shank types, materials, cutting edge design, cooling requirements, brand-specific variations, and applications across industries. Hollow drill bits come in an extensive variety of sizes and are manufactured by leading brands such as Bosch, Hilti, Makita, DeWalt, Milwaukee, Starrett, Fein, and others. Each brand offers multiple product lines, with slight variations in material composition, intended use, and dimensional precision.

General Specifications of Hollow Drill Bits

When describing the specifications of hollow drill bits, several technical aspects must be considered, such as diameter range, cutting depth, shank type, coating, material composition, and compatibility with different drilling machines. The diameter of hollow drill bits typically ranges from small precision bits of 6 mm or 1/4 inch up to very large industrial core cutters exceeding 200 mm (8 inches) in diameter. Standard diameters often include 12 mm, 16 mm, 22 mm, 25 mm, 32 mm, 38 mm, 50 mm, 76 mm, and 100 mm, depending on the manufacturer and application. In terms of cutting depth, many hollow drill bits are available in lengths ranging from 30 mm to 150 mm, with specialized long-reach core drill bits extending up to 300 mm for deeper drilling applications. Shank types also vary: the most common are Weldon shank (19 mm or 32 mm), SDS-plus shank, SDS-max shank, hex shank, and cylindrical straight shanks. For example, annular cutters for magnetic drills often use Weldon shanks, while masonry core bits for rotary hammers often employ SDS-plus or SDS-max shanks. Material composition is another critical specification. High-speed steel (HSS), cobalt-alloyed HSS, carbide-tipped steel, diamond-tipped segments, and polycrystalline diamond (PCD) are among the most common materials. These choices allow hollow drill bits to perform well in drilling through concrete, reinforced concrete, tiles, granite, marble, stainless steel, aluminum, mild steel, and even glass. Many bits are also treated with surface coatings such as titanium nitride (TiN), titanium aluminum nitride (TiAlN), or black oxide to increase durability and reduce heat.

Sizes of Hollow Drill Bits in Metalworking

In the field of metalworking, hollow drill bits are most commonly referred to as annular cutters. Annular cutters are primarily used with magnetic drill presses and can cut through structural steel, pipes, and sheet metal efficiently. Typical diameters for annular cutters range from 12 mm to 100 mm (1/2 inch to 4 inches), with cutting depths of 30 mm, 55 mm, 75 mm, and 100 mm depending on the product series. For instance, Fein offers its HSS Annular Cutter line with Weldon shanks in diameters ranging from 12 mm to 65 mm, while Starrett’s VersaDrive annular cutters extend up to 100 mm. DeWalt offers 19 mm Weldon shank annular cutters with cutting depths of 55 mm and 110 mm. Milwaukee’s annular cutters range from 7/16 inch to 2 inches, with cutting depths up to 2 inches. These bits are specifically engineered to deliver burr-free holes with smooth finishes, which is a key requirement in metal fabrication and structural steel applications. Some advanced annular cutters incorporate replaceable carbide inserts, allowing for reusability and cost efficiency.

Sizes of Hollow Drill Bits in Masonry and Concrete

In construction and masonry, hollow drill bits are often known as core drill bits. They are widely used for drilling through concrete, reinforced concrete, masonry walls, and stone. Sizes for masonry hollow drill bits typically range from 16 mm to over 200 mm in diameter. Common sizes include 25 mm, 32 mm, 52 mm, 68 mm (a very standard size for electrical socket installation), 82 mm, and 110 mm, with extended sizes of 150 mm and even 200 mm for large utility openings. Hilti is one of the most recognized brands in this category, offering their TE-YX and DD core bits in a wide range of diameters and cutting depths. Bosch’s SDS-plus and SDS-max hollow drill bits are popular for creating dust-free holes in concrete, ranging from 12 mm to 68 mm. Makita provides diamond core drill bits for reinforced concrete with diameters between 32 mm and 152 mm. These masonry hollow drill bits often include diamond segments or carbide tips for superior penetration of hard aggregates and rebar. Cutting depths usually range between 50 mm and 150 mm for handheld rotary hammers and can exceed 300 mm for specialized drilling rigs used in utility work.

