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{{Short description|Tool used to create holes}}
{{About|handheld machines and stationary machines used in a workshop|drilling tunnels|Tunnel boring machine|drilling wells|Drilling rig|other uses}}
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[[File:Drill scheme.svg|thumb|A hand-held corded electric drill]]
[[File:Magnetic Drill.jpg|thumb|A lightweight magnetic-mount drill]]
A '''drill''' is a [[tool]] used for making round holes or driving fasteners. It is fitted with a [[drill bit|bit]], either a [[drill bit|drill]] or [[Screwdriver#Powered screwdriving|driver]] [[Chuck (engineering)#Drill|chuck]]. Hand-operated types are dramatically decreasing in popularity and cordless battery-powered ones proliferating due to increased efficiency and ease of use.
Drills are commonly used in [[woodworking]], [[metalworking]], [[construction]], [[machine tool]] fabrication, construction and utility projects. Specially designed versions are made for miniature applications.
== History ==
[[File:MaryRose-carpentry tools1.jpg|thumb|A wooden drill [[brace (tool)|brace]] and other carpentry tools including a [[mallet]], [[plane (tool)|plane]], [[spokeshave]], and rudimentary [[ruler]]) found on board the 16th century warship ''[[Mary Rose]]'']]
Around 35,000 BC, ''[[Homo sapiens]]'' discovered the benefits of the application of rotary tools. This would have rudimentarily consisted of a pointed rock being spun between the hands to bore a hole through another material.<ref>Roger Bridgeman. 1000 Inventions and Discoveries. The Smithsonian Institution. DK. New York; 2006. p7</ref> This led to the hand drill, a smooth stick, that was sometimes attached to flint point, and was rubbed between the palms. This was used by many ancient civilizations around the world including the [[Maya peoples|Mayans]].<ref>Charles Singer; E. J. Holmyard and A. R. Hall. A History of Technology, Volume 1: From Early Times to Fall of Ancient Empires.  Oxford University Press; London, England.  1967. p. 189</ref> The earliest perforated artifacts, such as [[bone]], [[ivory]], [[Seashells|shells]], and [[antlers]] found, are from the [[Upper Paleolithic]] era.<ref>Charles Singer; E. J. Holmyard and A. R. Hall. A History of Technology, Volume 1: From Early Times to Fall of Ancient Empires. Oxford University Press; London, England.1967. p. 188</ref>[[File:Pistol-grip drill.svg|thumb|Anatomy of a pistol-grip corded drill.]] [[Bow drill]] (strap-drill) are the first machine drills, as they convert a back and forth motion to a rotary motion, and they can be traced back to around 10,000 years ago. It was discovered that tying a cord around a stick, and then attaching the ends of the string to the ends of a stick (a bow), allowed a user to drill quicker and more efficiently. Mainly used to [[Firelighting|create fire]], bow-drills were also used in ancient woodwork, stonework, and dentistry. Archaeologists discovered a [[Neolithic]] grave yard in [[Mehrgarh]], Pakistan, dating from the time of the [[Indus Valley civilisation|Harappans]], around 7,500–9,000 years ago, containing nine adult bodies with a total of eleven teeth that had been drilled.<ref>A, Coppa. "Early Neolithic tradition of [[dentistry]]: [[Flint]] tips were surprisingly effective for dialing tooth enamel in a prehistoric population." Nature. (April 6, 2006.); p755-6</ref> There are [[hieroglyphs]] depicting Egyptian carpenters and bead makers in a tomb at [[Thebes, Egypt|Thebes]] using bow-drills. The earliest evidence of these tools being used in [[Ancient Egypt|Egypt]] dates back to around 2500 BCE.<ref>Charles Singer;E. J. Holmyard and A. R. Hall. A History of Technology, Volume 1: From Early Times to Fall of Ancient Empires.  Oxford University Press; London, England.  1967. p. 190</ref> The usage of bow-drills was widely spread through Europe, Africa, Asia, and North America, during ancient times and is still used today. Over the years many slight variations of bow and strap drills have developed for the various uses of either boring through materials or lighting fires.
