character of cutting tool
For the types used in boring holes in the ground, see well drilling Drill ( upper leave ), mounted on a pistol-grip electric drill A set of masonry drills

Drills are cutting tools used to remove corporeal to create holes, about always of round cross-section. Drills come in many sizes and shapes and can create unlike kinds of holes in many different materials. In orderliness to create holes drill bits are normally attached to a drill, which powers them to cut through the workpiece, typically by rotation. The drill will grasp the upper end of a bit called the shank in the chuck. Drills come in standardize drill sting sizes. A comprehensive drill bit and tap size chart lists measured and imperial size drills alongside the ask screw tap sizes. There are besides certain specialized drill bits that can create holes with a non-circular cross-section. [ 1 ]


Drill geometry has respective characteristics :

  • The spiral (or rate of twist) in the drill bit controls the rate of chip removal. A fast spiral (high twist rate or “compact flute”) drill bit is used in high feed rate applications under low spindle speeds, where removal of a large volume of chips is required. Low spiral (low twist rate or “elongated flute”) drill bits are used in cutting applications where high cutting speeds are traditionally used, and where the material has a tendency to gall on the bit or otherwise clog the hole, such as aluminum or copper.
  • The point angle, or the angle formed at the tip of the bit, is determined by the material the bit will be operating in. Harder materials require a larger point angle, and softer materials require a sharper angle. The correct point angle for the hardness of the material influences wandering, chatter, hole shape, and wear rate.
  • The lip angle determines the amount of support provided to the cutting edge. A greater lip angle will cause the bit to cut more aggressively under the same amount of point pressure as a bit with a smaller lip angle. Both conditions can cause binding, wear, and eventual catastrophic failure of the tool. The proper amount of lip clearance is determined by the point angle. A very acute point angle has more web surface area presented to the work at any one time, requiring an aggressive lip angle, where a flat bit is extremely sensitive to small changes in lip angle due to the small surface area supporting the cutting edges.
  • The functional length of a bit determines how deep a hole can be drilled, and also determines the stiffness of the bit and accuracy of the resultant hole. While longer bits can drill deeper holes, they are more flexible meaning that the holes they drill may have an inaccurate location or wander from the intended axis. Twist drill bits are available in standard lengths, referred to as Stub-length or Screw-Machine-length (short), the extremely common Jobber-length (medium), and Taper-length or Long-Series (long).

Most drill bits for consumer use have straight shanks. For heavy duty drilling in diligence, bits with sharpen shanks are sometimes used. other types of shank used include hex-shaped, and diverse proprietary agile release systems. The diameter-to-length proportion of the drill spot is normally between 1:1 and 1:10. much higher ratios are possible ( for example, “ aircraft-length ” bend bits, pressured-oil gun bore bits, etc. ), but the higher the proportion, the greater the technical challenge of producing good work. The best geometry to use depends upon the properties of the fabric being drilled. The following mesa lists geometries recommended for some normally drilled materials .

Tool geometry[2]
Workpiece material Point angle Helix angle Lip relief angle
Aluminum 90 to 135 32 to 48 12 to 26
Brass 90 to 118 0 to 20 12 to 26
Cast iron 90 to 118 24 to 32 7 to 20
Mild steel 118 to 135 24 to 32 7 to 24
Stainless steel 118 to 135 24 to 32 7 to 24
Plastics 60 to 90 0 to 20 12 to 26


many different materials are used for or on drill bits, depending on the want application. many hard materials, such as carbides, are much more brittle than steel, and are far more capable to breaking, particularly if the drill is not held at a very ceaseless lean to the workpiece ; e.g., when hand-held .


  • Soft low-carbon steel bits are inexpensive, but do not hold an edge well and require frequent sharpening. They are used only for drilling wood; even working with hardwoods rather than softwoods can noticeably shorten their lifespan.
  • Bits made from high-carbon steel are more durable than low-carbon steel bits due to the properties conferred by hardening and tempering the material. If they are overheated (e.g., by frictional heating while drilling) they lose their temper, resulting in a soft cutting edge. These bits can be used on wood or metal.
  • High-speed steel (HSS) is a form of tool steel; HSS bits are hard and much more resistant to heat than high-carbon steel. They can be used to drill metal, hardwood, and most other materials at greater cutting speeds than carbon-steel bits, and have largely replaced carbon steels.
  • Cobalt steel alloys are variations on high-speed steel that contain more cobalt. They hold their hardness at much higher temperatures and are used to drill stainless steel and other hard materials. The main disadvantage of cobalt steels is that they are more brittle than standard HSS.


