Boring, in this sense, is the process of drilling a hole into the solid Earth. The most basic principle involved is the cutting of rock and removal of the broken material (cuttings) from the hole. A drill is a tool with a rotating drill bit used for drilling holes in various materials. ...

Boring is used for a wide variety of applications in geology, agriculture, hydrology, civil engineering, and oil and natural gas industries. Today, most drilling is done in order to either 1) return samples of the rock through which the drill passes, 2) access rocks from which material can be extracted, 3) access rocks which can then be measured or 4) provide access to rock for purposes of providing engineering support.
The drilling mechanisms outlined below differ mechanically in terms of the machinery used, but also in terms of the method by which drill cuttings are removed from the cutting face of the drill and returned to surface. Geology (from Greek γη- (ge-, the earth) and λογος (logos, word, reason)) is the science and study of the Earth, its composition, structure, physical properties, history, and the processes that shape it. ... Water covers 70% of the Earths surface. ... Engineering applies scientific and technical knowledge to solve human problems. ... Oil is a generic term for organic liquids that are not miscible with water. ... Natural gas (commonly refered to as gas in many countries, but note that gas is also an American and Canadian shortening of gasoline) is a gaseous fossil fuel consisting primarily of methane. ...

Drill Types

There are a variety of drill mechanisms which can be used to sink a borehole into the ground. Each has its advantages and disadvantages, in terms of the depth to which it can drill, the type of sample returned, the costs involved and penetration rates achieved. There are two basic types of drills - ones which produce rock chips or ones which produce core.

Auger Drilling
Auger drilling is achieved by means of a helical screw which is driven into the ground with rotation; the earth is lifted up the borehole by the blade of the screw. Auger drilling is used for well drilling, fence construction, soil engineering and geochemistry reconnaissance work in exploration for mineral deposits. In some cases, mine shafts are dug with auger drills. Small augers can be mounted on the back of a utility truck, with large augers used for sinking piles for bridge foundations.
Auger drilling is restricted to generally soft, unconsolidated material or weak, weathered rock. It is cheap and fast. For the Scottish football team, see Motherwell F.C. The Whole Earth Lectronic Link (or The WELL) is one of the oldest virtual communities still online. ... A fence is a freestanding structure designed to restrict or prevent movement across a boundary. ... Soil is unconsolidated rock particles mixed with organic matter from plant decay. ... Engineering applies scientific and technical knowledge to solve human problems. ... The field of geochemistry involves study of the chemical composition of the Earth and other planets, chemical processes and reactions that govern the composition of rocks and soils, and the cycles of matter and energy that transport the Earths chemical components in time and space, and their interaction with... This article is about minerals in the geologic sense; for nutrient minerals see dietary mineral; for the band see Mineral (band). ... Mine can refer to a number of things: Mines are tunnels used in mining for extraction of resources. ...

Air Core Drilling
Air core drilling and related methods use hardened steel or tungsten blades to bore a hole into rock. The drill bit has three blades arranged around the bit head, which cut the rock. The rods are hollow and contain an inner tube which sits inside the hollow outer rod barrel. The drill cuttings are removed by injection of compressed air into the hole via the hollow inner rod. The cuttings are then blown back to surface via the outer space inside the barrel where they are collected if needed, or discarded. Drilling continues with the addittion of rods to the top of the drill string. Air core drilling can occasionally produce small chunks of cored rock.
This method of drilling is used to drill the weathered regolith, as the drill rig and steel or tungsten blades cannot penetrate fresh rock. where possible, air core drilling is preferred over RAB drilling as it provides a more representative sample. Air core drilling can achieve depths approaching 200 metres in good conditions as the cuttings are removed inside the rods and are less likely to clog. However, this method is more costly and slower than RAB.

Regolith is a layer of loose, heterogeneous material covering solid rock. ...

Percussion Rotary Air Blast Drilling (RAB)
RAB drilling is used most frequently in the mineral exploration industry. The drill uses a pneumatic reciprocating piston to energetically drive a heavy drill bit into the rock. The drill bit is hollow, solid steel and has ~20mm thick tungsten rods protruding from the steel matrix as 'buttons'. The tungsten buttons are the cutting face of the bit.
The cuttings are blown up the outside of the rods and collected at surface.
RAB drilling is used primarily for mineral exploration, water bore drilling and blast-hole drilling in mines, as well as for other applications such as engineering, etc. RAB produces lower quality samples because the cuttings are blown up the outside of the rods and can be contaminated from contact with other rocks. RAB drilling rarely achieves more than 150 metres depth as encountering water rapidly clogs the outside of the hole with debris, precluding removal of drill cuttings from the hole.