The [[core drill]] was developed in ancient Egypt by 3000 BC.<ref name="Delleur" /> The [[pump drill]] was invented during [[Ancient Rome|Roman]] times. It consists of a vertical spindle aligned by a piece of horizontal wood and a [[flywheel]] to maintain accuracy and momentum.<ref>Charles Singer; E. J. Holmyard and A. R. Hall. A History of Technology, Volume 1: From Early Times to Fall of Ancient Empires.  Oxford University Press; London, England.  1967 p. 226</ref>
The hollow-borer tip, first used around the 13th century, consisted of a stick with a tubular shaped piece of metal on the end, such as [[copper]]. This allowed a hole to be drilled while only actually grinding the outer section of it. This completely separates the inner stone or wood from the rest, allowing the drill to pulverize less material to create a similarly sized hole.<ref>Trans. Eileen B. Hennyessy, Ed. Maurice, Daumas.  A History of Technology & Invention: Progress Through the Ages, Volume 1: The Origins of Technological Civilization. Crown Publishers, Inc; New York. 1969</ref>
While the pump-drill and the bow-drill were used in [[Western Culture|Western Civilization]] to bore smaller holes for a larger part of human history, the [[Wood auger|auger]] was used to drill larger holes starting sometime between Roman and Medieval ages.<ref name="history-p502">Trans. Eileen B. Hennyessy, Ed. Maurice, Daumas.  A History of Technology & Invention: Progress Through the Ages, Volume 1: The Origins of Technological Civilization. Crown Publishers, Inc; New York. 1969 p.502</ref> The auger allowed for more torque for larger holes. It is uncertain when the [[Brace (tool)|brace and bit]] was invented; however, the earliest picture found so far dates from the 15th century.<ref name="history-p502" /> It is a type of hand crank drill that consists of two parts as seen in the picture. The brace, on the upper half, is where the user holds and turns it and on the lower part is the bit. The bit is interchangeable as bits wear down. The auger uses a rotating helical screw similar to the Archimedean screw-shaped bit that is common today. The [[Gimlet (tool)|gimlet]] is also worth mentioning as it is a scaled down version of an auger.
Archimedes' screw, present in drills to remove perforation dirt from the hole, was invented in Hellenistic Egypt around 300 BCE.<ref name="Stewart">{{cite book |last=Stewart |first=Bobby Alton |url=https://books.google.com/books?id=5cP-81xDWuwC&pg=PA759 |title=Encyclopedia of water science |author2=Terry A. Howell |publisher=CRC Press |year=2003 |isbn=0-8247-0948-9 |location=USA |page=759}}</ref><ref name="Britannica">{{cite encyclopedia |year=2011 |title=Screw |encyclopedia=Encyclopædia Britannica online |publisher=The Encyclopaedia Britannica Co. |url=https://www.britannica.com/EBchecked/topic/529876/screw |access-date=2011-03-24}}</ref>
The screw pump is the oldest [[Pump#Positive-displacement pumps|positive displacement pump]]. The first records of a water screw, or screw pump, date back to [[Hellenistic Egypt]] before the 3rd century BC.<ref name="Stewart" /> The Egyptian screw, used to lift water from the [[Nile]], was composed of tubes wound round a cylinder; as the entire unit rotates, water is lifted within the spiral tube to the higher elevation. A later screw pump design from Egypt had a spiral groove cut on the outside of a solid wooden cylinder and then the cylinder was covered by boards or sheets of metal closely covering the surfaces between the grooves.<ref name="Stewart" />
In the [[Eastern World|East]], [[churn drills]] were invented as early as 221 BC during the Chinese [[Qin dynasty]],<ref name="geng">{{cite book|author=Geng Ruilun|editor=Guo Huadong|title=New Technology for Geosciences: Proceedings of the 30th International Geological Congress|date=1 October 1997|publisher=VSP|isbn=978-90-6764-265-1|page=225}}</ref> capable of reaching a depth of 1500 m.<ref name="Delleur" /> Churn drills in ancient China were built of wood and labor-intensive, but were able to go through solid rock.<ref name="Landmeyer">{{cite book|author=James E. Landmeyer|title=Introduction to Phytoremediation of Contaminated Groundwater: Historical Foundation, Hydrologic Control, and Contaminant Remediation|date=15 September 2011|publisher=Springer|isbn=978-94-007-1956-9|page=112}}</ref> The churn drill appears in Europe during the 12th century.<ref name="Delleur">{{cite book|author=Jacques W. Delleur|title=The Handbook of Groundwater Engineering, Second Edition|date=12 December 2010|publisher=Taylor & Francis|isbn=978-0-8493-4316-2|page=7 in chapter 2}}</ref> In 1835 Isaac Singer is reported to have built a steam powered churn drill based on the method the Chinese of a rod tipped with a bit.<ref>Alban J. Lynch; Chester A. Rowland (2005). The History of Grinding. p.173</ref> Also worth briefly discussing are the early [[#Drill press|drill presses]]; they were machine tools that derived from bow-drills but were powered by [[windmill]]s or [[Watermill|water wheel]]s. Drill presses consisted of the powered drills that could be raised or lowered into a material, allowing for less force by the user.