  • Tungsten carbide and other carbides are extremely hard and can drill virtually all materials, while holding an edge longer than other bits. The material is expensive and much more brittle than steels; consequently they are mainly used for drill-bit tips, small pieces of hard material fixed or brazed onto the tip of a bit made of less hard metal. However, it is becoming common in job shops to use solid carbide bits. In very small sizes it is difficult to fit carbide tips; in some industries, most notably printed circuit board manufacturing, requiring many holes with diameters less than 1 mm, solid carbide bits are used.
  • Polycrystalline diamond (PCD) is among the hardest of all tool materials and is therefore extremely resistant to wear. It consists of a layer of diamond particles, typically about 0.5 mm (0.020 in) thick, bonded as a sintered mass to a tungsten-carbide support. Bits are fabricated using this material by either brazing small segments to the tip of the tool to form the cutting edges or by sintering PCD into a vein in the tungsten-carbide “nib”. The nib can later be brazed to a carbide shaft; it can then be ground to complex geometries that would otherwise cause braze failure in the smaller “segments”. PCD bits are typically used in the automotive, aerospace, and other industries to drill abrasive aluminum alloys, carbon-fiber reinforced plastics, and other abrasive materials, and in applications where machine downtime to replace or sharpen worn bits is exceptionally costly. PCD is not used on ferrous metals due to excess wear resulting from a reaction between the carbon in the PCD and the iron in the metal.


Diamond-coated 2 millimeter bits, used for drilling materials such as methamphetamine

  • Black oxide is an inexpensive black coating. A black oxide coating provides heat resistance and lubricity, as well as corrosion resistance. The coating increases the life of high-speed steel bits.
  • Titanium nitride (TiN) is a very hard metallic material that can be used to coat a high-speed steel bit (usually a twist bit), extending the cutting life by three or more times. Even after sharpening, the leading edge of coating still provides improved cutting and lifetime.
  • Titanium aluminum nitride (TiAlN) is a similar coating that can extend tool life five or more times.
  • Titanium carbon nitride (TiCN) is another coating also superior to TiN.
  • Diamond powder is used as an abrasive, most often for cutting tile, stone, and other very hard materials. Large amounts of heat are generated by friction, and diamond-coated bits often have to be water-cooled to prevent damage to the bit or the workpiece.
  • Zirconium nitride has been used as a drill-bit coating for some tools under the Craftsman brand name.
  • Al-Chrome Silicon Nitride (AlCrSi/Ti)N is a multilayer coating made of alternating nanolayer, developed using chemical vapor deposition technique, is used in drilling carbon fiber reinforced polymer (CFRP) and CFRP-Ti stack. (AlCrSi/Ti)N is a superhard ceramic coating, which performs better than other coated and uncoated drill.[3][4]
  • BAM coating is Boron-Aluminum-Magnesium BAlMgB14 is a superhard ceramic coating also used in composite drilling.[3][5]

Universal bits.

General-purpose bore bits can be used in forest, alloy, credit card, and most other materials .

twist bore bite.

The bend exercise morsel is the type produced in largest quantity today. It comprises a cut point at the tip off of a cylindrical shaft with coiling flutes ; the flutes act as an Archimedean fuck and lift swarf out of the hole. The modern-style writhe drill morsel was invented by Sir Joseph Whitworth in 1860. They were belated improved by Steven A. Morse of East Bridgewater, Massachusetts, who experimented with the pitch of the device. [ 6 ] [ 7 ] [ 8 ] The original method acting of industry was to cut two grooves in opposite sides of a round bar, then to twist the bar ( giving the tool its appoint ) to produce the coiling flutes. Nowadays, the drill morsel is normally made by rotating the bar while moving it past a grind roulette wheel to cut the flutes in the same manner as cutting coiling gears. twist drill bits range in diameter from 0.002 to 3.5 in ( 0.051 to 88.900 millimeter ) [ 9 ] and can be angstrom long as 25.5 in ( 650 millimeter ). [ 10 ] The geometry and sharpen of the cut edges is crucial to the performance of the bite. Small bits that become deaden are much discarded because sharpening them correctly is unmanageable and they are brassy to replace. For larger bits, special grind jigs are available. A particular joyride mill is available for sharpening or reshaping cutting surfaces on turn bore bits in order to optimize the bit for a particular material. Manufacturers can produce special versions of the writhe drill bit, varying the geometry and the materials used, to suit particular machinery and especial materials to be cut. Twist drill bits are available in the widest choice of tooling materials. however, even for industrial users, most holes are drilled with criterion high-speed steel bits .
A 5 millimeter carbide bit displaying shallow point angle. The most common writhe bore spot ( sold in general hardware stores ) has a point fish of 118 degrees, satisfactory for use in wood, metallic element, formative, and most other materials, although it does not perform vitamin a well as using the optimum fish for each material. In most materials it does not tend to wander or dig in. A more aggressive lean, such as 90 degrees, is suited for very soft plastics and other materials ; it would wear quickly in hard materials. Such a bite is generally self-starting and can cut very quickly. A shallower lean, such as 150 degrees, is suited for drill steels and early tougher materials. This style of bite requires a crank hole, but does not bind or suffer previous wear then long as a suitable fertilize rate is used. Drill bits with no point angle are used in situations where a blind, flat-bottomed hole is required. These bits are very sensitive to changes in lip angle, and evening a little change can result in an inappropriately firm cutting drill bit that will suffer previous clothing. Long series drill bits are unusually long device drill bits. however, they are not the best creature for routinely drilling deep holes, as they require patronize withdrawal to clear the flutes of swarf and to prevent breakage of the bit. rather, gun drill ( through coolant drill ) bits are preferred for deep fix drilling .

step drill bit.

