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Drill bits are the cutters of drill tools. Bits are interchangeable, meaning that they can be removed from the end of the drill, either to replace a worn part or to change the size of the part. A bit and brace, a hand-powered drill. ...
Modern hammer A tool is, among other things, a device that provides a mechanical or mental advantage in accomplishing a task. ...
This article describes the types of drill bits in terms of the design of the cutter. The other end of the drill bit, the shank, is described in the drill bit shank article. Drill bits come in standard sizes, described in the drill bit sizes article.
The term drill can refer to a drilling machine, or can refer to a drill bit for use in a drilling machine. In this article, for clarity, drill bit or bit is used throughout to refer to a bit for use in a drilling machine, and drill refers always to a drilling machine.
Some drill bits Scan, upload MH 17:24, 2004 Dec 4 (UTC) This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ...
Some drill bits Scan, upload MH 17:24, 2004 Dec 4 (UTC) This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ...
Twist Drill Bit
 Twist drill cutting edges The twist drill bit is the type produced in largest quantity today. It can be used to bore in metal, plastic, wood and stone.
The twist drill bit was invented in the US by Steven A. Morse in the 1860s. The original method of manufacture was to cut two grooves in opposite sides of a round bar, then to twist the bar to produce the helical flutes. This gave the tool its name. Nowadays, the drill is usually made by rotating the bar while moving it past a grinding wheel to cut the flutes. US,Us or us may stand for the United States of America us, the oblique case form of the English language pronoun we. ...
The word grinding can mean many things: Grinding is a manufacturing process that uses friction with a rough surface to wear away or smooth the surface of a work piece. ...
Tools recognisable as twist drill bits are currently produced in diameters covering the range at least from 0.05 mm to 100 mm. Lengths up to about 1000 mm are available for use in powered hand tools.
The geometry and sharpening of the cutting edges is crucial to the performance of the bit. Users often throw away small bits that become blunt, and replace with new, because the bits are inexpensive and sharpening well is difficult. For larger bits, special grinding jigs are available.
Manufacturers can produce specialist versions of the twist drill bit, varying the geometry and the materials used, to suit particular machinery and particular materials to be cut. Twist drill bits are available in the widest choice of tooling materials. However, it is still true that even for industrial users, most holes are still driled with a conventional bit of high speed steel.
Lip and Spur drill bit The lip and spur drill bit is a variation of the twist drill which is optimised for drilling in wood. It is also called the brad point bit or dowelling bit.
Conventional twist drill bits do tend to wander when presented to a flat workpiece. For metalwork, this is countered by drilling a pilot hole with a centre drill. In wood, there is another possible solution, that used in the lip and spur drill. The centre of the drill bit is given not the straight chisel of the twist drill, but a spur with a sharp point and four sharp corners to cut the wood. The sharp point of the spur simply pushes into the soft wood to keep the drill bit in line.
Metal has no long-distance structure, and an ordinary twist drill shears the edges of the hole cleanly. Wood drilled across the grain has long strands of wood fibre. These long strands tend to pull out of the wood hole, rather than being cleanly cut at the hole edge. The lip and spur drill bit has the outside corner of the cutting edges leading, so that it cuts the periphery of the hole before the inner parts of the cutting edges plane off the base of the hole. By cutting the periphery first, the lip maximises the chance that the fibres can be cut cleanly, rather than having them pull messily out of the timber.
Lip and spur drill bits are also effective in soft plastic. Conventional twist drills can, in some kinds of plastic, smear the edges of the hole, perhaps through local heating.
Lip and spur drill bits are ordinarily available in diameters from 3 to 16 mm.
Spade Drill Bit - This section currently under construction.
Forstner Drill Bit Forstner bits bore precise, flat-bottomed holes in wood, in any orientation with respect to the wood grain. They can cut on the edge of a block of wood, and can cut overlapping holes. Because of the flat bottom to the hole, they are useful for drilling through veneer already fixed, to add an inlay. They require great force to push them into the material, so are normally used in drill presses or lathes rather than in portable drills. They are impractical to use other than in power tools.
The bit has a centre point which locates the drill for the start of the cut (and incidentally spoils the flat bottom of the bored hole). The cylindrical cutter around the perimeter shears the wood fibres at the edge of the bore, and also guides the bit into the wood precisely. The tool in the image has a total of two cutting edges in this cylinder. Sawtooth Forstner bits are available, with many more cutting edges in the cylinder. These cut faster but produce a less clean hole.
