1. What is a Screw? What is a Screwdriver?

A screw is a shaft with a helical groove or thread formed on its surface. Its main uses are as a threaded fastener used to hold objects together, and as a simple machine used to translate torque into linear force. It can also be defined as an inclined plane wrapped around a shaft.

A screw is any shaft with a corkscrew-shaped groove formed on its surface. Screws are used to fasten two objects together. A screwdriver is a tool for driving (turning) screws; screwdrivers have a tip that fits into the head of a screw

History

2. In antiquity, the Greek mathematician Archytas of Tarentum (428 – 350 BC) was credited with the invention of the screw. Pythagorean philosopher, mathematician and astronomer, Archytas is sometimes called the father of mathematical mechanics.
He is thought to be the inventor of the screw and the pulley, and a forefather of mechanical flight. He was a friend of Plato and a teacher of Eudoxus of Cnidus.
In 425 BC he constructed the first flying machine in history. His "pigeon" (as he called it) was powered by a system of jet propulsion, and in one experiment it flew a distance of 200 metres. Once it fell to the ground, however, this machine could not take off again. Evanghelos Stamatis thinks it must have been some sort of jet-propelled craft driven by a compressed air system.
This, then, was an early application of aerodynamics, that is, the harnessing of the force of compressed air; and it is not a legend: Archytas' experiment is attested in literature and is a matter of fact. The inventor of the "pigeon" was an exceptional mathematician and engineer, an avid builder of mechanical constructions, and is held to be the inventor of the screw, the pulley and a child's rattle.

3. Archimedes (c. 287 BC–212 BC)

Was an ancient Greek mathematician, physicist, engineer, astronomer and philosopher born in the seaport colony of Syracuse, Sicily and his name was for first time associated with screw. He is considered by some historians of mathematics to be one of the greatest mathematicians in antiquity

Archimedes became a popular figure as a result of his involvement in the defense of Syracuse against the Roman siege in the Second Punic War. He is reputed to have discovered the principles of density and buoyancy, also known as Archimedes' principle, while taking a bath (thereupon taking to the streets naked he called "Eureka"). He has also been credited with the possible invention of the odometer during the First Punic War. One of his inventions used for military defense of Syracuse against the invading Romans was the claw of Archimedes.

A diagram showing how Archimedes may have enabled the defenders of Syracuse aim their mirrors at approaching ships

It is said that he prevented one Roman attack on Syracuse by using a large array of mirrors (speculated to have been highly polished shields) to reflect sunlight onto the attacking ships causing them to catch fire.
It is also said that Archimedes invented the catapult to hurl boulders at attacking ships. While at first seeming plausible because he did invent several types of pulley systems, the catapult is recorded as actually having been used by Dionysius 1 of Syracuse approximately one hundred years earlier.

Archimedes was killed by a Roman soldier in the sack of Syracuse during the Second Punic War, despite orders from the Roman general, Marcellus, that he was not to be harmed. The Greeks said that he was killed while drawing an equation in the sand; engrossed in his diagram and impatient with being interrupted, he is said to have muttered his famous last words before being slain by an enraged Roman soldier: "Don't disturb my circles". This story was sometimes told to contrast the Greek high-mindedness with Roman ham-handedness; however, it should be noted that Archimedes designed the siege engines that devastated a substantial Roman invasion force, so his death may have been out of retribution.

4. Archimedes' screw, or the Archimedean screw, is a machine historically used for transferring water from a low-lying body of water into irrigation ditches. It is one of several inventions and discoveries reputed to have been made by Archimedes, though writings about the Hanging Gardens of Babylon hint that a similar device was used by the Mesopotamians as early as 600 BC – over 300 years before his birth.

The machine consists of a screw inside a hollow pipe. A screw can be thought of as an inclined plane (another simple machine) wrapped around a cylinder.

The lower end of the device is put in the water, and the screw is then turned (usually by a windmill or by manual labor). As the bottom end of the tube turns, it scoops up a volume of water. This amount of water will slide up in the spiral tube as the shaft is turned, until it finally pours out from the top of the tube and feeds the irrigation systems.

The interface between the screw and the pipe does not need to be perfectly water-tight because of the relatively large amount of water being scooped at each turn in respect to the angular speed of the screw. Also, water leaking from the top section of the screw leaks into the previous one and so on, so a sort of equilibrium is achieved while using the machine, thus preventing a decrease in efficiency.