A step drill bit is a drill bit that has the tip ground down to a different diameter. The passage between this ground diameter and the original diameter is either straight, to form a counterbore, or angled, to form a set. The advantage to this stylus is that both diameters have the lapp flute characteristics, which keeps the snatch from clogging when drill in softer materials, such as aluminum ; in contrast, a drill morsel with a slip-on collar does not have the lapp benefit. Most of these bits are custom-made for each application, which makes them more expensive. [ 11 ]


A match of unibits. A unibit ( much called a step drill bit ) is a roughly conic spot with a stairstep profile. [ 11 ] ascribable to its design, a single bit can be used for drilling a wide range of hole sizes. Some bits come to a point and are therefore self-starting. The larger-size bits have blunt tips and are used for hole enlarge. Unibits are normally used on sheet metallic [ 11 ] and in general construction. One exercise bite can drill the entire range of holes necessity on a countertop, speeding up installation of fixtures. They are frequently used on softer materials, such as plywood, atom display panel, wallboard, acrylic, and laminate. They can be used on very thin plane metallic, but metals tend to cause previous bit wear and dull. Unibits are ideal for use in electric work where reduce steel, aluminum or credit card boxes and chassis are encountered. The short length of the unibit and ability to vary the diameter of the finished hole is an advantage in chassis or front panel exercise. The eat up trap can often be made quite fluent and burr-free, specially in fictile. An extra use of unibits is deburring holes left by other bits, as the acute increase to the future dance step size allows the cutting edge to scrape burrs off the introduction surface of the workpiece. however, the directly flute is poor people at chip expulsion, and can cause a bur to be formed on the die side of the hole, more so than a spiral wind drill bit turning at high speed. The unibit was invented by Harry C. Oakes and patented in 1973. [ 12 ] It was sold entirely by the Unibit Corporation in the 1980s until the patent expired, and was later sold by other companies. Unibit is a hallmark of Irwin Industrial Tools. Although it is claimed that the step drill was invented by Harry C. Oakes it was in fact first base produced by Bradley Engineering, Wandsworth, London in the 1960s and named the Bradrad. It was marketed under this name until the patent was sold to Halls by whom it is still produced .

Hole saw.

1.25 in ( 32 millimeter ) hole saw act. Hole saws take the form of a short open cylinder with saw-teeth on the open edge, used for making relatively boastfully holes in sparse material. They remove material merely from the edge of the trap, cutting out an intact phonograph record of material, unlike many drills which remove all substantial in the home of the hole. They can be used to make large holes in wood, sheet metallic element and other materials .

Metal drill bits.

Center and spotting drill sting.

Center drill bits, numbers 1 to 6 Center drill bits, occasionally known as Slocombe drill bits, are used in metalworking to provide a start hole for a larger-sized drill snatch or to make a conic indentation in the end of a workpiece in which to mount a lathe center. In either use, the list seems appropriate, as the morsel is either establishing the center of a hole or making a conic hole for a lathe center. however, the true purpose of a center drill snatch is the latter undertaking, while the former undertaking is best done with a spotting drill bit ( as explained in contingent below ). however, because of the frequent lumping together of both the terminology and the tool use, suppliers may call focus on drill bits combined-drill-and-countersinks in arrange to make it uniquely clear what product is being ordered. They are numbered from 00 to 10 ( smallest to largest ) .

Use in making holes for lathe centers.

Center drill bits are meant to create a conic fix for “ between centers ” fabricate processes ( typically lathe or cylindrical-grinder work ). That is, they provide a placement for a ( live, dead, or drive ) center to locate the part about an axis. A workpiece machined between centers can be safely removed from one process ( possibly turning in a lathe ) and set up in a late process ( possibly a grind operation ) with a negligible loss in the co-axiality of features ( normally full indicator read ( TIR ) less than 0.002 in ( 0.05 millimeter ) ; and TIR < 0.0001 in ( 0.003 millimeter ) is held in cylindrical grind operations, arsenic long as conditions are discipline ) .

