Screw - History

History

While a recent hypothesis attributes the Archimedes' screw to Sennacherib, King of Assyria, archaeological finds and pictorial evidence only appear in the Hellenistic period and the standard view holds the device to be a Greek invention, most probably by the 3rd century BC polymath Archimedes himself. Though resembling a screw, this is not a screw in the usual sense of the word.

The screw was later described by the Greek mathematician Archytas of Tarentum (428–350 BC). By the 1st century BC, wooden screws were commonly used throughout the Mediterranean world in devices such as oil and wine presses. Metal screws used as fasteners were rare in Europe before the 15th century, if known at all.

Rybczynski has shown that handheld screwdrivers (formerly called "turnscrews" in English, in more direct parallel to their original French name, tournevis) have existed since medieval times (the 1580s at the latest), although they probably did not become truly widespread until after 1800, once threaded fasteners themselves had become commodified, as detailed below.

There were many forms of fastening in use before threaded fasteners became widespread. They tended to involve carpentry and smithing rather than machining, and they involved concepts such as dowels and pins, wedging, mortises and tenons, dovetails, nailing (with or without clenching the nail ends), forge welding, and many kinds of binding with cord made of leather or fiber, using many kinds of knots. Prior to the mid-19th century, cotter pins or pin bolts, and "clinch bolts" (now called rivets), were used in shipbuilding.

The metal screw did not become a common fastener until machine tools for their mass production were developed toward the end of the 18th century. This development blossomed in the 1760s and 1770s along two separate paths that soon converged: the mass production of wood screws in a specialized, single-purpose, high-volume-production machine tool; and the low-count, toolroom-style production of machine screws (V-thread) with easy selection among various pitches (whatever the machinist happened to need on any given day).

The first path was pioneered by brothers Job and William Wyatt of Staffordshire, UK, who patented in 1760 a machine that we might today best call a screw machine of an early and prescient sort. It made use of a leadscrew to guide the cutter to produce the desired pitch, and the slot was cut with a rotary file while the main spindle held still (presaging live tools on lathes 250 years later). Not until 1776 did the Wyatt brothers have a wood-screw factory up and running. Their enterprise failed, but new owners soon made it prosper, and in the 1780s they were producing 16,000 screws a day with only 30 employees—the kind of industrial productivity and output volume that would later be characteristic of modern industry but was revolutionary at the time.

Meanwhile, English instrument maker Jesse Ramsden (1735–1800) was working on the toolmaking and instrument-making end of the screw-cutting problem, and in 1777 he invented the first satisfactory screw-cutting lathe. The British engineer Henry Maudslay (1771–1831) gained fame by popularizing such lathes with his screw-cutting lathes of 1797 and 1800, containing the trifecta of leadscrew, slide rest, and change-gear gear train, all in the right proportions for industrial machining. In a sense he unified the paths of the Wyatts and Ramsden and did for machine screws what had already been done for wood screws, i.e., significant easing of production spurring commodification. His firm would remain a leader in machine tools for decades afterward. A misquoting of James Nasmyth popularized the notion that Maudslay had invented the slide rest, but this was incorrect; however, his lathes helped to popularize it.

These developments of the 1760–1800 era, with the Wyatts and Maudslay being arguably the most important drivers, caused great increase in the use of threaded fasteners. Standardization of threadforms began almost immediately, but it was not quickly completed; it has been an evolving process ever since. Further improvements to the mass production of screws continued to push unit prices lower and lower for decades to come, throughout the 19th century.

The development of the turret lathe (1840s) and of automatic screw machines derived from it (1870s) drastically reduced the unit cost of threaded fasteners by increasingly automating the machine tool control. This cost reduction spurred ever greater use of screws.

Throughout the 19th century, the most commonly used forms of screw head (that is, drive types) were simple internal-wrenching straight slots and external-wrenching squares and hexagons. These were easy to machine and served most applications adequately. Rybczynski describes a flurry of patents for alternative drive types in the 1860s through 1890s, but explains that these were patented but not manufactured due to the difficulties and expense of doing so at the time. In 1908, Canadian P. L. Robertson was the first to make the internal-wrenching square socket drive a practical reality by developing just the right design (slight taper angles and overall proportions) to allow the head to be stamped easily but successfully, with the metal cold forming as desired rather than being sheared or displaced in unwanted ways. Practical manufacture of the internal-wrenching hexagon drive (hex socket) shortly followed in 1911. In the early 1930s, the Phillips-head screw was invented by Henry F. Phillips.

Threadform standardization further improved in the late 1940s, when the ISO metric screw thread and the Unified Thread Standard were defined.

Precision screws, for controlling motion rather than fastening, developed around the turn of the 19th century, were one of the central technical advances, along with flat surfaces, that enabled the industrial revolution. They are key components of micrometers and lathes.