Lip and spur drill bits 10.5 mm lip and spur bit The lip and spur drill bit is a variation of the twist drill bit which is optimized for drilling in wood. It is also called the brad point bit or dowelling bit.
Conventional twist drill bits tend to wander when presented to a flat workpiece. For metalwork, this is countered by drilling a pilot hole with a spotting drill bit. In wood, the lip and spur drill bit is another solution: The centre of the drill bit is given not the straight chisel of the twist drill bit, 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.
Metals are typically isotropic, and an ordinary twist drill bit shears the edges of the hole cleanly. Wood drilled across the grain has long strands of wood fiber. 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 maximizes the chance that the fibers 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 drill bits in a hand drill, where the hole axis is not maintained throughout the operation, have a tendency to smear the edges of the hole through side friction as the drill bit vibrates.
In metal, the lip and spur drill bit is confined to drilling only the thinnest and softest sheet metals in a drill press. The bits have an extremely fast cutting tool geometry: no point angle and a large (considering the flat cutting edge) lip angle causes the edges to take a very aggressive cut with relatively little point pressure. This means these bits tend to bind in metal; given a workpiece of sufficient thinness, they have a tendency to punch through and leave the bit's cross-sectional geometry behind.
Lip and spur drill bits are ordinarily available in diameters from 3 mm (1/8") to 16 mm (5/8").
Burrout Brad Point BIt These high performance drills made from Hi-Moly tool steel will cut holes in wood or plastics and leave no burr. They will also drill splinter free holes in wood. The special BURROUT™ point cuts at the circumference of the hole to avoid the break through burr problems common with standard point drills. When drilling into higher tensile strength metals such as cold rolled steel; a small pilot hole may prove helpful since the center spur does not cut aggressively.
Wood spade bits Spade bits are used for rough boring in wood. They tend to cause splintering when they emerge from the workpiece. They are flat, with a centering point and two cutters. The cutters often are equipped with spurs in an attempt to ensure a cleaner hole. With their small shank diameters relative to their boring diameters, spade bit 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 bit. Intended for high speed use, they are used with electric hand drills. Spade bits are also sometimes referred to as "paddle bits."
Spoon bits Spoon bits consist of a grooved shank with a point shaped somewhat like the bowl of a spoon, with the cutting edge on the end. The more common type is like a gouge bit that ends in a slight 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 boring or reaming holes in the seats and arms of chairs. Their design is ancient, going back to Roman times. Spoon bits have even been found in Viking excavations. Modern spoon bits are made of hand-forged carbon steel, carefully heat-treated and then hand ground to a fine edge.
Spoon bits are the traditional boring 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 angle of the hole can be adjusted. This is very important in chairmaking, because all the angles are usually eyeballed. Another advantage is that they do not have a lead screw, so they can be drilled successfully in a chair leg pretty much without having the lead screw peek out the other side.
When reaming a pre-bored straight-sided hole, the spoon bit is inserted into the hole and rotated in a clockwise direction with a carpenters' brace until the desired taper is achieved. When boring into solid wood, the bit should be started in the vertical position; after a "dish" has been created and the bit has begun to "bite" into the wood, the angle of boring can be changed by tilting the brace a bit out of the vertical. Holes can be drilled precisely, cleanly and quickly in any wood, at any angle of incidence, with total control of direction and the ability to change that direction at will.
Parallel spoon bits are used primarily for boring holes in the seat of a Windsor chair to take the back spindles, or similar round-tenon work when assembling furniture frames in green woodworking work.
The spoon bit may be honed by using a slipstone on the inside of the cutting edge; the outside edge should never be touched.
Forstner bits 25 mm (1") Forstner bit Another Forstner bit Forstner bits, named after their inventor, Benjamin Forstner, 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 glued 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. Unlike most other types of drill bits, they are not practical to use as hand tools.
The bit includes a center point which guides it throughout the cut (and incidentally spoils the otherwise flat bottom of the hole). The cylindrical cutter around the perimeter shears the wood fibers at the edge of the bore, and also helps guide the bit into the material more precisely. The tool in the image has a total of two cutting edges in this cylinder. Forstner bits have radial cutting edges to plane off the material at the bottom of the hole. The bit in the image has two radial edges. Other designs may have more. Forstner bits have no mechanism to clear chips from the hole, and therefore must be pulled out periodically.
Sawtooth bits are also available, which include many more cutting edges to the cylinder. These cut faster, but produce a more ragged hole. They have advantages over Forstner bits when boring into end grain.