In 1813 [[Richard Trevithick]] designed a steam-driven rotary drill, also the first drill to be powered by steam.<ref>{{cite book|url=https://books.google.com/books?id=35Y7AwAAQBAJ&q=Trevithick+Rotary+Drill&pg=PT114|title=History's Most Dangerous Jobs Miners|first=Anthony|last=Burton|date=1 February 2013|publisher=History Press|access-date=8 May 2018|via=Google Books|url-status=live|archive-url=https://web.archive.org/web/20170627023422/https://books.google.co.uk/books?id=35Y7AwAAQBAJ&pg=PT114&dq=Trevithick+Rotary+Drill&hl=en&sa=X&ved=0ahUKEwiEoPOzj5HKAhUBlxQKHbpkAiwQ6AEIUzAI#v=onepage&q=Trevithick+Rotary+Drill&f=false|archive-date=27 June 2017|isbn=9780752492254}}</ref> In 1848 J.J. Couch invented the first pneumatic percussion drill.<ref>{{Cite book |last=Lynch |first=Alban J. |title=The history of grinding |last2=Rowland |first2=Chester A. |date=2005 |publisher=Soc. for Mining, Metallurgy, and Exploration, Inc |isbn=978-0-87335-238-3 |location=Littleton, Colo |pages=174}}</ref><ref>{{Cite web |date=2018-07-26 |title=The First Percussion Drill |url=https://www.constructionequipment.com/topical/historical-equipment/article/10755034/the-first-percussion-drill |access-date=2024-08-30 |website=Construction Equipment |language=en}}</ref><ref>{{Cite web |date=2024-07-28 |title=Drilling machinery {{!}} Types, Uses & Benefits {{!}} Britannica |url=https://www.britannica.com/technology/drilling-machinery#ref93871 |access-date=2024-08-30 |website=www.britannica.com |language=en}}</ref>
The next great advancement in drilling technology, the [[electric motor]], led to the invention of the electric drill. It is credited to mining engineers [[Arthur James Arnot]] and [[William Blanch Brain]] of [[Melbourne]], Australia who patented the electric drill in 1889.<ref>"Specifications for registration of patent by William Blanch Brain and Arthur James Arnot titled – Improvements in electrical rock drills coal diggers and earth cutters" National Archives of Australia.1889 Retrieved 1 April 2006</ref>
The first portable handheld drill was created by in 1895 by brothers [[Wilhelm Emil Fein|Wilhelm & Carl Fein]] of [[Stuttgart]], Germany. In 1917 the first trigger-switch, pistol-grip portable drill was patented by [[Black & Decker]].<ref>US patent 1,245,860, S.D. Black & A.G. Decker, "Electrically driven tool", issued 1917-11-06</ref> This was the start of the modern drill era. Over the last century the electric drill has been created in a variety of types and multiple sizes for an assortment of specific uses.
==Types==
There are many types of drills: some are powered manually, others use electricity (electric drill) or compressed air (''pneumatic drill'') as the motive power, and a minority are driven by an [[internal combustion engine]] (for example, earth drilling augers). Drills with a percussive action ([[hammer drill]]s) are mostly used in hard materials such as [[masonry]] (brick, concrete and stone) or [[rock (geology)|rock]]. [[Drilling rig]]s are used to bore holes in the earth to obtain water or oil. Oil wells, [[water well]]s, or holes for [[geothermal heating]] are created with large drilling rigs. Some types of hand-held drills are also used to drive [[screw]]s and other [[fastener]]s. Some small appliances that have no motor of their own may be drill-powered, such as small pumps, grinders, etc.
===Primitive===
Some forms of drills have been used since Pre-History, both to make holes in hard objects or as [[Fire drill (tool)|fire drills]].
* [[Bone tool#Awls|Awl]] – The shaft is twisted with one hand
* [[Hand drill]] – The shaft is spun by rubbing motion of the hands
* [[Bow drill]] – The shaft is spun by cord of a bow that is moved back and forth.