Reverse Circulation (RC) Drilling
RC drilling is similar to air core drilling, in that the drill cuttings are returned to surface inside the rods. The drilling mechanism is a penumatic reciprocating piston driving a tungsten-steel drill bit. RC drilling utilises much larger rigs and machinery and depths of up to 500m are routinely achieved. RC drilling ideally produces dry rock chips, as large air compressors are used to dry the rock out ahead of the advancing drill bit. RC drilling is slower and costlier but achieves better penetration than RAB or air core drilling; it is cheaper than diamond coring and is thus preferred for most mineral exploration work.

Compressor has several meanings: A gas compressor is a mechanical device that takes in a gas and increases its pressure by squeezing a volume of it into a smaller volume. ...

Diamond core drilling
Diamond core drilling utilises an annular diamond-impregnated drill bit attached to the end of hollow drill rods to cut a cylindrical core of solid rock. The diamonds used are fine to microfine industrial grade diamonds. They are set within a matrix of varying hardness, from brass to high-grade steel. Matrix hardness, diamond size and dosing can be varied according to the rock which must be cut. Holes within the bit allow water to be delivered to the cutting face. This provides three essential functions; lubrication, cooling, and removal of drill cuttings (in this case, fine slurry), without which drilling cannot continue.
Core is retrieved via use of a core lifter a hollow tube inserted into the core barrel which slides over the core as it is cut. A tool is sent down and locks on to the core lifter, and pulls the lifter and its core to surface.

Oil Well Drilling
Oil well drilling utilised roller bits to wear away at the cutting face. This is preferred because there is no need to return samples to surface for assay as the objective is to strike a formation containing oil or natural gas. Sizeable machinery is used, enabling depths of several kilometres to be penetrated.

History

Until the advent of internal combustion engines in the late 19th century, the primary method for drilling rock involved muscle power be it human or animal. Rods were turned by hand, using clamps attached to the rod. The rope and drop method, invented in China utilised a steel rod or piston raised and dropped vertically via a rope. Mechanised versions of this persisted until ~1970, utilising a cam to rapidly raise and drop what, by then, was a steel cable.

In the 1970's, outside of the oil and gas industry, roller bits utilising mud circulation were replaced by the first efficient pneumatic reciprocating piston RC drills, and became essentially obsolete for the majority of shallow drilling, and are now only used in certain situations where rocks preclude other methods. RC drilling proved much faster and efficient, and continues to improve with better metallurgy deriving harder, more durable bits, and compressors delivering higher air pressures at higher volumes, enabling deeper and faster penetration. Diamond drilling has remained essentially unchanged since its inception. Metallurgy is a domain of materials science and of materials engineering that studies the physical and chemical behavior of metallic elements and their mixtures, which are called alloys. ...

Limits of the technology

Drill technology has advanced steadily since the 19th century. However, there are several basic limiting factors which will determine the depth to which a bore hole can be sunk.
All holes must maintain outer diameter; the diameter of the hole must remain wider than the diameter of the rods or the rods cannot turn in the hole and progress cannot continue. Friction caused by rotation will tend to reduce the outside diameter of the drill bit. This applies to all drilling methods, except that in diamond core drilling and oil well drilling the use of thinner rods and casing may permit the hole to continue. Casing is simply a hollow sheath which protects the hole against collapse during drilling, and is often made of metal or PVC. Often diamond holes will start off at a large diameter and when outside diameter is lost, thinner rods put down inside casing to continue, until finally the hole becomes too thin. Alternatively, the hole can be reamed.
For percussion techniques, the main limitation is air pressure. Air must be delivered to the piston at sufficient pressure to activate the reciprocating action, and in turn drive the head into the rock with sufficient strength to fracture and pulverise it. With depth, volume is added to the in-rod string, requiring larger compressors to achieve operational pressures. Secondly, groundwater is ubiquitous, and increases in pressure with depth in the ground. The air inside the rod string must be pressurised enough to overcome this water pressure at the bit face. Then, the air must be able to carry the rock fragments to surface. This is why depths in excess of 500m for reverse circulation drilling is rarely achieved, because the cost is prohibitive and approaches the threshold at which diamond core drilling is more economic. Diamond drilling can routinely achieve depths in excess of 1,200m. In cases where money is no issue, extreme depths have been achieved because there is no requirement to overcome water pressure. However, circulation must be maintained to return the drill cuttings to surface, and more importantly to maintain cooling and lubrication of the cutting surface. Without sufficient lubrication and cooling, the matrix of the drill bit will soften. While diamond is the hardest substance known to man at 10 on the mohs hardness scale, it must remain firmly in the matrix to achieve cutting. Weight on bit, the force exerted on the cutting face of the bit by the drill rods in the hole above the bit, must also be monitored.
One final phenomenon limiting drilling only became apparrent during deep drilling of an attempted Mohole. PVC may refer to the following: The chemical compound polyvinyl chloride Irregular heartbeat: premature ventricular contraction In frame relay, ATM and X.25 a permanent virtual circuit This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... Groundwater is water which may be flowing within aquifers below the water table. ... Pressure (symbol: p) is the force per unit area acting on a surface in a direction perpendicular to that surface. ... Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. ...

