A lathe ( / l eɪ ð / ) is a machine tool that rotates a workpiece about an axis of rotation to perform various operations such as cutting , sanding , knurling , drilling , deformation , facing , threading and turning , with tools that are applied to the workpiece to create an object with symmetry about that axis.
112-531: The Holtzapffel dynasty of tool and lathe makers was founded in Long Acre , London by a Strasbourg-born turner, Jean-Jacques Holtzapffel, in 1794. The firm specialized in lathes for ornamental turning but also made a name for its high-quality edge and boring tools. Moving to London from Alsace in 1792, Jean-Jacques worked initially in the workshop of the scientific-instrument maker Jesse Ramsden , anglicizing his name to John Jacob Holtzapffel. In 1794 he set up
224-399: A bearing surface and keeps the screw from being driven deeper than its length; an exception being the set screw (aka grub screw ). The cylindrical portion of the screw from the underside of the head to the tip is called the shank ; it may be fully or partially threaded with the distance between each thread called the pitch . Most screws are tightened by clockwise rotation, which
336-412: A collet inserted into the spindle and secured either by a draw-bar, or by a collet closing cap on the spindle. Suitable collets may also be used to mount square or hexagonal workpieces. In precision toolmaking work such collets are usually of the draw-in variety, where, as the collet is tightened, the workpiece moves slightly back into the headstock, whereas for most repetition work the dead length variety
448-417: A female threaded fastener other than a nut. Sheet-metal screws do not have the chip-clearing flute of self-tapping screws. However, some wholesale vendors do not distinguish between the two kinds. A wood screw is a metal screw used to fix wood, with a sharp point and a tapered thread designed to cut its own thread into the wood. Some screws are driven into intact wood; larger screws are usually driven into
560-429: A pattern for foundries , often from wood, but also plastics. A patternmaker's lathe looks like a heavy wood lathe, often with a turret and either a leadscrew or a rack and pinion to manually position the turret . The turret is used to accurately cut straight lines. They often have a provision to turn very large parts on the other end of the headstock, using a free-standing toolrest. Another way of turning large parts
672-449: 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
784-414: A "compound rest" that attach to the lathe bed and allows the tool to be clamped in place and moved by a screw or lever feed. Graver tools are generally supported by a T-rest, not fixed to a cross slide or compound rest. The work is usually held in a collet, but high-precision 3 and 6-jaw chucks are also commonly employed. Common spindle bore sizes are 6 mm, 8 mm and 10 mm. The term WW refers to
896-540: A bench or table, but offer such features as tool holders and a screw-cutting gear train are called hobby lathes, and larger versions, "bench lathes" - this term also commonly applied to a special type of high-precision lathe used by toolmakers for one-off jobs. Even larger lathes offering similar features for producing or modifying individual parts are called "engine lathes". Lathes of these types do not have additional integral features for repetitive production, but rather are used for individual part production or modification as
1008-405: A cantilevered tool-rest. At one end of the bed (almost always the left, as the operator faces the lathe) is a headstock. The headstock contains high-precision spinning bearings. Rotating within the bearings is a horizontal axle, with an axis parallel to the bed, called the spindle . Spindles are often hollow and have an interior Morse taper on the spindle nose (i.e., facing to the right / towards
1120-401: A computer are CNC lathes . Lathes with the spindle mounted in a vertical configuration, instead of horizontal configuration, are called vertical lathes or vertical boring machines. They are used where very large diameters must be turned, and the workpiece (comparatively) is not very long. A lathe with a tool post that can rotate around a vertical axis, so as to present different tools towards
1232-404: A hardened steel center, which is used to support long thin shafts while turning, or to hold drill bits for drilling axial holes in the work piece. Many other uses are possible. Metalworking lathes have a carriage (comprising a saddle and apron) topped with a cross-slide, which is a flat piece that sits crosswise on the bed and can be cranked at right angles to the bed. Sitting atop the cross slide
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#17328839963041344-402: A hole narrower than the screw thread, and cut the thread in the wood. Early wood screws were made by hand, with a series of files, chisels, and other cutting tools, and these can be spotted easily by noting the irregular spacing and shape of the threads, as well as file marks remaining on the head of the screw and in the area between threads. Many of these screws had a blunt end, completely lacking
1456-501: 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 as arguably the most important drivers, caused great increase in the use of threaded fasteners. Standardization of threadforms began almost immediately, but it
1568-471: A nearby forge. The screw mill was not a commercial success; it eventually failed due to competition from the lower-cost, gimlet-pointed screw, and ceased operations in 1836. The American 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