Sizes of Hollow Drill Bits in Woodworking

In woodworking, hollow drill bits are often designed for cutting large-diameter holes for furniture making, cabinetry, and flooring installations. These bits are commonly called hole saws, which are technically a type of hollow drill bit. Hole saw sizes typically range from as small as 6 mm to as large as 152 mm. Standard woodworking hole saw kits from brands such as Milwaukee, DeWalt, and Makita often include sizes from 19 mm (3/4 inch) up to 64 mm (2 1/2 inches). Starrett offers professional hole saw sets extending to 152 mm (6 inches). The cutting depth for woodworking hollow bits usually ranges from 25 mm to 50 mm, depending on the model. Some woodworking-specific hollow bits are equipped with carbide teeth for cutting through engineered wood products such as MDF, plywood, or laminate flooring, while others are optimized for clean cuts in softwood and hardwood. Adjustable hole saw systems are also available, where the cutting diameter can be customized within a given range, offering flexibility in woodworking applications.

Sizes of Hollow Drill Bits for Glass, Tile, and Ceramics

When drilling through fragile materials such as glass, porcelain, and ceramic tiles, hollow diamond drill bits are the most suitable. These bits are generally small to medium in diameter, ranging from 6 mm up to 75 mm. Typical household applications include 6 mm, 8 mm, 10 mm, and 12 mm bits for plumbing and hardware installations, while larger sizes such as 50 mm and 68 mm are used for bathroom fixtures or pipe access points. Bosch offers diamond hole saws ranging from 5 mm to 75 mm for tiles and glass. DeWalt’s Diamond Grit Hole Saws are available from 19 mm to 83 mm. These hollow drill bits usually feature a thin diamond-coated rim to minimize cracking and chipping, and they require constant water cooling to prevent overheating. Cutting depths are typically around 25 mm to 50 mm, since glass and tile surfaces are relatively thin compared to concrete or metal.

Brand-Specific Examples of Hollow Drill Bits

Bosch produces a wide range of hollow drill bits, such as the Bosch Diamond Core Drill Bits for tiles (sizes from 5 mm to 75 mm), Bosch SDS-max Hollow Dust Extraction Drill Bits (16 mm to 52 mm), and Bosch Progressor Hole Saws (18 mm to 152 mm). Hilti manufactures TE-YX Hollow Drill Bits with dust removal functionality, available in sizes 12 mm to 52 mm, as well as DD-B Diamond Core Bits ranging up to 202 mm. DeWalt’s core drill bits include the Extreme Diamond Core Bits (22 mm to 152 mm) and Weldon-shank Annular Cutters (12 mm to 60 mm). Milwaukee offers Hole Dozer Bi-Metal Hole Saws ranging from 14 mm to 152 mm and Carbide Annular Cutters in diameters from 7/16 inch to 2 inches. Starrett offers Diamond Grit Hole Saws (6 mm to 152 mm) and HSS Annular Cutters (12 mm to 100 mm). Fein, known for magnetic drills, provides annular cutters in sizes ranging from 12 mm to 65 mm with cutting depths up to 100 mm. Makita also has diamond core drill bits for masonry (32 mm to 152 mm) and bi-metal hole saws (19 mm to 152 mm).

Applications of Different Sizes of Hollow Drill Bits

The selection of hollow drill bit size depends largely on the application. For electrical installations, sizes such as 20 mm, 25 mm, and 68 mm are common for running conduits and installing sockets. For plumbing, larger diameters such as 82 mm, 110 mm, and 152 mm are used to pass pipes through concrete walls or floors. In metal fabrication, annular cutters between 12 mm and 50 mm are often used to drill bolt holes in structural beams. Woodworkers may choose hole saws from 25 mm to 76 mm for door hardware installations, while glass workers often need diamond drill bits of 6 mm to 50 mm. Large-diameter core bits of 150 mm to 200 mm are used in construction for HVAC ducts and utility penetrations.

Conclusion

Hollow drill bits come in an extensive range of specifications and sizes, with diameters starting from as small as 5 mm and extending beyond 200 mm for industrial applications. Their cutting depths vary from 25 mm to over 300 mm depending on the type, and their shank styles include SDS-plus, SDS-max, Weldon, and hex. They are manufactured from materials such as HSS, carbide, and diamond, each suitable for different materials ranging from softwood to reinforced concrete. Major brands such as Bosch, Hilti, Makita, DeWalt, Milwaukee, Starrett, and Fein each offer comprehensive product lines covering woodworking, metalworking, masonry, and tile applications. The specifications and sizes of hollow drill bits therefore represent a wide spectrum of solutions designed to meet the unique requirements of professional tradespeople and industrial users, ensuring precise, efficient, and durable hole-making across all sectors.