Drilling down into a deep discussion
A drill bit is a cutting tool designed to bore cylindrical holes in a variety of materials. Bits are secured into a drill, either mechanized or manual, which provides the rotational and axial force required to cut through the material. Some bits require additional axial pressure to cut through the desired material. Hammer drills provide this additional force by repeatedly hammering the drill bit down into the material while rotating the bit to clear debris.
Drill bits come in a variety of sizes, materials and configurations. They are usually grouped according to the materials that they are designed to cut and by the materials that ...
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Drilling down into a deep discussion
A drill bit is a cutting tool designed to bore cylindrical holes in a variety of materials. Bits are secured into a drill, either mechanized or manual, which provides the rotational and axial force required to cut through the material. Some bits require additional axial pressure to cut through the desired material. Hammer drills provide this additional force by repeatedly hammering the drill bit down into the material while rotating the bit to clear debris.
Drill bits come in a variety of sizes, materials and configurations. They are usually grouped according to the materials that they are designed to cut and by the materials that comprise them.
Below we list the most common types of drill bits:
Twist Drill Bits: twist drill bits are the most common type of drill bit and can be used to cut through many common materials. Metal, plastic, wood and stone drill bits may be of this type.
Screw Extractor / Left Hand Drill Bits: screw extractor drill bits are also referred to as left hand drill bits since they are meant to be rotated in a counter clockwise direction instead of the clockwise motion of a standard drill bit. As the drill bit is driven into a damaged screw or drill bit, the counter clockwise rotation of the bit draws the damaged item back out of the hole it created. Essentially, left hand drill bits are used to drill objects out of a given material instead of into it.
Countersink Drill Bits: countersink drill bits are cone shaped bits that are best used as de-burring tools to remove burrs from a previous machining operation for cosmetic and safety reasons. Countersink drill bits can also be built on to the top end of twist drill bits to provide a recessed hole for the head of a screw.
Lip and Spur Drill Bits: lip and spur drill bits are also referred to as brad point or dowelling bits and are specifically designed for use in wood or other soft materials. They are built to combat the tendency of drill bits to wander when used on a flat surface. The business end of the drill bit has spurs that dig into the wood to fight slippage.
Spade Drill Bits: spade drill bits are meant for boring rough holes in wood and tend to cause splintering on the backside of the hole being drilled.
Forstner Drill Bits: forstner drill bits (named after their inventor Benjamin Forstner) are designed to bore precise, flat bottomed holes in wood.
Auger Drill Bits: auger drill bits are designed to bore long holes through wood and use a smaller screw-like point to pull the drill bit through the wood. A long deep helix along the shaft of the bit is used to remove wood chips from the hole.
Masonry Drill Bits: masonry drill bits are generally used with a hammer drill to drill through stone, brick and masonry. The bulk of the bit is made of a relatively soft steel core while an insert of harder material (generally tungsten carbide) makes up the cutting edge of the tool. This drill bit functions by crushing the material at the end of the drill bit and drawing the resulting debris out of the hole through the flutes of the drill bit body.
Holesaw Drill Bits: holesaw drill bits are used to make large bore holes in relatively thin materials such as wooden doors or plastic. A circular form with teeth cuts the hole and is mounted on a central twist drill bit which acts as a guide to center the bit.
Drill bits are manufactured using a variety of materials depending upon what materials they are being used to drill into. Using a common wood drill bit to bore a hole into concrete can be an interesting, destructive and painful experience. Ensure that your drill bit is appropriate to the material you wish to make holes in.
Common drill bit materials are listed below:
Low Carbon Steel: this is the common wooden drill bit.
High Carbon Steel: are used for both wood and metal but are vulnerable to heat which causes wear, breakage and a soft cutting edge.
High Speed Steel: is a specialized form of steel that is much more resistant to heat and can therefore be used at higher drilling speed and a wider range of materials.
Cobalt Steel Alloys: similar to high speed steel, cobalt steel alloy drill bits can withstand even greater heat levels but are more brittle.
Tungsten Carbide: is extremely hard and can drill into virtually anything. It is, however, very expensive and quite brittle and is therefore used primarily as coatings or smaller pieces attached to the tip of a cheaper material.
Polycrystalline Diamond: is one of the hardest materials in the world and is comprised of diamond particles bonded to a tungsten carbide support. They are generally used to drill through highly abrasive materials such as aluminum alloys and carbon fiber reinforced plastics in the automotive and aerospace industries.
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