Causes of deviation

All bore holes deviate from their plan. This is because of the torque of the turning bit working against the cutting face; because of the flexibility of the steel rods and especially the screw joints; because of reaction to foliation and structure within the rock, and of refraction as the bit moves from different rock units of varying [[[rheology]]. Additionally, inclined holes will deviate upwards usually because the drill rods will lay against the bottom of the bore, causing the drill bit to be slightly inclined versus true. It is because of deviation that drill holes must be surveyed if deviation will impact on the usefulness of the information returned. In mathematics, informally speaking, a foliation is a kind of clothing worn on a manifold, cut from a stripy fabric. ... The soda straw appears to be broken, due to refraction of light rays as they emerge into the air. ...

The Mohole

In the 1970's and early 1980's the USSR attempted to drill a hole through the crust, to sample the Mohorivicic Discontinuity. The deepest hole ever drilled failed not because of lack of money or time, but because of the physics of rocks within the crust. The hole achieved approximately 12,000 metres depth, a depth at which rock begins to act more like a plastic solid than a rigid solid. The rock also approached temperatures of several hundred degrees celsius, requiring that the drilling fluid was refrigerated before being sent to the cutting face of the drill. As the drill bits burnt out and were removed for replacement, the hole simply flowed closed, and the rock had to be re-drilled. Due to the temperature, the drill bits burnt out before achieving any headway. The hole was scrapped. Earth cutaway from core to exosphere. ... Plastic bottles for recycling Plastic is a term that covers a range of synthetic or semisynthetic polymerization products. ...