* [[Pump drill]] – The shaft is spun by pushing down on a hand bar and by a flywheel
=== {{anchor|Hand drill}} Hand-powered ===
Hand-powered metal drills have been in use for centuries. They include:
* [[Wood auger|Auger]], a straight shaft with a wood-cutting blade at the bottom and a T-shaped handle
* [[Brace and bit|Brace]], a modified auger powered by means of a [[crankshaft]]
* [[Gimlet (tool)|Gimlet]], a small tool for drilling holes
* [[Bradawl]], similar to a [[screwdriver]] but with a drilling point
* [[Cranial drill]], an instrument used throughout skull surgery
* {{Vanchor|Wheel brace}} or hand drill, also known as an {{Vanchor|eggbeater drill}}, as it is analogous in form to a hand-cranked [[Eggbeater (mixer)|eggbeater]] with [[bevel gear]]s
** Breast drill, a heavy duty subtype of eggbeater drill that has a flat chest piece in addition to one or more handles
* [[Push drill|Push]], such as [[Yankee screwdriver|Yankee]] or Persian drills, which use spiral or [[ratchet (device)|ratcheting]] mechanisms
* [[Pin chuck]], a small hand-held jeweler's drill
<gallery>
File:La_Tour.jpg|Painting by [[Georges de La Tour]] of [[Saint Joseph|St. Joseph]] operating an auger
File:PalmercarpenterA.jpg|Carpenter using a hand-powered [[brace (tool)|brace]] to drill a hole
File:drill004cropped.jpg|A traditional wheel brace or hand drill, with hollow wooden handle and screw-on cap used for storing bits
</gallery>
===Power drills===
Drills powered by electricity (or more rarely, compressed air) are the most common tools in woodworking and machining shops.
[[Image:CordlessDrill.jpg|thumb|Cordless drill]]
Electric drills can be [[Electrical cable|corded]] (fed from an [[electric outlet]] through a [[power cable]]) or [[cordless]] (fed by [[rechargeable battery|rechargeable electric batteries]]). The latter have removable battery packs that can be swapped to allow uninterrupted drilling while recharging.
A popular use of hand-held power drills is to set screws into wood, through the use of [[screwdriver bit]]s. Drills optimized for this purpose have a [[clutch]] to avoid damaging the slots on the screw head.
* [[Pistol-grip drill]] – the most common hand-held power drill type.
* [[Right-angle drill]] – used to drill or drive screws in tight spaces.
* [[Hammer drill]] – combines rotary motion with a hammer action for drilling [[masonry]]. The hammer action may be engaged or disengaged as required.
* [[Drill press]] – larger power drill with a rigid holding frame, standalone mounted on a bench
[[Image:Bosch GBH5-40 LargeDrill.jpg|thumb|right|A heavy duty rotary hammer drill]]
* [[Rotary hammer]] combines a primary dedicated hammer mechanism with a separate rotation mechanism, and is used for more substantial material such as masonry or concrete.
Most electric hammer drills are rated (input power) at between 600 and 1100 watts. The efficiency is usually 50–60% i.e. 1000 watts of input is converted into 500–600 watts of output (rotation of the drill and hammering action).
For much of the 20th century, attachments could commonly be purchased to convert corded electric hand drills into a range of other power tools, such as orbital sanders and power saws, more cheaply than purchasing dedicated versions of those tools. As the prices of power tools and suitable electric motors have fallen such attachments have become much less common.
Early cordless drills used interchangeable 7.2&nbsp;[[volt|V]] battery packs. Over the years battery voltages have increased, with 18&nbsp;V drills being most common, but higher voltages are available, such as 24&nbsp;V, 28&nbsp;V, and 36&nbsp;V. This allows these tools to produce as much [[torque]] as some corded drills.
Common battery types of are [[Nickel-cadmium battery|nickel-cadmium (NiCd) batteries]] and [[lithium ion battery|lithium-ion batteries]], with each holding about half the [[market share]]. NiCd batteries have been around longer, so they are less expensive (their main advantage), but have more disadvantages compared to lithium-ion batteries. NiCd disadvantages are limited life, self-discharging, environment problems upon disposal, and eventually internally [[short circuit]]ing due to [[Dendrite (metal)|dendrite]] growth. Lithium-ion batteries are becoming more common because of their short charging time, longer life, absence of [[memory effect]], and low weight. Instead of charging a tool for an hour to get 20 minutes of use, 20 minutes of charge can run the tool for an hour in average. Lithium-ion batteries also hold a charge for a significantly longer time than nickel-cadmium batteries, about two years if not used, vs. 1 to 4 months for a nickel-cadmium battery.