Bits are commonly available in sizes from 8 mm (5/16") to 50 mm (2") diameter. Sawtooth bits are available up to 100 mm (4") diameter.
Center bits The center bit is optimized for drilling in wood with a hand brace. Many different designs have been produced.
The center of the bit is a tapered screw thread. This screws into the wood as the bit 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. The radial cutting edges remove a slice of wood of thickness equal to the pitch of the central screw for each rotation of the bit. 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 fibers of the wood, as in the lip and spur drill bit. A radial cutting edge planes the wood from the base of the hole. In this version, there is minimal or no spiral to remove chips from the hole. The bit must be periodically 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 central screw tends to pull out, or to split the wood along the grain, and the radial edges have trouble cutting through the long wood fibers.
Center bits are made of relatively soft steel, and can be sharpened with a file.
Auger bits The cutting principles of the auger bit are the same as those of the center bit above. The auger adds a long deep spiral flute for effective chip removal.
Two styles of auger bit are commonly used in hand braces: the Jennings or Jennings-pattern bit has a self-feeding screw tip, two spurs and two radial cutting edges. This bit has a double flute starting from the cutting edges, and extending several inches up the shank of the bit, for waste removal. This pattern of bit was developed by Russell Jennings in the mid-19th century.
The diameter of auger bits for hand braces is commonly expressed by a single number, indicating the size in 16ths of an inch. For example, #4 is 4/16 or 1/4" (6 mm), #6 is 6/16 or 3/8" (9 mm), #9 is 9/16" (14 mm), and #16 is 16/16 or 1" (25 mm). Sets commonly consist of #4-16 or #4-10 bits.
Gimlet bits 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 (1/4") diameter.
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 fibers, without necessarily cutting them. The cutting action occurs at the side of the broadest part of the cutter. Most drill bits cut the base of the hole. The gimlet bit cuts the side of the hole.
A Forstner bit could bore the mounting hole for the hinge, but particle board and MDF are very abrasive materials, and steel cutting edges soon wear. A tungsten carbide cutter is needed, but making a tungsten carbide Forstner bit is impractical, so this special drill bit is commonly used. It has cutting edges of tungsten carbide brazed to a steel body; a center spur keeps the bit from wandering.
Source
http://en.wikipedia.org/wiki/Drill_bit#Wood_drill_bitshttps://www.americanmadedrillbits.com/tech-specs/
Conventional twist drill bits tend to wander when presented to a flat workpiece. For metalwork, this is countered by drilling a pilot hole with a spotting drill bit. In wood, the lip and spur drill bit is another solution: The centre of the drill bit is given not the straight chisel of the twist drill bit, 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.
Metals are typically isotropic, and an ordinary twist drill bit shears the edges of the hole cleanly. Wood drilled across the grain has long strands of wood fiber. 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 maximizes the chance that the fibers 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 drill bits in a hand drill, where the hole axis is not maintained throughout the operation, have a tendency to smear the edges of the hole through side friction as the drill bit vibrates.
In metal, the lip and spur drill bit is confined to drilling only the thinnest and softest sheet metals in a drill press. The bits have an extremely fast cutting tool geometry: no point angle and a large (considering the flat cutting edge) lip angle causes the edges to take a very aggressive cut with relatively little point pressure. This means these bits tend to bind in metal; given a workpiece of sufficient thinness, they have a tendency to punch through and leave the bit's cross-sectional geometry behind.
Lip and spur drill bits are ordinarily available in diameters from 3 mm (1/8") to 16 mm (5/8").
Burrout Brad Point BIt These high performance drills made from Hi-Moly tool steel will cut holes in wood or plastics and leave no burr. They will also drill splinter free holes in wood. The special BURROUT™ point cuts at the circumference of the hole to avoid the break through burr problems common with standard point drills. When drilling into higher tensile strength metals such as cold rolled steel; a small pilot hole may prove helpful since the center spur does not cut aggressively.
Wood spade bits Spade bits are used for rough boring in wood. They tend to cause splintering when they emerge from the workpiece. They are flat, with a centering point and two cutters. The cutters often are equipped with spurs in an attempt to ensure a cleaner hole. With their small shank diameters relative to their boring diameters, spade bit 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 bit. Intended for high speed use, they are used with electric hand drills. Spade bits are also sometimes referred to as "paddle bits."