Forstner bits have radial cutting edges to plane off the material at the bottom of the bored hole. The bit in the image has two radial edges. Other designs may have more.
Forstner bits have no mechanism to eject chips from the bore, and must be pulled out periodically to clear them.
Bits are commonly available in sizes from 8 mm to 50 mm diameter. Sawtooth bits are available up to 100 mm diameter.
Center Drill Bits
 Center drills, Numbers 1 through to 6 Center drill bits are used in metalworking to provide a starting hole for a larger sized drill bit, or a conical indentation in the end of a workpiece to mount a lathe centre. These centers are used when turning or grinding workpieces. A workpiece machined between centers can be safely removed from one process (perhaps turning in a lathe) and set up in a later process (perhaps a grinding operation) without losing any concentricity. Download high resolution version (1380x1416, 376 KB) Wikipedia does not have an article with this exact name. ...
Download high resolution version (1380x1416, 376 KB) Wikipedia does not have an article with this exact name. ...
Metalworking is the craft and practice of working with metals to create parts or structures. ...
This article is about a lathe as a tool. ...
The word grinding can mean many things: Grinding is a manufacturing process that uses friction with a rough surface to wear away or smooth the surface of a work piece. ...
Traditional twist drill bits may tend to wander when started on an unprepared surface. Once a bit wanders off-course it is difficult to bring it back on center. A center drill bit provides a good starting point as it is short and therefore has a reduced tendency to wander when drilling is started.
The small starting tip has a tendency to break, and it is economical and practical to make the drill bit double ended.
Core Drill Bit A core drill bit is used to enlarge an existing hole. The existing hole may be the result of a core from a casting or a stamped (punched) hole. The name of this bit is somewhat confusing. A diamond core drill bit cuts out a cylindrical core, cutting an annulus in the workpiece. A core drill bit is named because its first use was in drilling out the hole left by a core, a cyclinder placed in a mould for a casting. The core drill bit is solid, unlike the diamond core bit which is cylindrical. Download high resolution version (1842x444, 129 KB) Wikipedia does not have an article with this exact name. ...
Download high resolution version (1842x444, 129 KB) Wikipedia does not have an article with this exact name. ...
Sand casting is a means of producing rough metal castings that are further refined by any or all of hammer peening, shot peening, polishing, forging, plating, rough grinding, machine grinding or machining. ...
Core drill bits are similar in appearance to reamers as they have no cutting point or means of starting a hole. They have 3 or 4 flutes which enhances the finish of the hole and ensures the bit cuts evenly. Core drill bits differ from reamers in the amount of material they are intended to remove. A reamer can only enlarge a hole a slight amount, perhaps a millimeter. A core drill bit might be used to double the size of a hole. Using an ordinary two-flute twist drill to enlarge a hole tends to produce a less clean result, possibly out of round.
A reamer is a tool for enlarging holes and is used in metalworking. ...
Masonry Drill Bit  25 mm * 400 mm SDS-plus masonry bit The masonry bit shown here is a variation of the twist drill bit. The bulk of the tool is a relatively soft steel, and is machined with a mill rather than ground. An insert of tungsten carbide is brazed into the steel to provide the cutting edges. A Milling machine is a power-driven machine used for the complex shaping of metal (or possibly other materials) parts. ...
Tungsten carbide, WC or W2C, is a chemical compound containing tungsten and carbon similar to titanium carbide. ...
Brazing, not to be confused with Braising, is a joining process whereby a non-ferrous filler metal and an alloy are heated to melting temperature (above 450°C / 800 °F) and distributed between two or more close-fitting parts by capillary action. ...
Masonry bits typically are used with a hammer drill. The bit is both rotated and hammered into the workpiece. The hammering breaks up the masonry at the drill bit tip. The flutes of the drill bit body carry away the dust. Rotating the bit brings the cutting edges onto a fresh portion of the hole bottom with every hammer blow.
Masonry bits of the style shown are commonly available in diameters from 5 mm to 40 mm. For larger diameters, core bits are used. Masonry bits up to 1000 mm long can be used with hand-portable power tools, and are very effective for installing wiring and plumbing in existing buildings.