Boring, 1911 Encyclopedia Brittanica

Boring allows the ascertaining of the nature, thickness and extent of the various geological formations underlying the surface of the Earth. Among the purposes for which boring is specifically employed are: (1) prospecting or searching for mineral deposits; (2) sinking petroleum, natural gas, artesian or salt wells; (3) determining the depth below the surface of bedrock or other firm substratum, together with the character of the overlying materials, preparatory to mining or civil engineering operations; (4) carrying on geological or other scientific explorations. Prospecting by boring is practiced most successfully in the case of mineral deposits of large area, which are nearly horizontal, or at least not highly inclined; such as deposits of coal, iron, lead and salt. Wide, flat beds of such minerals may be pierced at any desired number of points. The depth at which each hole enters the deposit and the thickness of the mineral itself are readily ascertained, so that a map may be constructed with some degree of accuracy. Samples of the mineral are also secured, furnishing data as to the value of the deposit. While boring is sometimes adopted for prospecting irregular and steeply inclined mineral deposits of small area, the results are obviously less trustworthy than under the conditions named above, and may be actually misleading unless a large number of holes are bored. Incidentally, boreholes supply information as to the character and depth of the valueless depositions of earth or rock overlying the mineral deposit. Such data assist in deciding upon the appropriate method for, and in estimating the cost of, sinking shafts or driving tunnels for the development and exploitation of the deposit. In sinking oil wells, boring serves not only for discovering the oil-bearing strata but also for extracting the oil. This industry has become of great importance in many parts of the United States, in Southern Russia and elsewhere. Interstate road cut through limestone and shale strata in eastern Tennessee In geology and related fields, a stratum (plural: strata) is a layer of rock or soil with internally consistent characteristics that distinguishes it from contiguous layers. ... Earth, also known as Terra, and (mostly in the 19th century) Tellus, is the third-closest planet to the Sun. ... This article is about minerals in the geologic sense; for nutrient minerals see dietary mineral; for the band see Mineral (band). ... Nodding donkey pumping an oil well near Sarnia, Ontario Petroleum (from Latin petra – rock and oleum – oil), crude oil, sometimes colloquially called black gold, is a thick, dark brown or greenish liquid. ... Natural gas (commonly refered to as gas in many countries, but note that gas is also an American and Canadian shortening of gasoline) is a gaseous fossil fuel consisting primarily of methane. ... Geological strata giving rise to an Artesian well An artesian aquifer is an aquifer whose water is overpressurized. ... In chemistry, salt is a term used for ionic compounds composed of positively charged cations and negatively charged anions, so that the product is neutral and without a net charge. ... Bedrock is the native consolidated rock underlying the Earths surface. ... In linguistics, a substratum is a language which influences another one while that second language supplants it. ... The El Chino Mine located near Silver City, New Mexico is an open-pit copper mine This article is about mineral extraction. ... The Falkirk Wheel in Scotland. ... Geology (from Greek γη- (ge-, the earth) and λογος (logos, word, reason)) is the science and study of the Earth, its composition, structure, physical properties, history, and the processes that shape it. ... For the scientific journal named Science, see Science (journal). ... Horizontal is an orientation relating to, or in parallel with the horizon, and thus perpendicular to the vertical. ... Coal is a fossil fuel extracted from the ground by deep mining, coal mining (open-pit mining or strip mining). ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ... General Name, Symbol, Number lead, Pb, 82 Chemical series poor metals Group, Period, Block 14, 6, p Appearance bluish white Atomic mass 207. ... DATA (Debt, AIDS, Trade, Africa) was established in 2002 by Bono (Paul Hewson) of the Rock band U2, and Bobby Shriver, along with activists from the Jubilee 2000 Drop the Debt Campaign, as an organisaton focused on Justice, not charity. ... // Rock may refer to: Geology Rock (geology), a substance composed of minerals. ... A disused railway tunnel now converted to pedestrian and bicycle use, near Houyet, Belgium A tunnel is an underground passage. ... 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. ...

Deposits of rock salt are sometimes worked through boreholes, by introducing water and pumping out the solution of brine for further treatment. The sinking of artesian wells is another application of boring. They are often hundreds, and sometimes thousands, of feet in depth. A well in St. Louis, Missouri, has a depth of 3,843 ft. Boring is useful in mines themselves for a variety of purposes, such as exploring the deposit ahead of the workings, searching for neighboring veins, and sounding the ground do approaching dangerous inundated workings. In the coal regions of Pennsylvania, boreholes are often sunk for carrying steam pipes and hoisting ropes underground at points remote from a shaft. Several of the methods of boring in soft ground are employed in connection with civil engineering operations; as for ascertaining the depth below the surface to solid rock, preparatory to excavating for and designing deep foundations for heavy structures, and for estimating the cost of large scale excavations in earth and rock. Lastly, a number of deep holes have been bored for geological exploration or for observing the increase of temperature in depth in the Earth's crust; for example, at Paruschowitz, Silesia, about 6,700 ft. deep; at Leipzig, Germany, 6,265 ft.; near Pittsburg, Pennsylvania, 5,532 ft.; and at Wheeling, West Virginia, nearly 5,000 ft. The two last mentioned were intended to obtain as complete knowledge as possible of the bituminous coal and oil-bearing formations. There are five methods of boring, by (1) earth augers, (2) drive pipes, (3) long, jointed rods and drop drill, (4) the rope system, in which the rods are replaced by rope, (5) rotary drills. The first two methods are adapted to soft or earthy soils only; the others are for rock. Sodium chloride, also known as common salt, table salt, or halite, is a chemical compound with formula NaCl. ... Water (from the Old English word wæter; c. ... Brine is water saturated or nearly saturated with salt. ... The Gateway Arch, shown here behind the Old Courthouse, is the most recognizable part of the St. ... In geology, a vein is a finite volume within a rock, having a distinct shape, filled with mono or poly mineralic crystal aggregates, which were precipitated from an (aqueous) fluid or melt. ... State nickname: The Keystone State Official languages None Capital Harrisburg Largest city Philadelphia Governor Ed Rendell (D) Senators Arlen Specter (R) Rick Santorum (R) Area  - Total  - % water Ranked 33rd 119,283 km² 2. ... In physical chemistry and in engineering, steam refers to vaporized water. ... Coils of rope used for long-line fishing A rope is a length of fibers, twisted or braided together to improve strength, for pulling and connecting. ... Look up Foundation on Wiktionary, the free dictionary Foundation may refer to: A type of makeup. ... Earth cutaway from core to exosphere. ... Prussian Silesia, 1871, outlined in yellow; Silesia at the close of the Seven Years War in 1763, outlined in cyan (areas now in Czech Republic were Austrian-ruled at that time) Silesia (-Latin, Polish: ÅšlÄ…sk, German: Schlesien, Czech: Slezsko) is a historical region in central Europe. ... Map of Germany showing Leipzig Leipzig [ˈlaiptsɪç] (Sorbian/Lusatian: Lipsk) is the largest city in the federal state (Bundesland) of Saxony in Germany. ... City nickname: The Steel City Location in the state of Pennsylvania Founded 1758 Mayor Tom Murphy (Dem) Area  - Total  - Water 151. ... Wheeling is a city located in West Virginia, in the United States. ... Bituminous coal Bituminous coal is a soft coal containing a tar-like substance called bitumen. ... An auger is a device for moving material or liquid by means of a rotating helical flighting. ... A drill is a tool with a rotating drill bit used for drilling holes in various materials. ... Soil is unconsolidated rock particles mixed with organic matter from plant decay. ...