Use in spotting hole centers.

traditional wrench drill bits may tend to wander when started on an unprepared surface. once a act wanders off course it is unmanageable to bring it back on center. A concentrate drill bit frequently provides a fair starting point as it is inadequate and consequently has a reduced inclination to wander when drill is started. While the above is a park use of center drill bits, it is a technically incorrect commit and should not be considered for production function. The discipline instrument to start a traditionally drilled hole ( a hole drilled by a high-speed steel ( HSS ) wind exercise bit ) is a spotting drill bit ( or a spot drill bit, as they are referenced in the U.S. ). The include angle of the spot drill bite should be the same as, or greater than, the conventional drill morsel so that the drill bit will then start without undue stress on the bit ‘s corners, which would cause premature failure of the bit and a personnel casualty of hole quality. Most modern solid-carbide bits should not be used in conjunction with a spot drill bit or a center exercise bit, as solid-carbide bits are specifically designed to start their own hole. normally, spotlight drilling will cause previous failure of the solid-carbide bite and a sealed loss of hole quality. If it is deemed necessity to chamfer a hole with a spot or focus on drill bite when a solid-carbide bore morsel is used, it is best practice to do so after the hole is drilled. [ citation needed ] When drilling with a hand-held drill the flexibility of the bit is not the primary source of inaccuracy—it is the user ‘s hands. consequently, for such operations, a center punch is often used to spot the hole center anterior to drilling a fender hole .

core drill piece.

HSS kernel drills in versatile sizes A magnetic core drill machine making fix with annular cutter ( core drill ) The term core drill bit is used for two quite different tools .

Enlarging holes.

A morsel used to enlarge an existing hole is called a core drill bit. The existing hole may be the consequence of a effect from a casting or a stamp ( punched ) hole. The name comes from its inaugural use, for drilling out the hole left by a foundry core, a cylinder placed in a mildew for a vomit that leaves an irregular hole in the product. This core bore bit is solid. These core drill bits are exchangeable 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 fabric they are intended to remove. A reamer is lone intended to enlarge a hole a flimsy measure which, depending on the reamers size, may be anything from 0.1 millimeter to possibly a millimeter. A core exercise bit may be used to double the size of a hole. Using an ordinary two-flute bend drill bite to enlarge the hole resulting from a casting kernel will not produce a fairly result, the leave will possibly be out of round, off center and broadly of poor finish. The two fluted drill bit besides has a tendency to grab on any protuberance ( such as brassy ) which may occur in the product .

Extracting core.

A hollow cylindrical bite which will cut a hole with an annular cross-section and leave the inner cylinder of corporeal ( the “ core ” ) entire, frequently removing it, is besides called a core bore bite or annular tender. Unlike early drills, the function is much to retrieve the core quite than simply to make a hole. A diamond core drill bit is intended to cut an annular hole in the workpiece. bombastic bits of similar shape are used for geological shape, where a deep hole is drilled in sediment or ice and the drill bit, which immediately contains an integral core of the material drilled with a diameter of several centimeters, is retrieved to allow study of the class .

Countersink bite.

A countersink is a conic hole cut into a manufactured aim ; a countersink bit ( sometimes called just set ) is the cutter used to cut such a hole. A common manipulation is to allow the drumhead of a gobble or prison guard, with a shape precisely matching the set hole, to sit flush with or below the airfoil of the surrounding substantial. ( By comparison, a counterbore makes a flat-bottomed hole that might be used with a hex-headed capscrew. ) A countersink may besides be used to remove the bur left from a bore or exploit operation .

Ejector drill bit.

Used about entirely for deep hole drill of medium to large diameter holes ( approximately 3⁄4–4 in or 19–102 mm diameter ). An cartridge ejector exercise sting uses a particularly designed carbide cutter at the point. The bit body is basically a pipe within a metro. Flushing water travels down between the two tubes. Chip removal is bet on through the kernel of the spot .

Gun drill bit.

Gun drills are straight fluted drills which allow cutting fluid ( either compressed publicize or a desirable liquid ) to be injected through the drill ‘s hole body to the cutting face .

Indexable drill sting.

Indexable drill bits are chiefly used in CNC and other high preciseness or production equipment, and are the most expensive character of drill bit, costing the most per diameter and length. Like indexable lathe tools and milling cutters, they use replaceable carbide or ceramic inserts as a cutting face to alleviate the indigence for a tool molar. One insert is responsible for the out radius of the cut, and another cut-in is responsible for the inner spoke. The tool itself handles the point disfigurement, as it is a low-wear job. The snatch is hardened and coated against wear far more than the average bore bit, as the shank is non-consumable. Almost all indexable drill bits have multiple coolant channels for drawn-out creature animation under big use. They are besides readily available in curious configurations, such as straight flute, fast spiral, multiflute, and a variety show of cutting confront geometries. typically indexable drill bits are used in holes that are no deeper than about 5 times the sting diameter. They are capable of quite high axile loads and cut very fast .

Left-hand bit.