Diamond Core Drill Bit  115mm diamond core drill bit Diamond core drill bits are used to bore large holes in brick, concrete and stone. They are not generally used in other materials. The bit consists of a metal cylinder, usually relatively soft steel mounted on an arbor. Industrial diamonds are embedded at the open end of the cylinger. In the image, the diamonds are on the metal segments attached to the end. The segments are thicker than the cylinder wall, so most of the bit does not rub in the hole being bored. The sloping slots in the cylinder wall help carry the dust out. Diamond core drills can be used with or without water lubrication. The drill shown can cut a 115 mm diameter hole through a single-thickness brick wall in less than a minute, running at about 300 RPM. The resultant hole is very cleanly cut. A weathered brick wall. ...
This article is about the construction material. ...
Stone can refer to any of the following: Stone may be used as a building material, as in this dry stone wall and a wall made of stone tht has dog piss up it lol ha ha A rock. ...
Steel framework Steel is a metal alloy whose major component is iron, with carbon being the primary alloying material. ...
In Valencia a newly-installed pergola shows its structure, which the climbing roses will cover. ...
A scattering of round-brilliant cut diamonds shows off the many reflecting facets. ...
A lubricant (colloquially, lube) is a substance introduced between two moving surfaces to reduce the friction and wear between them. ...
This form of core drill wanders hopelessly when presented to a flat surface, and needs a centring mechanism. The arbor can carry a drill bit to bore a centring hole, but the version shown has a plain 10 mm rod. A 10 mm masonry twist drill must first be used to drill the centring hole for the rod. A wooden or stone template, a close fit for the cylinder, can also be used to guide the bit at the start of the cut. After the first few millimeters of cut, the centring mechanism may no longer be needed, although it will help the bit to bore without wandering in a deep hole.
Diamond core drill bits for use with portable drills are commonly available in diameters from 20 mm to 130 mm. The only limit on length of the cylinder, and thus depth of the hole, is the need to remove the bit from the hole to clear dust. 300 mm cylinder length is not uncommon, although shorter bits are usual.
Holesaw  Holesaw dismounted from arbor Holesaws have the same general mechanical construction as the diamond core drill bit, but, instead of the abrasive effect of diamonds, the holesaw uses the cutting effect of saw teeth. The open end of the saw's cylinder is milled with saw teeth. Instead of masonry, the holesaw is suitable for cutting wood, plastic, soft plaster or soft metal.
The set of the saw teeth makes the cut annulus slightly wider than the cylinder wall thickness, so the cylinder doesn't rub in the cut. Just as in the diamond core drill bit, the cylinder is mounted on an arbor with a centre pilot drill, and has sloping slots to clear sawdust.
The saw pictured was made by Sandvik of Sweden in about 1988. It cuts a 52mm diameter hole.
Brace Drill Bit  3/4 inch brace drill bit tip detail The brace drill bit is optimised for drilling in wood with a hand brace. Many different designs have been produced.
The centre of the bit is a tapered screw thread. This screws into the wood as the drill is turned, and pulls the bit into the wood. There is no need for any force to push the bit into the workpiece, only the torque to turn the bit. This is ideal for a bit for a hand tool. To pull the bit from the hole, either the female thread in the wood workpiece must be stripped, or the rotation of the bit must be reversed.
The edge of the bit has a sharpened spur to cut the fibres of the wood, as in the lip and spur drill. A radial cutting edge planes the wood from the base of the hole. In this version, there is no helix to remove chips from the hole. The drill must be preiodically withdrawn to clear the chips.
Some versions have two spurs. Some have two radial cutting edges.
Brace drill bits are made of relatively soft steel, and can be sharpened with a file.
The drill bit shown was made sometime before 1950, and still works to drill holes in 2005. It drills a hole of diameter 3/4 inch.
Auger Bit The cutting principles of the auger bit are the same as those of the brace drill bit above. The auger adds a long deep helix for effective chip removal.
The bit shown in the picture is a modern design for use in portable power tools, made in the UK in about 1995. It has a single spur, a single radial cutting edge and a single-start thread for its helix. Similar auger bits are made with diameters from 6 mm to 30 mm. Augers up to 600 mm long are available, where the chip-clearing capability is especially valuable for drilling deep holes.