1. Earth augers comprise spiral and pod augers. The ordinary spiral auger resembles the wood auger commonly used by carpenter]s. It is attached to the rod or stem by a socket joint, successive sections of rod being added as the hole is deepened. The auger is rotated by means of horizontal levers, clamped to the rod—by hand for holes of small diameter (2 to 6 in.), the larger sizes (8 to 16 in.) by machine. Clayey, cohesive soils, containing few stones, are readily bored; stony ground with difficulty. The operation of the auger is intermittent. After a few revolutions it is raised and emptied, the soil clinging between the spirals. For sandy, non-cohesive soils, the auger may be encircled by a close-fitting sheet-iron cylinder to prevent the soil from falling out. Pod augers generally vary in diameter from 8 to 20 in. A common form consists of two curved iron plates, one attached to the rod rigidly, the other by hinge and key. A tree trunk as found at the Veluwe, The Netherlands Wood derives from woody plants, notably trees but also shrubs. ... A carpenter is a skilled craftsman who performs carpentry -- a wide range of woodworking that includes constructing buildings, furniture, and other objects out of wood. ... Quaternary clay in Estonia. ... Patterns in the sand Sand is an example of a class of materials called granular matter. ... A hinge is a mechanical device that connects two solid objects, allowing rotation between them. ...

By being turned through a few revolutions the pod is filled, and is then raised and emptied. For boring in sandy soils, the open sides are closed by hinged plates. For holes of large diameter earth augers are handled with the aid of a light derrick. A derrick is a lifting device composed of one mast or pole which is hinged freely at the bottom. ...

2. Drive pipes are widely used, both for testing the depth and character of soft material overlying solid rock and as a necessary preliminary to rock boring, when some thickness of surface soil must first be passed through. In its simplest form, the drive pipe consists of one or more lengths of wrought iron pipe, open at both ends and from 2 in. to 6 in. diameter. When of small size the pipe is driven by a heavy hammer; for deep and large holes, a light piledriver becomes necessary. The lower end of the pipe is provided with an annular steel shoe; the upper end has a drive head for receiving the blows of the hammer. Successive lengths are screwed on as required. For shallow holes the pipe is cleaned out by a "bailer" or "sand-pump" a cylinder 4 to 6 ft. long, with a valve in the lower end. Wrought iron is a very pure form of commercial iron, having a very small carbon content. ... A claw hammer A hammer is a tool meant to deliver blows to a target, causing it to move or deform. ... A Piledriver is a professional wrestling move in which the wrestler grabs his/her opponent, turns him/her upside-down, and drops into a sitting or kneeling position, driving the victims head into the mat. ... Annular, annulate, &c. ... The old steel cable of a colliery winding tower Steel is a metal alloy whose major component is iron, with carbon being the primary alloying material. ...