The "screw" does not necessarily need to turn inside the casing, but can be allowed to turn with it in one piece. A screw could be sealed with pitch or some other adhesive to its casing, or, cast as a single piece in bronze, as some researchers have postulated as being the devices used to irrigate Sennacherib's Hanging Gardens of Babylon. Depictions of Greek and Roman water screws show the screws being powered by a human treading on the outer casing to turn the entire apparatus as one piece, which would require that the casing be rigidly attached to the screw.

The design of the everyday Greek and Roman water screw, in contrast to the heavy bronze device of Sennacherib, with its problematic drive chains, has a powerful simplicity. A double or triple helix was built of wood strips (or occasionally bronze sheeting) around a heavy wooden pole. A cylinder was built around the helices using long, narrow boards fastened to their periphery and waterproofed with pitch
Archimedes screw was still used over 2000 years without essentially changes, for various types of applications.

Ericson's Propeller

The idea of using a modified screw to propel a ship had been proposed as early as 1752. John Fitch experimented with a screw propeller before his steam paddle boat. Both the Bushnell (1777) and Fulton (1797) submarines used propellers. Of course a paddlewheel would not make sense for an underwater boat, so propellers were mandatory on submarines.

Several experiments were made with different versions of a screw propeller. These assumed that a ship could be propelled not by sail, oars, or paddlewheels, but by a modified version of the Archimedes screw. One preferred design included a long tube enclosing a screw shape, like the historical water lifting device called the Archimedes Screw. Some did away with the tube, and just had a long screw. In 1834 Britain Francis Pettit Smith built one such long wooden screw to drive his 237 ton ship Archimedes. In trials part of the long screw broke off, and to everyone's surprise, instead of slowing the ship down, the shorter screw speeded it up. More experiments arrived at a very short screw shape, closer to what we know as a propeller. Steven's also successfully used propellers on his 1804 double prop steam boat.

At the same time in the U.S., Swedish born John Ericsson built a similar screw. His 1838 U.S. patent figures are shown below. His screw was a double propeller, and the two props were counter rotating. His screw pattern was explained in the patent as being based on spiral screws around a cylinder, like an Archimedes screw, but only a section of the cylinder was used

Smith's Archimedes, Propeller Driven Ship

The idea of using a modified screw to propel a ship had been proposed as early as 1752. John Fitch experimented with a screw propeller before his steam paddle boat. Both the Bushnell (1777) and Fulton (1797) submarines used propellers. Of course a paddlewheel would not make sense for an underwater boat, so propellers were mandatory on submarines.

Several experiments were made with different versions of a screw propeller. These assumed that a ship could be propelled not by sail, oars, or paddlewheels, but by a modified version of the Archimedes screw. One preferred design included a long tube enclosing a screw shape, like the historical water lifting device called the Archimedes Screw. Some did away with the tube, and just had a long screw. In 1834 Britain Francis Pettit Smith built one such long wooden screw to drive his 237 ton ship Archimedes. In trials part of the long screw broke off, and to everyone's surprise, instead of slowing the ship down, the shorter screw speeded it up. More experiments arrived at a very short screw shape, closer to what we know as a propeller.

The original propeller of the Archimedes was mounted about in the center of the hull, and was really a screw, not a bladed propeller that later was developed. First tested in 1839, the Archimedes hoped to achieve 4-5 knots, but the engineering world was astounded when it achieved 9.5 knots. However, the engineering world was skeptical, and many were adamently opposed not only to screw propellers, but also iron ships and steam power. The Rattler was built for the British Navy in 1841.

One of eight 12-ft.-diameter Archimedes screws used to handle rainstorm runoff in Texas City, Texas, USA. Each screw is driven by a 750-hp diesel engine and can pump up to 125,000 gallons per minute. Manufactured by Enviro Development Co. of Mountain View, California, USA. Picture scanned from Popular Mechanics (April 1980, page 62).

An Egyptian farmer turning an Archimedes screw by hand to irrigate a field.

Seven Archimedes screws pump wastewater in a treatment plant in Memphis, Tennessee, USA. Each of these screws is 96 inches (2.44 meters) in diameter and can lift 19,900 gallons per minute.

Three large Archimedes screws lift treated wastewater to aeration basins at the Fred Hervey Water Reclamation Plant of El Paso, Texas, USA. Built in 1985, the 10-million gallon/day plant treats wastewater to be injected into the Hueco Bolson Aquifer serving El Paso and Ciudad Juarez, Mexico.