====Impact drills====
{{main|Impact wrench}}
Also known as impact wrenches, is a form of drill that incorporates a hammer motion along with the rotating motion of a conventional drill. The hammering aspect of the impact drill occurs when the power of the motor cannot turn the bolt it will begin exerting bursts of force to "hammer" the bolt in the desired direction. These drills are commonly used to secure long bolts or screws into wood, metal, and concrete, as well as loosening ceased or over torqued bolts. Impact drills come in two major types, pneumatic and electric, and vary in size depending on application. Electric impact drills are most often found cordless and are widely used in construction, automobile repair, and fabrication. These electric drills are preferred over the pneumatic driven because of their maneuverability and ease of use. Pneumatic impact drills rely on air and have to remain connected to an air source to maintain power. The chuck on impact drills is different from the conventional handheld power drill. The chuck acts more as a collet with a hexagonal shape in which the bits and drivers lock into. Impact drivers can also be used to bore holes like a standard pistol grip drill, but this requires a special bit that will lock into the hexagonal collet. The design of the impact drills are almost identical to modern pistol grip power drills with only one major difference. Impact drills have a shorter, skinnier, stubby receiver where the collet is located compared to the larger tapered chuck on a conventional drill. This allows the user to fit in smaller places that a normal drill would not. Impact drills are not great in regards to torque and speed control. Most handheld drills have a variable speed option, whereas most impact drills have a fixed torque and speed. Impact drills are not designed for precision work due to this lack of adjustability.<ref>{{Cite web|date=2020-07-22|title=Solved! What Is an Impact Driver?|url=https://www.bobvila.com/articles/what-is-an-impact-driver/|access-date=2021-09-23|website=Bob Vila|language=en|archive-date=2021-10-25|archive-url=https://web.archive.org/web/20211025002505/https://www.bobvila.com/articles/what-is-an-impact-driver/|url-status=live}}</ref>
====Hammer drill====
{{main|Hammer drill}}
<!--This should be moved to [[hammer drill]]>-->
The hammer action of a hammer drill is provided by two cam plates that make the chuck rapidly pulse forward and backward as the drill spins on its axis. This pulsing (hammering) action is measured in Blows Per Minute (BPM) with 10,000 or more BPMs being common. Because the combined mass of the chuck and bit is comparable to that of the body of the drill, the energy transfer is inefficient and can sometimes make it difficult for larger bits to penetrate harder materials such as poured concrete. A standard hammer drill accepts 6&nbsp;mm (1/4&nbsp;inch) and 13&nbsp;mm (1/2&nbsp;inch) drill bits. The operator experiences considerable vibration, and the cams are generally made from hardened steel to avoid them wearing out quickly. In practice, drills are restricted to standard masonry bits up to 13&nbsp;mm (1/2&nbsp;inch) in diameter. A typical application for a hammer drill is installing electrical boxes, conduit straps or shelves in concrete.
====Rotary hammer====
{{main|Rotary hammer}}
<!--This should be moved to [[rotary hammer]] -->
The rotary hammer (also known as a rotary hammer drill, roto hammer drill or masonry drill). Standard chucks and parallel-shank carbide-tipped drills have been largely superseded by [[Chuck (engineering)#Special Direct System (SDS)|SDS]] chucks and matching (spline shank) drills, that have been designed to better withstand and transmit the percussive forces. These bits are effective at pulverising the masonry and drill into this hard material. Some styles of this tool are intended for masonry drilling only and the hammer action cannot be disengaged. Other styles allow the drill to be used without the hammer action for normal drilling, or hammering to be used without rotation for chiselling.
In contrast to the cam-type hammer drill, a rotary/pneumatic hammer drill accelerates only the bit. This is accomplished through a piston design, rather than a spinning cam. Rotary hammers have much less vibration and penetrate most building materials. They can also be used as "drill only" or as "hammer only" which extends their usefulness for tasks such as chipping brick or concrete. Hole drilling progress is greatly superior to cam-type hammer drills, and these drills are generally used for holes of 19&nbsp;mm (3/4&nbsp;inch) or greater in size. A typical application for a rotary hammer drill is boring large holes for lag bolts in foundations, or installing large lead anchors in concrete for handrails or benches.