It is lowered at intervals, filled by being dashed up and down, and then raised and emptied. If, after reaching some depth, the external friction prevents the pipe from sinking farther, another pipe of small diameter may be inserted and the driving continued. Drive pipes are often sunk by applying weights at the surface and slowly rotating by a lever. Two pipes are then used, one inside the other. Water is pumped down the inner pipe, thus loosening the soil, raising the debris and increasing the speed of driving. The "driven well" for water supply is an adaptation of the drive pipe and put down in the same way. In physics, friction is the non-conservative resistive force that occurs when two surfaces travel along each other when forced together. ...

3. Drill and rods have long been used in Europe and elsewhere for deep boring. In the United States it is rarely employed for depths greater than 200 or 300 ft. Wooden rods are occasionally used. For shallow holes (50 to 75 ft.) the work is done by hand, one or two crossbars being clamped to the rod. The men alternately raise and drop the drill, meanwhile slowly walking around and around to rotate the bit and so keep the hole true. The cuttings are cleaned out by a bailer, as for drive pipes. In boring by hand, the practical limit of depth is soon reached, on account of the increasing weight of the rods. For going deeper a "spring-pole" may be used. This is a tapering pole, say 30 ft. long and 5 or 6 in. diameter at the small end. It rests in an inclined position on a fulcrum set about to ft. from the butt, the latter being firmly fixed. The rods are suspended from the end of the pole, which ex-tends at a height of several feet over the mouth of the hole. A satellite composite image of Europe Europe is the worlds second-smallest continent in terms of area, covering around 10,790,000 km² (4,170,000 sq mi) or 2. ...

With the aid of the spring of the pole the strokes are produced by a slight effort on the part of the driller. Average speeds of 6 to 10 ft. per 10 hours are easily made, to depths of 200 to 250 ft. For deep boring the rod system requires a more elaborate plant. The rods are suspended from a heavy "walking beam" or lever, usually oscillated by an engine. By means of a screw-feed device, the rods, which are rotated slightly after every stroke, are gradually fed down as the hole is deepened, length after length being added. A tall derrick carries the sheaves and ropes by which the rods and tools are manipulated. The drill bit cannot be attached rigidly to the rods as in shallow boring, because the momentum of the heavy moving parts, transmitted directly to the bit as the blow is struck, would cause excessive vibration and breakage. It becomes necessary, therefore, to introduce a sliding-link joint between the rods and bit. On striking its blow, the bit comes to rest, while the rods continue to descend to the end of the stroke, the upper member of the link sliding down upon the lower. An engine is something that produces some effect from a given input. ... Drill bits are the cutters of drill tools. ... See Oscillator (disambiguation) for particular types of oscillation and oscillators. ...

Then, on the up stroke the lower link, with the bit, is raised for delivering another blow. For large holes the striking weight is, say, 800 to 1,000 lb, length of stroke 21 to 5 ft., and speed from 20 to 30 strokes per minute. By using the sliding link the cross-section and weight of the rods may be greatly reduced, the only strain being that of tension. To deliver a sharp, effective blow, however, the rods must drop with a quick stroke, which brings a heavy strain upon the operating machinery. For overcoming this difficulty, various "freefalling tools" have been devised. By these the bit is allowed to fall by gravity; the rod follows on its measured down stroke, and picks up the bit. Freefalling tools are of two classes: those by which the bit is released automatically; and those operated by a sudden twist imparted to the rod by the drillman. One of the best known of the first class is the kind freefall. The shank of the bit is gripped and released by the jaws, worked through a toggle joint by movements of the disk. In any branch of science dealing with materials and their behaviour, strain is the geometrical expression of deformation caused by the action of stress on a physical body. ... Gravity is the force of attraction between massive particles. ... Shank can refer to: A major scaffold protein that interact indirectly with both NMDA receptors and metabotropic receptors. ...

When the rod begins its downward stroke, the resistance of the water in the hole slightly raises the disk, thus opening the jaws and releasing the bit, which falls by gravity. On reaching the end of the stroke the jaws again catch the shank of the bit and raise it for delivering another blow. The Fabian freefall may be noted as an example of the second class. Tools are sometimes used for cutting an annular groove in the bottom of the hole, and raising to the surface the core so formed, for observing the character of the rock.