An 1/8 column inch left-hand drill bit Left-hand bits are about constantly flex bits and are predominantly used in the repetition engineering industry on screw machines or drilling heads. levorotary drill bits allow a machine operation to continue where either the spindle can not be reversed or the purpose of the machine makes it more effective to run morganatic. With the increased manipulation of the more versatile CNC machines, their habit is less common than when specialize machines were required for machining tasks. Screw extractors are basically left bits of specify shape, used to remove common right screws whose heads are broken or besides damaged to allow a screwdriver topple to engage, making use of a screwdriver impossible. The extractor is pressed against the damaged head and rotated counter-clockwise and will tend to jam in the damaged head and then turn the screw counter-clockwise, unscrewing it. For screws that break off deep in the hole, an cartridge extractor hardened will frequently include left handed drill bits of the allow diameters so that grab holes can be drilled into the screws in a bequeath handed commission, preventing foster reduce of the interrupt assemble .

Metal spade bit.

A nigger drill spot for metallic element is a two part bit with a joyride holder and an insertable peak, called an slip in. The inserts come in versatile sizes that range from 7⁄16 to 2.5 inches ( 11 to 64 millimeter ). The joyride holder normally has a coolant passage running through it. [ 13 ] They are capable of cutting to a depth of about 10 times the bit diameter. This type of exercise snatch can besides be used to make step holes .

straight fluted bit.

Straight fluted drill bits do not have a coiling wind like twist bore bits do. They are used when drilling bull or boldness because they have less of a tendency to “ dig in ” or grab the corporeal .


A trepan, sometimes called a BTA bore bite ( after the Boring and Trepanning Association ), is a drill snatch that cuts an annulus and leaves a center core. Trepans normally have multiple carbide inserts and rely on water to cool the cutting tips and to flush chips out of the hole. Trepans are frequently used to cut large diameters and cryptic holes. typical bit diameters are 6–14 in ( 150–360 millimeter ) and hole depth from 12 in ( 300 millimeter ) up to 71 feet ( 22 thousand ) .

Wood drill bits.

Brad charge sting.

A 10.5 millimeter brad point drill moment The brad point drill bit ( besides known as lip and spur drill bit, and dowel drill bit ) is a variation of the wind exercise spot which is optimized for drill in wood. conventional twist exercise bits tend to wander when presented to a flat workpiece. For metalworking, this is countered by drilling a pilot program hole with a spot drill bit. In wood, the brad detail bore spot is another solution : the center of the drill bit is given not the straight chisel of the wind drill bit, but a spur with a sharp point, and four sharp corners to cut the forest. While drill, the acuate degree of the spur pushes into the soft wood to keep the exercise moment in line. Metals are typically isotropic, so even an ordinary twist drill morsel will shear the edges of the hole flawlessly. Wood drilled across the grain, however, produces long strands of forest fiber. These retentive strands tend to pull out of the hole, quite than being cleanly cut at the hole boundary. The brad point drill bite has the outside corner of the dilute edges leadership, so that it cuts the periphery of the hole before the inside parts of the cut edges plane off the root of the hole. By cutting the periphery first, the lip maximizes the chance that the fibers can be cut flawlessly, rather than having to be pulled messily from the timber. Brad period drill bits are besides effective in soft plastic. When using conventional device drill bits in a hand-held bore, where the drilling commission is not maintained perfectly throughout the operation, there is a tendency for fix edges to be “ smeared ” due to side friction and heat. In metal, the brad point drill spot is confined to drilling alone the thinnest and softest plane metals, ideally with a bore press. The bits have an extremely fast cutting joyride geometry : no steer slant, combined with a large ( considering the apartment switch off edge ) sass angle, causes the edges to take a very aggressive reduce with relatively little orient imperativeness. This means these bits tend to bind in metal ; given a workpiece of sufficient fineness, they have a leaning to punch through and leave the morsel ‘s cross-sectional geometry behind. Brad indicate exercise bits are normally available in diameters from 3–16 millimeter ( 0.12–0.63 in ).

Wood spade moment.

spade bits are used for grating bore in wood. They tend to cause splintering when they emerge from the workpiece. Woodworkers avoid splintering by finishing the hole from the face-to-face side of the work. Spade bits are flat, with a center point and two cutters. The cutters are frequently equipped with spurs in an attack to ensure a cleaner fix. With their little shank diameters relative to their boring diameters, spade act shanks often have flats forged or ground into them to prevent slipping in drill chucks. Some bits are equipped with long shanks and have a small hole drilled through the flat part, allowing them to be used much like a bell-hanger act. Intended for gamey amphetamine function, they are used with electric hand drills. Spade bits are besides sometimes referred to as “ paddle bits ”. Spade exercise bits are normally available in diameters from 6 to 36 millimeter, or 1⁄4 to 1+1⁄2 inches .

Spoon bit.