====Drill press====
{{main|Drill press}}
[[Image:Drillpress.jpg|thumb|right|A drill press]]
[[File:Woman operating boring machine; boring wooden reels for winding barbed wire.jpg|thumb|upright|Drill press (then called a boring machine) boring wooden reels for winding barbed wire, 1917]]
<!-- This section whould be moved to [[drill press]] -->
A drill press (also known as a pedestal drill, pillar drill, or bench drill) is a style of drill that may be mounted on a stand or bolted to the floor or [[workbench]]. Portable models are made, some including a magnetic base. Major components include a base, column (or pillar), adjustable table, spindle, chuck, and drill head, usually driven by an electric motor. The head typically has a set of three handles radiating from a central hub that are turned to move the spindle and chuck vertically. The distance from the center of the chuck to the closest edge of the column is the throat. The swing is simply twice the throat, and the swing is how drill presses are classified and sold. Thus, a tool with 4" throat has an 8" swing (it can drill a hole in the center of an 8" work piece), and is called an 8" drill press.<ref>{{Cite news|last=Chad|date=2011-10-12|title=Choosing a Drill Press|url=https://extremehowto.com/its-a-drill-press-check-out-some-modern-features-and-diy-jigs/|access-date=2021-06-28|website=Extreme How To|archive-date=2021-06-28|archive-url=https://web.archive.org/web/20210628143209/https://extremehowto.com/its-a-drill-press-check-out-some-modern-features-and-diy-jigs/|url-status=live}}</ref>
A drill press has a number of advantages over a hand-held drill:
* Less effort is required to apply the drill to the workpiece. The movement of the chuck and spindle is by a lever working on a [[rack and pinion]], which gives the operator considerable [[mechanical advantage]]
* The table allows a [[vise (tool)|vise]] or [[Clamp (tool)|clamp]] to be used to position and restrain the work, making the operation much more secure
* The angle of the spindle is fixed relative to the table, allowing holes to be drilled accurately and consistently
* Drill presses are almost always equipped with more powerful motors compared to hand-held drills. This enables larger drill bits to be used and also speeds up drilling with smaller bits.
For most drill presses—especially those meant for woodworking or home use—speed change is achieved by manually moving a belt across a stepped [[pulley]] arrangement. Some drill presses add a third stepped pulley to increase the number of available speeds. Modern drill presses can, however, use a variable-speed motor in conjunction with the stepped-pulley system. Medium-duty drill presses such as those used in machine shop (tool room) applications are equipped with a [[continuously variable transmission]]. This mechanism is based on variable-diameter pulleys driving a wide, heavy-duty belt. This gives a wide speed range as well as the ability to change speed while the machine is running. Heavy-duty drill presses used for metalworking are usually of the gear-head type described below.
Drill presses are often used for miscellaneous workshop tasks other than drilling holes. This includes sanding, honing, and polishing. These tasks can be performed by mounting sanding drums, honing wheels and various other rotating accessories in the chuck. This can be unsafe in some cases, as the chuck arbor, which may be retained in the spindle solely by the friction of a [[Morse taper|taper fit]], may dislodge during operation if the side loads are too high.
====Geared head====
[[Image:geared drill press.jpg|thumb|A geared head drill press, with up to eight possible speeds accessible via shift levers on the head and a two speed motor control immediately in front of the quill handle]]
A geared head drill press transmits power from the motor to the spindle through [[gear|spur gearing]] inside the machine's head, eliminating a flexible drive belt. This assures a positive drive at all times and minimizes maintenance. Gear head drills are intended for metalworking applications where the drilling forces are higher and the desired speed (RPM) is lower than that used for woodworking.
Levers attached to one side of the head are used to select different gear ratios to change the spindle speed, usually in conjunction with a two- or three-speed motor (this varies with the material). Most machines of this type are designed to be operated on [[three-phase electric power]] and are generally of more rugged construction than equivalently sized belt-driven units. Virtually all examples have geared racks for adjusting the table and head position on the column.
Geared head drill presses are commonly found in [[tool room]]s and other commercial environments where a heavy duty machine capable of production drilling and quick setup changes is required. In most cases, the spindle is machined to accept Morse taper tooling for greater flexibility. Larger geared head drill presses are frequently fitted with power feed on the quill mechanism, with an arrangement to disengage the feed when a certain drill depth has been achieved or in the event of excessive travel. Some gear-head drill presses have the ability to perform [[tap and die|tapping]] operations without the need for an external tapping attachment. This feature is commonplace on larger gear head drill presses. A clutch mechanism drives the tap into the part under power and then backs it out of the threaded hole once the proper depth is reached. Coolant systems are also common on these machines to prolong tool life under production conditions.