Two Archimedes screws in SeaWorld Adventure Park (San Diego, California, USA) used to lift water for the Shipwreck Rapids water ride.

An Archimedes screw the diameter of a pencil eraser is used in this Hemopump cardiac assist system. This system maintains blood circulation during acute heart failure, minimally invasive coronary bypass surgery, and other surgical procedures.

5. By the 1st century BC, wooden screws were commonly used throughout the Mediterranean world in devices such as oil and wine presses, and for pressing clothes.

6. Metal screws used as fasteners did not appear in Europe until the 1400s.
Mass Production of Screws
In 1770, English instrument maker, Jesse Ramsden (1735-1800) invented the first satisfactory screw-cutting lathe. Ramsden inspired other inventors.

In 1797, Englishmen, Henry Maudslay (1771-1831) invented a large screw-cutting lathe that made it possible to mass-produce accurately sized screws. In 1798, American David Wilkinson also invented machinery for the mass production of threaded metal screws.

Robertson Screw
In 1908, P. L. Robertson began to manufacture a square recess impression in the head of a screw in Milton, Ontario, Canada. At that time, it was a revolutionary change in the fastener industry. The first patent was issued in 1909 and the last patent expired 55 years later in 1964. For his invention, P.L. Robertson screws and screwdrivers carry his name to this day.

In 1908, square-drive screws were invented by Canadian P. L. Robertson. Twenty-eight years before Henry Phillips patented his Phillips head screws, which are also square-drive screws.The Robertson screw is considered the "first recess-drive type fastener practical for production usage." The design became a North American standard, as published in the sixth edition of Industrial Fasteners Institute Metric and Inch Standards. A square-drive head on a screw can be better than a slot head because the screwdriver will not slip out of the screw's head during installation. The Model T car made by the Ford Motor Company (one of Robertson's first customers) used over seven hundred Robertson screws.
Phillips Head Screw
In the early 1930s, the Phillips head screw was invented by Henry Phillips. Automobile manufacturers now used car assembly lines. They needed screws that could take greater torque and could provide tighter fastenings. The Phillips head screw was compatible with the automated screwdrivers used in assembly line.

Ironically, there is a Philips Screw Company that never made Phillips screws or drivers. Henry Phillips died in 1958 at the age of sixty-eight.

Allen Key

A hexagonal or hex screw head has a hexagonal hole turned by a Allen key. An Allen key is a hexagonal shaped wrench. The Allen key may have been invented by American, Gilbert F. Heublein, however, this is still being researched and should not be considered a fact. Heublein was an importer and distributor of foods and beverage. who in 1892 introduced "The Club Cocktails", the world's first bottled cocktails.
Screwdriver
In 1744, the flat-bladed bit for the carpenter's brace was invented, the precursor to the first simple screwdriver. Handheld screwdrivers first appeared after 1800.

Cap screw has a convex head, usually hexagonal, designed to be driven by a spanner or wrench.
Wood screw has a tapered shaft allowing it to penetrate undrilled wood.
Machine screw has a cylindrical shaft and fits into a nut or a tapped hole, a small bolt.
Self-tapping screw has a cylindrical shaft and a sharp thread that cuts its own hole, often used in sheet metal or plastic.
Drywall screw is a specialized self-tapping screw with a cylindrical shaft that has proved to have uses far beyond its original application.
Set screw has no head, and is designed to be inserted flush with or below the surface of the workpiece.
Double-ended screw is a wood-screw with two pointed ends and no head, used for making hidden joints between two pieces of wood.
Shapes of Screw Head
Pan head: disc with chamfered outer edge.

1936
Phillips-head screw
Henry Phillips, Inventor

"It's not a bug; it's a feature." That first-line defense of programmers everywhere also applies to the low-tech Phillips-head screw. Do-it-yourselfers hate the distinctive fastener for its tendency to "cam-out," or slip, when plied with a screwdriver. But it was that intentional design flaw that made the Phillips almost impossible for assembly-line workers to overscrew, a feature that endeared it to automakers, who were its first adopters. Although the product, patented in 1936, quickly became the standard for a variety of industrial and consumer uses, its inventor, Henry Phillips, never manufactured a single screw. Instead, he set up the Phillips Screw Co. to license his recessed-cross screw design.