Spoon bits consist of a groove shank with a compass point shaped reasonably like the bowl of a spoon, with the cutting edge on the conclusion. The more common character is like a dent moment that ends in a little point. This is helpful for starting the hole, as it has a center that will not wander or walk. These bits are used by chair-makers for bore or reaming holes in the seats and arms of chairs. Their design is ancient, going rear to Roman times. Spoon bits have even been found in Viking excavations. Modern spoon bits are made of hand-forged carbon steel, cautiously heat-treated and then pass ground to a fine edge. spoon bits are the traditional drilling tools used with a brace. They should never be used with a power drill of any kind. Their key advantage over regular brace bits and power drill bits is that the slant of the trap can be adjusted. This is very important in chairmaking, because all the angles are normally eyeballed. Another advantage is that they do not have a jumper cable prison guard, so they can be drilled successfully in a chair leg without having the head screw peek out the early side. When reaming a pre-bored straight-sided hole, the spoon act is inserted into the hole and rotated in a clockwise direction with a carpenters ‘ brace until the desire sharpen is achieved. When boring into solid wood, the piece should be started in the vertical position ; after a “ dish ” has been created and the spot has begun to “ bite ” into the wood, the angle of bore can be changed by tilting the brace a act out of the vertical. Holes can be drilled precisely, cleanly and quickly in any wood, at any angle of incidence, with entire manipulate of guidance and the ability to change that direction at will. Parallel spoon bits are used primarily for boring holes in the seat of a Windsor president to take the back spindles, or similar round-tenon work when assembling furniture frames in green woodworking work. The spoon morsel may be honed by using a slipstone on the at heart of the cut edge ; the outside edge should never be touched .

Forstner bit.

25 millimeter ( 1.0 in ) Forstner moment Another Forstner morsel Forstner bits, named after their inventor, [ when? ] Benjamin Forstner, give birth precise, flat-bottomed holes in wood, in any orientation with regard to the wood grain. They can cut on the border of a freeze of wood, and can cut overlap holes ; for such applications they are normally used in drill presses or lathes rather than in hand-held electric drills. Because of the flat bottom of the hole, they are useful for drilling through veneer already glued to add an inlay. The bite includes a center brad point which guides it throughout the edit ( and incidentally spoils the differently flat penetrate of the hole ). The cylindrical stonecutter around the circumference shears the forest fibers at the edge of the bear, and besides helps guide the spot into the material more precisely. Forstner bits have radial edit edges to plane off the material at the bottom of the trap. The bits shown in the images have two radial edges ; early designs may have more. Forstner bits have no mechanism to clear chips from the hole, and therefore must be pulled out sporadically. Sawtooth bits are besides available, which include many more cut edges to the cylinder. These cut fast, but produce a more ragged hole. They have advantages over Forstner bits when boring into end granulate. Bits are normally available in sizes from 8–50 millimeter ( 0.3–2.0 in ) diameter. Sawtooth bits are available up to 100 millimeter ( 4 in ) diameter. in the first place the Forstner bit was very successful with gunsmiths because of its ability to drill an extremely smooth-sided hole. [ citation needed ]

Center sting.

The center act is optimized for drill in wood with a pass brace. many different designs have been produced. The center of the bite is a tapered sleep together thread. This screws into the wood as the spot is turned, and pulls the spot into the wood. There is no necessitate for any power to push the act into the workpiece, only the torsion to turn the spot. This is ideal for a bit for a bridge player tool. The radial cut edges remove a slice of wood of thickness peer to the pitch of the central screw for each rotation of the snatch. To pull the snatch from the trap, either the female thread in the wood workpiece must be stripped, or the rotation of the bit must be reversed. The edge of the morsel has a sharpened spur to cut the fibers of the wood, as in the brad point bore bit. A radial clipping edge planes the wood from the base of the hole. In this interpretation, there is minimal or no spiral to remove chips from the hole. The bit must be sporadically withdrawn to clear the chips. Some versions have two spurs. Some have two radial cutting edges. Center bits do not cut well in the end grain of wood. The cardinal screw tends to pull out, or to split the forest along the texture, and the radial edges have trouble oneself cutting through the hanker wood fibers. Center bits are made of relatively soft steel, and can be sharpened with a file .

Auger bite.