====Radial arm====
[[Image:radp01.jpg|thumb|Radial arm drill press]]A radial arm drill press is a large geared-head drill press in which the head can be moved along an arm that [[Vector (geometric)|radiates]] from the machine's column. As it is possible to swing the arm relative to the machine's base, a radial arm drill press is able to operate over a large area without having to reposition the workpiece. This feature saves considerable time because it is much faster to reposition the machine's head than it is to unclamp, move, and then re-clamp the workpiece to the table. The size of work that can be handled may be considerable, as the arm can swing out of the way of the table, allowing an [[overhead crane]] or [[derrick]] to place a bulky workpiece on the table or base. A vise may be used with a radial arm drill press, but more often the workpiece is secured directly to the table or base, or is held in a [[Fixture (tool)|fixture]].
Power spindle feed is nearly universal with these machines and coolant systems are common. Larger-size machines often have power feed motors for elevating or moving the arm. The biggest radial arm drill presses are able to drill holes as large as four inches or 100{{nbsp}}mm diameter in solid steel or cast iron. Radial arm drill presses are specified by the diameter of the column and the length of the arm. The length of the arm is usually the same as the maximum throat distance. The radial arm drill press pictured to the right has a 9-inch diameter and a 3-foot-long arm. The maximum throat distance of this machine would be approximately 36 inches, giving a maximum swing of 72 inches (6 feet or 1.8{{nbsp}}m).
====Magnetic drill press====
{{Main|Magnetic drilling machine}}
A '''magnetic drill''' is a portable machine for drilling holes in large and heavy workpieces which are difficult to move or bring to a stationary conventional drilling machine. It has a magnetic base and drills holes with the help of cutting tools like [[annular cutter]]s (broach cutters) or with [[Drill bit|twist drill bits]]. There are various types depending on their operations and specializations, like magnetic drilling / tapping machines, cordless, pneumatic, compact horizontal, automatic feed, cross table base etc.
====Mill====
Mill drills are a lighter alternative to a [[milling machine]]. They combine a drill press (belt driven) with the X/Y coordinate abilities of the milling machine's table and a locking collet that ensures that the cutting tool will not fall from the spindle when lateral forces are experienced against the bit. Although they are light in construction, they have the advantages of being space-saving and versatile as well as inexpensive, being suitable for light machining that may otherwise not be affordable.
==Surgical==
Drills are used in [[surgery]] to remove or create holes in [[bone]]; specialties that use them include [[dentistry]], [[orthopedic surgery]] and [[neurosurgery]]. The development of surgical drill technology has followed that of industrial drilling, including transitions to the use of lasers, [[endoscopy]], use of advanced imaging technologies to guide drilling, and robotic drills.<ref>{{cite book |last1=Durand |first1=R. |last2=Voyer |first2=R. |editor1-last=Emami |editor1-first=E. |editor2-last=Feine J. |editor2-first=J. |title=Mandibular implant prostheses |date=2018 |publisher=Springer |isbn=978-3-319-71181-2 |pages=107–153 |chapter=Step-by-Step Surgical Considerations and Techniques.|doi=10.1007/978-3-319-71181-2_8}}</ref><ref>{{cite journal |last1=Rajitha Gunaratne |first1=GD |last2=Khan |first2=R |last3=Fick |first3=D |last4=Robertson |first4=B |last5=Dahotre |first5=N |last6=Ironside |first6=C |title=A review of the physiological and histological effects of laser osteotomy. |journal=Journal of Medical Engineering & Technology |date=January 2017 |volume=41 |issue=1 |pages=1–12 |doi=10.1080/03091902.2016.1199743 |pmid=27345105|s2cid=22296217 }}</ref><ref>{{cite journal |last1=Coulson |first1=CJ |last2=Reid |first2=AP |last3=Proops |first3=DW |last4=Brett |first4=PN |title=ENT challenges at the small scale. |journal=The International Journal of Medical Robotics and Computer Assisted Surgery |date=June 2007 |volume=3 |issue=2 |pages=91–6 |doi=10.1002/rcs.132 |pmid=17619240|s2cid=23907940 }}</ref><ref>{{cite news |last1=Darzi |first1=Ara |title=The cheap innovations the NHS could take from sub-Saharan Africa |url=https://www.theguardian.com/healthcare-network/2017/oct/27/cheap-innovations-nhs-take-sub-saharan-africa |work=The Guardian |date=27 October 2017 |language=en |access-date=2 December 2018 |archive-date=2 December 2018 |archive-url=https://web.archive.org/web/20181202155101/https://www.theguardian.com/healthcare-network/2017/oct/27/cheap-innovations-nhs-take-sub-saharan-africa |url-status=live }}</ref>
==Accessories==
Drills are often used simply as motors to drive a variety of applications, in much the same way that tractors with generic [[Power take-off|PTO]]s are used to power ploughs, mowers, trailers, etc.