1680-409: A pilot hole in a substrate, and most are classed as screws. Mating threads are formed in the substrate as these fasteners are driven in. Fasteners with a non-tapered shank are generally designed to mate with a nut or to be driven into a tapped hole, and most would be classed as bolts , although some are thread-forming (eg. taptite ) and some authorities would treat some as screws when they are used with
1792-407: A running center is a cup center , which is a cone of metal surrounded by an annular ring of metal that decreases the chances of the workpiece splitting. A circular metal plate with even spaced holes around the periphery, mounted to the spindle, is called an "index plate". It can be used to rotate the spindle to a precise angle, then lock it in place, facilitating repeated auxiliary operations done to
1904-419: A screw may form its own thread. The difference between a screw and a bolt is that the latter is designed to be tightened or released by torquing a nut . The screw head on one end has a milled slot that commonly requires a tool to transfer the twisting force. Common tools for driving screws include screwdrivers , wrenches , coins and hex keys . The head is usually larger than the body, which provides
2016-618: A standard (in about 1841) was the English engineer Sir Joseph Whitworth . Whitworth screw sizes are still used, both for repairing old machinery and where a coarser thread than the metric fastener thread is required. Whitworth became British Standard Whitworth , abbreviated to BSW (BS 84:1956) and the British Standard Fine (BSF) thread was introduced in 1908 because the Whitworth thread was too coarse for some applications. The thread angle
2128-543: A tool-making partnership in Long Acre with Francis Rousset, trading under the name of John Holtzapffel. From 1804 he was in partnership with the Mannheim-born Johann Georg Deyerlein until the latter's death in 1826, trading under the name Holtzapffel & Deyerlein . Holtzapffel sold his first lathe in June 1795, for £25-4s-10d, an enormous price at the time. All of Holtzapffel's lathes were numbered and by
2240-456: A variety of screw head shapes. A few varieties of screw are manufactured with a break-away head, which snaps off when adequate torque is applied, to prevent removal after fitting, often to avoid tampering. The international standards for metric externally threaded fasteners are ISO 898-1 for property classes produced from carbon steels and ISO 3506-1 for property classes produced from corrosion resistant steels. There are many standards governing
2352-441: A very high production rate, and produces virtually no waste material. Slotted head screws require an extra step to cut the slot in the head; this is done on a slotting machine . These machines are essentially stripped down milling machines designed to process as many blanks as possible. The blanks are then polished again prior to threading. The threads are usually produced via thread rolling ; however, some are cut . The workpiece
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#17328839963042464-461: A wide range of sizes and shapes, depending upon their application. Some common styles are diamond, round, square and triangular. Screw A screw is an externally helical threaded fastener capable of being tightened or released by a twisting force ( torque ) to the head . The most common uses of screws are to hold objects together and there are many forms for a variety of materials. Screws might be inserted into holes in assembled parts or
2576-425: A working height. A lathe may be small and sit on a workbench or table, not requiring a stand. Almost all lathes have a bed, which is almost always a horizontal beam, although CNC lathes commonly have an inclined or vertical beam for a bed to ensure that swarf , or chips, falls free of the bed. Woodturning lathes specialized for turning large bowls often have no bed or tail stock, merely a free-standing headstock and
2688-452: Is 0.25–3 in (6.35–76.20 mm) in diameter . In 1991, responding to an influx of counterfeit fasteners, Congress passed PL 101-592, the "Fastener Quality Act". As a result, the ASME B18 committee re-wrote B18.2.1, renaming finished hex bolts to hex cap screw – a term that had existed in common usage long before, but was now also being codified as an official name for
2800-491: Is 1/4" Whitworth (20 tpi) and for medium/large format cameras is 3/8" Whitworth (16 tpi). It is also used for microphone stands and their appropriate clips, again in both sizes, along with "thread adapters" to allow the smaller size to attach to items requiring the larger thread. Note that while 1/4" UNC bolts fit 1/4" BSW camera tripod bushes, yield strength is reduced by the different thread angles of 60° and 55° respectively. British Association (BA) screw threads, named after
2912-441: Is 60°. Traditionally, a hard dead center is used together with suitable lubricant in the tailstock to support the workpiece. In modern practice the dead center is frequently replaced by a running center , as it turns freely with the workpiece—usually on ball bearings—reducing the frictional heat, especially important at high speeds. When clear facing a long length of material it must be supported at both ends. This can be achieved by