Spoon bits Spoon bits consist of a grooved shank with a point shaped somewhat like the bowl of a spoon, with the cutting edge on the end. The more common type is like a gouge bit that ends in a slight 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 boring or reaming holes in the seats and arms of chairs. Their design is ancient, going back to Roman times. Spoon bits have even been found in Viking excavations. Modern spoon bits are made of hand-forged carbon steel, carefully heat-treated and then hand ground to a fine edge.
Spoon bits are the traditional boring 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 angle of the hole can be adjusted. This is very important in chairmaking, because all the angles are usually eyeballed. Another advantage is that they do not have a lead screw, so they can be drilled successfully in a chair leg pretty much without having the lead screw peek out the other side.
When reaming a pre-bored straight-sided hole, the spoon bit is inserted into the hole and rotated in a clockwise direction with a carpenters' brace until the desired taper is achieved. When boring into solid wood, the bit should be started in the vertical position; after a "dish" has been created and the bit has begun to "bite" into the wood, the angle of boring can be changed by tilting the brace a bit out of the vertical. Holes can be drilled precisely, cleanly and quickly in any wood, at any angle of incidence, with total control of direction and the ability to change that direction at will.
Parallel spoon bits are used primarily for boring holes in the seat of a Windsor chair to take the back spindles, or similar round-tenon work when assembling furniture frames in green woodworking work.
The spoon bit may be honed by using a slipstone on the inside of the cutting edge; the outside edge should never be touched.
Forstner bits 25 mm (1") Forstner bit Another Forstner bit Forstner bits, named after their inventor, Benjamin Forstner, 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 glued 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. Unlike most other types of drill bits, they are not practical to use as hand tools.
The bit includes a center point which guides it throughout the cut (and incidentally spoils the otherwise flat bottom of the hole). The cylindrical cutter around the perimeter shears the wood fibers at the edge of the bore, and also helps guide the bit into the material more precisely. The tool in the image has a total of two cutting edges in this cylinder. Forstner bits have radial cutting edges to plane off the material at the bottom of the hole. The bit in the image has two radial edges. Other designs may have more. Forstner bits have no mechanism to clear chips from the hole, and therefore must be pulled out periodically.
Sawtooth bits are also available, which include many more cutting edges to the cylinder. These cut faster, but produce a more ragged hole. They have advantages over Forstner bits when boring into end grain.
Bits are commonly available in sizes from 8 mm (5/16") to 50 mm (2") diameter. Sawtooth bits are available up to 100 mm (4") diameter.
Center bits The center bit is optimized for drilling in wood with a hand brace. Many different designs have been produced.
The center of the bit is a tapered screw thread. This screws into the wood as the bit 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. The radial cutting edges remove a slice of wood of thickness equal to the pitch of the central screw for each rotation of the bit. 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 fibers of the wood, as in the lip and spur drill bit. A radial cutting edge planes the wood from the base of the hole. In this version, there is minimal or no spiral to remove chips from the hole. The bit must be periodically 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 central screw tends to pull out, or to split the wood along the grain, and the radial edges have trouble cutting through the long wood fibers.
Center bits are made of relatively soft steel, and can be sharpened with a file.
Auger bits The cutting principles of the auger bit are the same as those of the center bit above. The auger adds a long deep spiral flute for effective chip removal.
Two styles of auger bit are commonly used in hand braces: the Jennings or Jennings-pattern bit has a self-feeding screw tip, two spurs and two radial cutting edges. This bit has a double flute starting from the cutting edges, and extending several inches up the shank of the bit, for waste removal. This pattern of bit was developed by Russell Jennings in the mid-19th century.
The diameter of auger bits for hand braces is commonly expressed by a single number, indicating the size in 16ths of an inch. For example, #4 is 4/16 or 1/4" (6 mm), #6 is 6/16 or 3/8" (9 mm), #9 is 9/16" (14 mm), and #16 is 16/16 or 1" (25 mm). Sets commonly consist of #4-16 or #4-10 bits.
Gimlet bits 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 (1/4") diameter.
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 fibers, without necessarily cutting them. The cutting action occurs at the side of the broadest part of the cutter. Most drill bits cut the base of the hole. The gimlet bit cuts the side of the hole.
A Forstner bit could bore the mounting hole for the hinge, but particle board and MDF are very abrasive materials, and steel cutting edges soon wear. A tungsten carbide cutter is needed, but making a tungsten carbide Forstner bit is impractical, so this special drill bit is commonly used. It has cutting edges of tungsten carbide brazed to a steel body; a center spur keeps the bit from wandering.
Source
http://en.wikipedia.org/wiki/Drill_bit#Wood_drill_bitshttps://www.americanmadedrillbits.com/tech-specs/