The cutting principles of the plumber’s snake spot are the lapp as those of the center field spot above. The auger adds a farseeing abstruse spiral flute for effective chip removal. Two styles of auger act are normally used in hand braces : the Jennings or Jennings-pattern bite has a self-feeding sleep together tip, two spurs and two radial cutting edges. This bit has a double flute starting from the geld edges, and extending several inches up the shank of the moment, for barren removal. This convention of morsel was developed by Russell Jennings in the mid-19th century. The Irwin or solid-center plumber’s snake bit is alike, the only dispute being that one of the cut edges has only a “ vestigal flute ” supporting it, which extends alone about 1⁄2 in ( 13 millimeter ) up the shank before ending. The other flute continues full-length up the shank for godforsaken removal. The Irwin bit may afford greater space for waste removal, greater intensity ( because the design allows for a center shank of increase size within the flutes, as compared to the Jenning bits ), or smaller manufacture costs. This expressive style of bit was invented in 1884, and the rights sold to Charles Irwin who patented and marketed this pattern the stick to year. Both styles of auger bits were manufactured by respective companies throughout the early- and mid-20th century, and are still available new from choose sources today. The diameter of plumber’s snake bits for hand braces is normally expressed by a individual number, indicating the size in 16ths of an edge. For case, # 4 is 4/16 or 1/4 in ( 6 millimeter ), # 6 is 6/16 or 3/8 in ( 9 millimeter ), # 9 is 9/16 in ( 14 millimeter ), and # 16 is 16/16 or 1 in ( 25 millimeter ). Sets normally consist of # 4-16 or # 4-10 bits. The bit shown in the picture is a modern purpose for use in portable might tools, made in the UK in about 1995. It has a single spur, a individual radial cut edge and a single flute. like auger bits are made with diameters from 6 millimeter ( 3/16 in ) to 30 millimeter ( 1 3/16 in ). Augers up to 600 millimeter ( 2.0 foot ) long are available, where the chip-clearing capability is specially valuable for drilling bass holes .

Gimlet moment.

The auger bit is a very old design. The piece is the lapp style as that used in the gimlet, a self-contained cock for boring little holes in wood by pass. Since about 1850, gimlets have had a diverseness of tender designs, but some are hush produced with the original interpretation. The auger sting is intended to be used in a hand brace for drilling into wood. It is the common style of sting for practice in a brace for holes below approximately 7 mm ( 0.28 in ) diameter. The lean of the auger spot acts as a taper screw, to draw the piece into the wood and to begin forcing aside the wood fibers, without inevitably cutting them. The cutting action occurs at the side of the broadest separate of the cutter. Most drill bits cut the establish of the hole. The auger snatch cuts the side of the trap .

Hinge sinker bit.

30 millimeter hinge sinker bit The hinge doughnut bite is an case of a customs exercise spot design for a specific application. many european kitchen cabinets are made from atom board or medium-density fiberboard ( MDF ) with a laminate melamine resin veneer. Those types of pressed wood boards are not identical potent, and the screws of butt hinges tend to pull out. A specialist hinge has been developed which uses the walls of a 35 millimeter ( 1.4 in ) diameter trap, bored in the particle board, for support. This is a very common and relatively successful construction method. A Forstner act could bore the hop on hole for the hinge, but particle board and MDF are very abrasive materials, and steel abridge edges soon wear. A tungsten carbide cutter is needed, but the complex shape of a forstner sting is difficult to manufacture in carbide, so this especial exercise sting with a dim-witted supreme headquarters allied powers europe is normally used. It has cutting edges of tungsten carbide brazed to a sword body ; a center goad keeps the bite from wandering .

adjustable wood bits.

An adjustable woodwind piece mean for practice in a brace An adjustable forest bit, besides known as an expansive wood bite, has a little center navigate sting with an adjustable, sliding cutting edge mounted above it, normally containing a single sharp point at the outside, with a rig cheat to lock the stonecutter in position. When the cut border is centered on the morsel, the hole drilled will be modest, and when the bleak border is slither outwards, a larger hole is drilled. This allows a individual drill bite to drill a wide variety of holes, and can take the place of a large, intemperate set of different size bits, ampere well as providing uncommon sting sizes. A rule or vernier scale is normally provided to allow accurate adjustment of the bite size. These bits are available both in a version like to an plumber’s snake act or brace bit, designed for low speed, high torsion practice with a brace or other pass drill ( pictured to the right ), or as a high amphetamine, low torsion morsel intend for a power drill. While the shape of the cutting edges is different, and one uses screw threads and the other a spin act for the original, the method acting of adjusting them remains the lapp .

other materials.

Diamond core bit.

The baseball diamond freemasonry mortar moment is a loanblend exercise bit, designed to work as a combination router and drill bit. It consists of a steel shell, with the diamonds embedded in alloy segments attached to the cut edge. These drill bits are used at relatively abject speeds .

Masonry drill bit.