3024-408: Is a misnomer ) or French wood screw (Scandinavia) are large wood screws. Lag screws are used to lag together lumber framing, to lag machinery feet to wood floors, and for other heavy carpentry applications. The attributive modifier lag came from an early principal use of such fasteners: the fastening of lags such as barrel staves and other similar parts. These fasteners are "screws" according to
3136-706: Is a spanner (UK usage) or wrench (US usage), while a nut setter is used with a power screw driver. Modern screws employ a wide variety of screw drive designs , each requiring a different kind of tool to drive in or extract them. The most common screw drives are the slotted and Phillips in the US; hex, Robertson, and Torx are also common in some applications, and Pozidriv has almost completely replaced Phillips in Europe. Some types of drive are intended for automatic assembly in mass-production of such items as automobiles. More exotic screw drive types may be used in situations where tampering
3248-424: Is a sliding bed, which can slide away from the headstock and thus open up a gap in front of the headstock for large parts. In a metalworking lathe , metal is removed from the workpiece using a hardened cutting tool , which is usually fixed to a solid moveable mounting, either a tool-post or a turret, which is then moved against the workpiece using handwheels or computer-controlled motors. These cutting tools come in
3360-523: Is an ancient tool. The earliest evidence of a lathe dates back to Ancient Egypt around 1300 BC. There is also tenuous evidence for its existence at a Mycenaean Greek site, dating back as far as the 13th or 14th century BC. Clear evidence of turned artifacts have been found from the 6th century BC: fragments of a wooden bowl in an Etruscan tomb in Northern Italy as well as two flat wooden dishes with decorative turned rims from modern Turkey . During
3472-399: Is called a screwdriver . A power tool that does the same job is a power screwdriver ; power drills may also be used with screw-driving attachments. Where the holding power of the screwed joint is critical, torque-measuring and torque-limiting screwdrivers are used to ensure sufficient but not excessive force is developed by the screw. The hand tool for driving hex head threaded fasteners
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3584-567: Is called a right-hand thread . Screws with a left-hand thread are used in exceptional cases, such as where the screw will be subject to counterclockwise torque , which would tend to loosen a right-hand screw. For this reason, the left-side pedal of a bicycle has a left-hand thread . The screw mechanism is one of the six classical simple machines defined by Renaissance scientists. Fasteners had become widespread involving concepts such as dowels and pins, wedging, mortises and tenons , dovetails , nailing (with or without clenching
3696-428: Is driven either by foot power from a treadle and flywheel or by a belt or gear drive from a power source such as electric motor or overhead line shafts. In most modern lathes this power source is an integral electric motor, often either in the headstock, to the left of the headstock, or beneath the headstock, concealed in the stand. In addition to the spindle and its bearings, the headstock often contains parts to convert
3808-452: Is duplicating or copying lathe. Some types of them are known as Blanchard lathe, after Thomas Blanchard . This type of lathe was able to create shapes identical to a standard pattern and it revolutionized the process of gun stock making in the 1820s when it was invented. The Hermitage Museum , Russia displays the copying lathe for ornamental turning : making medals and guilloche patterns, designed by Andrey Nartov , 1721. Used to make
3920-453: Is marked similarity in the two prefaces and elsewhere. Ronalds and Charles also collaborated on developing lathe accessories. When Charles Holtzapffel died in 1847 his wife Amelia ran the business until 1853. John Jacob II, the son of Charles and Amelia, was head of the firm from 1867 until 1896. A nephew of John Jacob II, George William Budd (1857–1924) became head of the firm in 1896. His son John George Holtzapffel Budd (1888–1968) later ran
4032-437: Is preferred, as this ensures that the position of the workpiece does not move as the collet is tightened. A soft workpiece (e.g., wood) may be pinched between centers by using a spur drive at the headstock, which bites into the wood and imparts torque to it. A soft dead center is used in the headstock spindle as the work rotates with the centre. Because the centre is soft it can be trued in place before use. The included angle
4144-609: Is the outer diameter of the thread. The tapped hole (or nut) into which the screw fits, has an internal diameter which is the size of the screw minus the pitch of the thread. Thus, an M6 screw, which has a pitch of 1 mm, is made by threading a 6 mm shank, and the nut or threaded hole is made by tapping threads into a hole of 5 mm diameter (6 mm − 1 mm). Metric hexagon bolts, screws and nuts are specified, for example, in International Standards ISO 4014, ISO 4017, and ISO 4032. The following table lists
4256-423: Is the tensile stress at which the bolt fails. Tensile yield strength is the stress at which the bolt will yield in tension across the entire section of the bolt and receive a permanent set (an elongation from which it will not recover when the force is removed) of 0.2% offset strain . Proof strength is the usable strength of the fastener. Tension testing of a bolt up to the proof load should not cause permanent set of