Accessories available for drills include:
* [[Screwdriver|Screw-driving]] tips of various kinds – flathead, Philips, etc. for driving screws in or out
* Water pumps
* Nibblers for cutting metal sheet
* Rotary sanding discs
* Rotary polishing discs
* Rotary cleaning brushes
== Drill bits ==
{{main|Drill bit}}
Some of the main drill bit types are
* [[Twist drill|twist drill bits]] – a general purpose drill bit for making holes in wood, plastic, metals, concrete and more
* Counterbore Drill Bits – a drill bit used to enlarge existing holes
* [[Countersink|Countersink Drill Bits]] – a drill bit to create a wide opening for a screw
* High-Speed Drill Bits – these are drill bits made to be very strong and therefore are often used to cut metals
* Spade drill Bits – spade-shaped drill bits used primarily to bore holes in softwoods
* Hole Saw – a large drill bit with a jagged edge, ideal for cutting larger holes (mostly in wood).
==Capacity==
Drilling capacity indicates the maximum [[diameter]] a given [[power drill]] or [[drill press]] can produce in a certain material. It is essentially a proxy for the continuous [[torque]] the machine is capable of producing. Typically a given drill will have its capacity specified for different materials, i.e., 10&nbsp;mm for steel, 25&nbsp;mm for wood, etc.
For example, the maximum recommended capacities for the [[DeWalt]] DCD790 cordless drill for specific [[drill bit]] types and materials are as follows:<ref>{{cite web|title=DeWalt DCD790/DCD795 Instruction Manual|url=http://servicenet.dewalt.com/Products/GetDocument?docName=N213852,DCD790.pdf&productId=120665&productType=undefined&documentId=44200&translatedFileName=http://documents.dewalt.com/documents/English/Instruction%20Manual/N213852,DCD790.pdf|publisher=[[DeWalt]]|access-date=22 May 2014|page=14|archive-date=22 May 2014|archive-url=https://web.archive.org/web/20140522234427/http://servicenet.dewalt.com/Products/GetDocument?docName=N213852,DCD790.pdf&productId=120665&productType=undefined&documentId=44200&translatedFileName=http://documents.dewalt.com/documents/English/Instruction%20Manual/N213852,DCD790.pdf|url-status=live}}</ref>
{| class="wikitable"
|-
! Material !! Drill bit type !! Capacity
|-
| rowspan="5" | Wood
| [[Drill bit#Auger bit|Auger]] || {{Convert|7/8|in|mm|0|abbr=on}}
|-
| [[Drill bit#Wood spade bit|Paddle]] || {{Convert|1+1/4|in|mm|0|abbr=on}}
|-
| [[Drill bit#Twist drill bit|Twist]] || {{Convert|1/2|in|mm|0|abbr=on}}
|-
| [[Drill bit#Forstner bit|Self-feed]] || {{Convert|1+3/8|in|mm|0|abbr=on}}
|-
| [[Hole saw]] || {{Convert|2|in|mm|0|abbr=on}}
|-
| rowspan="2" | Metal
| Twist || {{Convert|1/2|in|mm|0|abbr=on}}
|-
| Hole saw || {{Convert|1+3/8|in|mm|0|abbr=on}}
|}
==See also==
* [[Boring (manufacturing)|Boring]]
* [[Dental drill]]
* [[Drifter drill]]
* [[Drill bit]]
* [[Drill bit sizes]]
== References ==
{{Reflist}}
== External links ==
{{commons}}
* [http://www.bls.gov/opub/cwc/sh20040624ar01p1.htm Nonfatal Occupational Injuries Involving the Eyes] – From US Department of Labor (Accessed 29 April 2007)
* [http://wwwn.cdc.gov/niosh-sound-vibration/  NIOSH Power Tools Sound and Vibrations Database] {{Webarchive|url=https://web.archive.org/web/20160630135841/http://wwwn.cdc.gov/niosh-sound-vibration/ |date=2016-06-30 }}
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{{Power tools}}
{{Woodworking}}
{{Authority control}}
[[Category:Hole making]]
[[Category:Rotating machines]]
[[Category:Tools]]
[[Category:Construction]]