Gimlet Bit The gimlet bit is a very old design. The bit is the same style as that used in the gimlet, a self-contained tool for boring small holes in wood by hand. Since about 1850, gimlets have had a variety of cutter designs, but some are still produced with the original version. The gimlet bit is intended to be used in a hand brace for drilling into wood. It is the usual style of bit for use in a brace for holes below about 7 mm diameter. A gimlet A gimlet, according to its original meaning, is a kind of tool for boring holes. ...
The tip of the gimlet bit acts as a tapered screw, to draw the bit into the wood and to begin forcing aside the wood fibres, without necessarily cutting them. The cutting action occurs at the side of the broadest part of the cutter. Most drills cut the base of the hole. The gimlet bit cuts the side of the hole.
The gimlet bit in the photos at right was made sometime before 1950.
Spoon Bit - This section currently under construction.
Half Round Bit - This section currently under construction.
Glass Bit - This section currently under construction.
Adjustable Holesaw - This section currently under construction.
Expansive Bit - This section currently under construction.
Tungsten Carbide Core Bit - This section currently under construction.
Installer Bit - This section currently under construction.
30 mm Hinge sinker Bit The hinge sinker bit is an example of a custom drill design for a specific application. Many European kitchen cabinets are made from chipboard with a laminated plastic veneer. The chipboard is not very strong, and the screws of butt hinges tend to pull out. A specialist hinge has been developed which uses the walls of a 30 mm diameter hole, bored in the chipboard, for support. This is a very common and relatively successful construction method. The term plastics covers a range of synthetic or semi-synthetic polymerization products. ...
A hinge is a mechanical device that connects two solid objects, allowing a relative motion between them. ...
A forstner bit could bore the mounting hole for the hinge, but chipboard is a very abrasive material. Softer steel cutting edges soon wear. A tungsten carbide cutter is needed, and making that in the form of a forstner bit is impractical. So, this special drill is commonly used. It has cutting edges of tungsten carbide brazed to a steel body. A centre spur keeps the bit from wandering.
Tungsten carbide, WC or W2C, is a chemical compound containing tungsten and carbon similar to titanium carbide. ...
Oil drilling bits
 Tricone bit for well drilling. There are two types of drill bits used in oil or natural gas drilling rigs, a drag bit, and a rock bit: Wikipedia does not have an article with this exact name. ...
Wikipedia does not have an article with this exact name. ...
An oil well is a laymans term for any perforation through the Earths surface designed to find and release both petroleum oil and gas hydrocarbons. ...
Natural gas rig Natural gas (commonly refered to as gas in many countries) is a gaseous fossil fuel consisting primarily of methane. ...
Natural gas drilling rig A drilling rig or oil rig is a structure housing equipment used to drill for and extract oil or natural gas from underground reservoirs. ...
- a drag bit is used for soft rocks, like sand and clay. The drill stem is rotated, and teeth on the bit tear up the rock.
- a rock bit (also called a roller bit) consists of teeth on wheels which turn as the drill stem is rotated. These teeth apply a shearing pressure to the rock, breaking it up into small pieces.
The original patent for the rotary rock bit was issued to Howard Hughes Sr. in 1909. It consisted of two interlocking wheels. The success of this bit lead to the founding of the Sharp-Hughes Tool Company. In physics and mechanics, shear refers to a deformation that causes parallel surfaces to slide past one another (as opposed to compression and tension, which cause parallel surfaces to move towards or away from one another). ...
A patent is a set of exclusive rights granted by a state to a person for a fixed period of time in exchange for the regulated, public disclosure of certain details of a device, method, process or substance (known as an invention) which is new, inventive and useful. ...
Howard R. Hughes, Sr. ...
1909 was a common year starting on Friday (see link for calendar). ...
Hughes Tool Company was established in 1909 when Howard R. Hughes, Sr. ...
In 1933 two Hughes engineers invented the tricone bit. This bit has three wheels and is still the dominant bit in the market today. The Hughes patent for the tricone bit lasted until 1951, after which time other companies started making similar bits. However, the Hughes’s market share is still 40% of the worlds drill bit market. 1933 was a common year starting on Sunday (link will take you to calendar). ...
1951 was a common year starting on Monday; see its calendar. ...
Materials for Bit Construction - This section under construction
Bit Coatings - This section under Construction
See Also A bit and brace, a hand-powered drill. ...
References Oberg, Erik 1881-1951 (1992). Machinery's handbook. Industrial Press Inc.. ISBN 0-8311-2492-X. | 
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