4. Rope and drop tools was a method long ago used in China. Because of its extensive application in the oil fields it is generally designated in the United States as the "oil well system". In its various modifications it is often employed also in general prospecting of mineral deposits and in sinking artesian, natural gas and salt wells. One of its forms deep boring it possesses the advantage of saving the large amount of time consumed in raising and lowering the rods, as required whenever the hole is to be cleaned out, or a dull bit replaced, since the tools are rapidly run up or down by means of the rope with which they are operated while drilling. The speed of rope boring is therefore but little affected by increase of depth, while with rod-boring it falls off rapidly. In its simplest form the so-called "string of tools", suspended from the rope, is composed of the bit or drill, jars and rope-socket. The jars are a pair of sliding links, similar to those used for rod-boring, jars serving a different purpose, to produce a sharp shock on the upward stroke, as the jars come together, for loosening the bit should it tend to stick fast in the hole.

A heavy bar, auger stem, is generally inserted between the jars and bit, for increasing the force of the blow. The weight of another bar above the jars, a sinker-bar, keeps the rope taut. The length of stroke and feed are regulated by the "temper-screw", a feed device resembling that used for rod boring. Clamped to it is the drill rope, which is let out at intervals, as the hole is deepened. The bits usually range from 3 to 8 in. diameter, the speed of boring being generally between 20 and 40 ft. per 24 hours, according to the kind of rock. A great variety of special "fishing tools" are made, for use in case of breakage of parts in the hole or other accident.

5. Diamond drills can bore holes in any direction, from vertically downward to vertically upward. It has the further advantage of making an annular hole from which is obtained a core, furnishing a practically complete cross-section of the strata penetrated; the thickness and character of each stratum are shown, together with its depth below the surface. Thus, the diamond drill is peculiarly well adapted for prospecting mineral deposits from which samples are desired. Diamond is a Featured Article A scattering of round-brilliant cut diamonds shows off the many reflecting facets. ...

The first practical application of diamonds for drilling in rock was made in 1863 by Professor Rudolph Leschot, a civil engineer of Paris. The apparatus consists essentially of a line of hollow rods, coupled by screw joints, an annular steel bit or crown, set with diamonds being attached to the lower end. By means of a small engine on the surface the rods are rapidly rotated and fed down automatically as the hole is deepened. The speed of rotation is from 300 to 800 revolutions per minute, depending on the character of the rock and diameter of the bit. While boring, a stream of water is forced down the hollow rods by a pump, passing back to the surface through the annular space between the rods and the walls of the drill hole. The cuttings are thus carried to the surface, leaving the bottom of the hole clean and unobstructed. For recovering the core and inspecting the bit and diamonds, the rods are raised at every 3 to 8 ft. of depth. This is done by a small drum and rope, operated by the driving engine. Diamond drills of standard designs bore holes from 1 to 1 15/16 in. diameter, yielding cores of 1 1/4 to 1 9/16 in. diameter, and are capable of reaching depths of a few hundred to 4,000 ft. or more. They require from 8 to 30 boiler horsepower. Large machines will bore shallower holes up to 6, 9 or even 12 in. diameter. 1863 is a common year starting on Thursday. ... The Eiffel Tower has become a symbol of Paris throughout the world. ... Diamond is a Featured Article A scattering of round-brilliant cut diamonds shows off the many reflecting facets. ... Revolutions per minute (abbreviated rpm, RPM or r/min) is a unit of frequency, commonly used to measure rotational speed. ... For other kinds of drums, see drum (disambiguation). ... The horsepower (hp) is the name of several non-metric units of power. ...

For operating in underground workings of mines, small and compact machines are sometimes mounted on columns. They bore 7/8 in. holes to depths of 300 to 400 ft., cores being 7/8 in. diameter. Hand-power drills are also built. In the South African gold mines several diamond drill holes from 4,500 to 5,200 ft. deep have been successfully bored. Rates of advance for core drilling to moderate depths range usually from 2 to 3 ft. per hour, including ordinary delays, though in favorable rock much higher speeds are often attained. In deep holes the speeds diminish, because of time consumed in raising and lowering the rods. If no core is desired a "solid bit" is used. The drilling then proceeds faster, as it is only necessary to raise the rods occasionally, for examining the condition of the bit. The driving engine has two inclined cylinders, coupled to a crankshaft, by which, through gearing, the drill-rod is rotated. Gold mining consists of the processes and techniques employed in the removal of gold from the ground. ... Crankshaft Continental engine marine crankshafts, 1942 Crankshaft is also the name of a comic strip about an old, curmudgeonly bus driver. ... In finance, Gearing is defined as the ratio between long-term debt to the shareholders funds on a companys balance sheet. ...