4368-400: Is then cold headed , which is a cold working process. Heading produces the head of the screw. The shape of the die in the machine dictates what features are pressed into the screw head; for example a flat head screw uses a flat die. For more complicated shapes two heading processes are required to get all of the features into the screw head. This production method is used because heading has
4480-399: Is then tumble finished with wood and leather media to do final cleaning and polishing. For most screws, a coating, such as electroplating with zinc ( galvanizing ) or applying black oxide , is applied to prevent corrosion. Threaded fasteners either have a tapered shank or a non-tapered shank. Fasteners with tapered shanks are designed to either be driven into a substrate directly or into
4592-627: Is undesirable, such as in electronic appliances that should not be serviced by the home repair person. There are many systems for specifying the dimensions of screws, but in much of the world the ISO metric screw thread preferred series has displaced the many older systems. Other relatively common systems include the British Standard Whitworth , BA system (British Association) , and the Unified Thread Standard . The basic principles of
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4704-507: Is usually a smaller fastener (less than 1 ⁄ 4 inch (6.35 mm) in diameter) threaded the entire length of its shank that usually has a recessed drive type (slotted, Phillips, etc.), usually intended to screw into a pre-formed thread, either a nut or a threaded (tapped) hole, unlike a wood or self-tapping screw. Machine screws are also made with socket heads (see above), often referred to as socket-head machine screws. ASME standard B18.2.1-1996 specifies hex cap screws whose size range
4816-431: Is usually another slide called a compound rest, which provides two additional axes of motion, rotary and linear. Atop that sits a toolpost, which holds a cutting tool , which removes material from the workpiece. There may or may not be a leadscrew , which moves the cross-slide along the bed. Woodturning and metal spinning lathes do not have cross-slides, but rather have banjos , which are flat pieces that sit crosswise on
4928-816: The Machinery's Handbook criteria, and the obsolescent term "lag bolt" has been replaced by "lag screw" in the Handbook . However, based on tradition many tradesmen continue to refer to them as "bolts", because, like head bolts, they are large, with hex or square heads that require a wrench, socket, or specialized bit to turn. The head is typically an external hex. Metric hex-headed lag screws are covered by DIN 571. Inch square-headed and hex-headed lag screws are covered by ASME B18.2.1. A typical lag screw can range in diameter from 4 to 20 mm or #10 to 1.25 in (4.83 to 31.75 mm), and lengths from 16 to 200 mm or 1 ⁄ 4 to 6 in (6.35 to 152.40 mm) or longer, with
5040-504: The United States , but is also extensively used in Canada and occasionally in other countries. The size of a UTS screw is described using the following format: X-Y , where X is the nominal size (the hole or slot size in standard manufacturing practice through which the shank of the screw can easily be pushed) and Y is the threads per inch (TPI). For sizes 1 ⁄ 4 inch and larger
5152-520: The Warring States period in China , c. 400 BC , the ancient Chinese used rotary lathes to sharpen tools and weapons on an industrial scale. The first known painting showing a lathe dates to the 3rd century BC in ancient Egypt . Pliny later describes the use of a lathe for turning soft stone in his Natural History (Book XXX, Chapter 44). Precision metal-cutting lathes were developed during
5264-412: The industrial revolution . They are key components of micrometers and lathes. There are three steps in manufacturing a screw: heading , thread rolling , and coating . Screws are normally made from wire , which is supplied in large coils, or round bar stock for larger screws. The wire or rod is then cut to the proper length for the type of screw being made; this workpiece is known as a blank . It
5376-427: The 15th century, if known at all. The metal screw did not become a common fastener until machine tools for mass production developed toward the end of the 18th century. This development blossomed in the 1760s and 1770s. along two separate paths that soon converged : The first path was pioneered by brothers Job and William Wyatt of Staffordshire , UK, who patented in 1760 a machine that one might today best call
5488-406: 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 become characteristic of modern industry but which 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
5600-410: 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
5712-577: The 1st century BC, wooden screws were commonly used throughout the Mediterranean world in screw presses for pressing olive oil from olives and for pressing juice from grapes in winemaking . The first documentation of the screwdriver is in the medieval Housebook of Wolfegg Castle , a manuscript written sometime between 1475 and 1490. However they probably did not become widespread until after 1800, once threaded fasteners had become commodified. Metal screws used as fasteners were rare in Europe before
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#17328839963045824-462: The ASME B18 standard. Lug bolt and head bolts are other terms that refer to fasteners that are designed to be threaded into a tapped hole that is in part of the assembly and so based on the Machinery's Handbook distinction they would be screws. Here common terms are at variance with Machinery's Handbook distinction. Lag screws (US) or coach screws (UK, Australia, and New Zealand) (also referred to as lag bolts or coach bolts , although this