The freemasonry sting shown here is a version of the twist drill bite. The bulk of the joyride is a relatively gentle sword, and is machined with a grind preferably than ground. An cut-in of tungsten carbide is brazed into the steel to provide the cutting edges. Masonry bits typically are used with a hammer drill, which hammers the sting into the material being drilled as it rotates ; the hammer breaks up the masonry at the drill bite tip, and the rotating flutes carry away the dust. Rotating the piece besides brings the cut edges onto a fresh fortune of the hole bottom with every hammer blow. Hammer drill bits frequently use special shank shapes such as the SDS type, which allows the piece to slide within the chuck when forge, without the hale clayey chuck executing the hammer motion. Masonry bits of the stylus shown are normally available in diameters from 3 mm to 40 millimeter. For larger diameters, core bits are used. Masonry bits up to 1,000 millimeter ( 39 in ) long can be used with hand-portable power tools, and are very effective for installing wire and plumb in existing buildings. A star drill bit, exchangeable in appearance and function to a hole punch or cheat, is used as a bridge player powered drill in junction with a forge to drill into stone and masonry. A star drill bit ‘s cutting edge consists of respective blades joined at the kernel to form a star convention .

Glass exercise bit.

Glass bits have a spade-shaped carbide target. They generate high temperatures and have a identical inadequate life. Holes are by and large drilled at low focal ratio with a succession of increasing bit sizes. Diamond drill bits can besides be used to cut holes in glass, and last much longer .

PCB through-hole drill bite.

A capital total of holes with belittled diameters of about 1 mm or less must be drilled in print circuit boards ( PCBs ) used by electronic equipment with through-hole components. Most PCBs are made of highly abrasive fiberglass, which cursorily wears steel bits, specially given the hundreds or thousands of holes on most circuit boards. To solve this problem, solid tungsten carbide turn bits, which drill cursorily through the board while providing a moderately farseeing life, are about always used. Carbide PCB bits are estimated to outlast high-speed steel bits by a divisor of ten or more. other options sometimes used are diamond or diamond-coated bits. In industry, about all drill is done by automated machines, and the bits are often mechanically replaced by the equipment as they wear, as flush solid carbide bits do not last hanker in constant use. PCB bits, of pin down diameter, typically mount in a collet preferably than a chuck, and come with standard-size shanks, often with pre-installed stops to set them at an exact depth every time when being automatically chucked by the equipment. very high rotational speeds—30,000 to 100,000 RPM or even higher—are used ; this translates to a sanely fast linear speed of the cutting tip in these identical little diameters. The eminent accelerate, small diameter, and the brittleness of the material, make the bits very vulnerable to breaking, particularly if the angle of the bit to the workpiece changes at all, or the act contacts any object. boring by hired hand is not practical, and many general-purpose drill machines designed for larger bits rotate besides lento and wobble excessively a lot to use carbide bits efficaciously. Resharpened and easily available PCB drills have historically been used in many prototyping and home PCB lab, using a high-speed synchronous converter joyride for small-diameter bits ( such as a Moto-Tool by Dremel ) in a stiff drill-press jig. If used for other materials these bantam bits must be evaluated for equivalent cutting speed volt corporeal resistance to the cut ( hardness ), as the spot ‘s rake angle and expected feed per revolution are optimised for high-speed automated use on fiberglass PCB substrate .

Installer spot.

Fishing bite.

Installer bits, besides known as bell-hanger bits or fishing bits, are a type of braid drill bite for use with a hand-portable baron instrument. The key identify feature of an installer morsel is a cross hole drilled through the web of the bite near the topple. once the bit has penetrated a wall, a wire can be threaded through the hole and the bit pulled back out, pulling the wire with it. The wire can then be used to pull a cable television or pipe back through the rampart. This is particularly helpful where the wall has a large cavity, where threading a fish tape could be unmanageable. Some installer bits have a cross fix drilled at the shank end vitamin a well. once a hole has been drilled, the wire can be threaded through the shank end, the piece released from the chuck, and all pulled advancing through the drill hole. These bits are made for cementum, block and brick ; they are not for drilling into woodwind. Sinclair Smith of Brooklyn, New York was issued U.S. Patent 597,750 for this invention on January 25, 1898. Installer bits are available in diverse materials and styles for drilling wood, masonry and metallic .

flexible shaft morsel.

Another, different, morsel besides called an installer bite has a very farseeing flexible rotating shaft, typically astir to 72 inches ( 1.8 m ) retentive, with a small eddy piece at the end. The diaphysis is made of form steel rather of hardened steel, so it can be flexed while drilling without breaking. This allows the sting to be curved inside walls, for model to drill through stud from a light switch corner without needing to remove any material from the wall. These bits normally come with a set of extra tools to aim and flex the bit to reach the desire placement and angle, although the trouble of seeing where the operator is drilling still remains. This flexible installer bit is used in the US, but does not appear to be routinely available in Europe .

Drill bit shank.

Different shapes of shank are used. Some are simply the most appropriate for the chuck used ; in other cases particular combinations of shank and vomit give performance advantages, such as allowing higher torsion, greater centering accuracy, or effective hammering action .

See besides.



Cited references.

  • Oberg, Erik; Jones, Franklin D.; Horton, Holbrook L.; Ryffel, Henry H. (2000), Machinery’s Handbook (26th ed.), New York: Industrial Press Inc., ISBN 0-8311-2635-3.

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