The rods are wrought iron or steel tubes, in 5 to 10 ft. lengths. For producing the feed two devices are employed, the differential screw and hydraulic cylinder. For the differential feed, the engine has a hollow left-hand threaded screw-shaft, to which the rods are coupled. This shaft is driven by a spline and bevel gearing and is supported by a threaded feed-nut, carried in the lower bearing. Geared to the screw-shaft is a light counter-shaft. By properly proportioning the number of teeth in the system of gearwheels, the feed-nut is caused to revolve a little faster than the screw-shaft, so that the drill-rod is fed downward a small fraction of an inch for each revolution. To vary the rate of feed, as suitable for different rocks, three pairs of gears with different ratios of teeth are provided. The screw-shaft and gearing are carried by a swivel-head, which can be rotated in a vertical plane, for boring holes at an angle. The hydraulic feed is an improvement on the above, in that the rate of feed is independent of the speed of the rod's rotation and can be adjusted with the utmost nicety. There are either one or two feed cylinders, supplied with water from the pump. The rod, while rotating freely, is supported by the feed cylinder piston and caused to move slowly downward by allowing the water to pass from the lower to the upper part of the cylinder. Wrought iron is a very pure form of commercial iron, having a very small carbon content. ... The old steel cable of a colliery winding tower Steel is a metal alloy whose major component is iron, with carbon being the primary alloying material. ... Hydraulics is a branch of science and engineering concerned with the use of liquids to perform mechanical tasks. ... A spline consists of a long strip of wood (a lath) fixed in position at a number of points. ... A bevel is a slant or angle on a surface. ...

A valve regulates the passage of the water and hence the rate of feed. The bit is of soft steel, set with six to eight or more diamonds, according to its diameter. The diamonds, usually from 12 to 21 carats in size, are carefully set in the bit, projecting but slightly from its surface. Two kinds of diamonds are used, carbons and borts. The carbons are opaque, tougher than the brilliant, and have no cleavage planes. They are therefore suitable for drilling in hard rock. Borts are rough, imperfect brilliants, and are best used for the softer rocks. As the bit wears, the stones must be reset from time to time. The wear of carbons in a well-set bit is small, though extremely variable. Diamond is a Featured Article A scattering of round-brilliant cut diamonds shows off the many reflecting facets. ... Meanings of Carat or Karat: Carat is a unit of mass for gems. ... For the fictional word, see Made_up words in The Simpsons. ... A substance or object that is opaque is neither transparent nor translucent. ... Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite planes, creating smooth surfaces, of which there are several named types: Basal cleavage: cleavage parallel to the base of a crystal, or to the plane of the lateral axes. ...

Above the bit are the core-lifter and core-barrel. The core-lifter is a device for gripping and breaking off the core and raising it to the surface. The barrel, 3 to 10 ft. long, fits closely in the hole and is often spirally grooved for the passage of the water and debris. It serves partly as a guide, tending to keep the hole straight, partly for holding and protecting the core. Diamond drills do not work satisfactorily in broken, fissured rock, as the carbons are liable to be injured, loosened or torn from their settings. In these circumstances, and for soft rocks, the diamond bit may be replaced by a steel-toothed bit. Another apparatus for core drilling is the Davis Calyx drill. For hard rock it has an annular bit, accompanied by a quantity of chilled steel shot; for soft rock, a toothed bit is used. Diamond drill holes are rarely straight, and usually deviate considerably from the direction in which they are started. Very deep holes have been found to vary as much as 45° and even 60° from their true direction. This is due to the fact that the rods do not fit closely in the hole and therefore bend. Fissure (Latin fissura, Plural fissurae) is a groove, natural division, deep furrow, or cleft found in the brain, spinal cord, and liver; or a tear in the anus. ...

It is also likely to occur in drilling through inclined strata, especially when of different degrees of hardness. By using a long and closely fitting core-barrel the liability to deviation is reduced, but cannot be wholly prevented. Holes that are nearly horizontal always deflect upward, because the sag of the rods tilts up tire bit. Diamond drill holes should therefore always be surveyed. This is done by lowering instruments into the hole for observing at a number of successive points the direction and degree of deviation. If accurately surveyed a crooked hole may be quite as useful as a straight one. Surveyor at work with a leveling instrument. ...

References

• This article incorporates text from the 1911 Encyclopædia Britannica, which is in the public domain.