5936-673: The British Association for Advancement of Science, were devised in 1884 and standardised in 1903. Screws were described as "2BA", "4BA" etc., the odd numbers being rarely used, except in equipment made prior to the 1970s for telephone exchanges in the UK. This equipment made extensive use of odd-numbered BA screws, in order—it may be suspected—to reduce theft. BA threads are specified by British Standard BS 93:1951 "Specification for British Association (B.A.) screw threads with tolerances for sizes 0 B.A. to 16 B.A." While not related to ISO metric screws,
6048-579: The ISO metric screw thread are defined in international standard ISO 68-1 and preferred combinations of diameter and pitch are listed in ISO 261. The smaller subset of diameter and pitch combinations commonly used in screws, nuts and bolts is given in ISO 262 . The most commonly used pitch value for each diameter is the coarse pitch . For some diameters, one or two additional fine pitch variants are also specified, for special applications such as threads in thin-walled pipes. ISO metric screw threads are designated by
6160-531: The United States are still inch based. The numbers stamped on the head of the bolt are referred to the grade of the bolt used in certain application with the strength of a bolt. High-strength steel bolts usually have a hexagonal head with an ISO strength rating (called property class ) stamped on the head. And the absence of marking/number indicates a lower grade bolt with low strength. The property classes most often used are 5.8, 8.8, and 10.9. The number before
6272-496: The WW (Webster Whitcomb) bed, a truncated triangular prism (found only on 8 and 10 mm watchmakers' lathes); and the continental D-style bar bed (used on both 6 mm and 8 mm lathes by firms such as Lorch and Star). Other bed designs have been used, such as a triangular prism on some Boley 6.5 mm lathes, and a V-edged bed on IME's 8 mm lathes. Smaller metalworking lathes that are larger than jewelers' lathes and can sit on
6384-800: The Webster/Whitcomb collet and lathe, invented by the American Watch Tool Company of Waltham, Massachusetts. Most lathes commonly referred to as watchmakers lathes are of this design. In 1909, the American Watch Tool company introduced the Magnus type collet (a 10-mm body size collet) using a lathe of the same basic design, the Webster/Whitcomb Magnus. (F.W.Derbyshire, Inc. retains the trade names Webster/Whitcomb and Magnus and still produces these collets. ) Two bed patterns are common:
6496-453: The alternative, faceplate dogs may be used to secure the work to the faceplate. A workpiece may be mounted on a mandrel , or circular work clamped in a three- or four-jaw chuck . For irregular shaped workpieces it is usual to use a four jaw (independent moving jaws) chuck. These holding devices mount directly to the lathe headstock spindle. In precision work, and in some classes of repetition work, cylindrical workpieces are usually held in
6608-449: The bed or ways, or to the rest. The swing determines the diametric size of the object which is capable of being turned in the lathe; anything larger would interfere with the bed. This limit is called the swing of the bed. The swing of the rest is the size which will rotate above the rest, which lies upon the bed.") from the notion that the work 'swings' from the centre upon which it is mounted. This makes more sense with odd-shaped work but as
6720-407: The bed) by which work-holding accessories may be mounted to the spindle. Spindles may also have arrangements for work-holding on the left-hand end of the spindle with other tooling arrangements for particular tasks. (i.e., facing away from the main bed) end, or may have a hand-wheel or other accessory mechanism on their outboard end. Spindles are powered and impart motion to the workpiece. The spindle
6832-409: The bed. The position of a banjo can be adjusted by hand; no gearing is involved. Ascending vertically from the banjo is a tool-post, at the top of which is a horizontal tool-rest. In woodturning, hand tools are braced against the tool-rest and levered into the workpiece. In metal spinning, the further pin ascends vertically from the tool-rest and serves as a fulcrum against which tools may be levered into
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#17328839963046944-540: The best-known design being the Potter's wheel . Most suitably equipped metalworking lathes can also be used to produce most solids of revolution , plane surfaces and screw threads or helices . Ornamental lathes can produce three-dimensional solids of incredible complexity. The workpiece is usually held in place by either one or two centers , at least one of which can typically be moved horizontally to accommodate varying workpiece lengths. Other work-holding methods include clamping
7056-409: The bible of ornamental turning. The first volume was published in 1843, but the final two volumes were completed and published after his death by his son, John Jacob Holtzapffel (1836–1897). There is some evidence to suggest that Francis Ronalds assisted Charles in the early stages of preparing the treatise. Typeset sections survive of an unfinished "Turner's Manual" that Ronalds wrote in 1837 and there
7168-413: The bolt and should be conducted on actual fasteners rather than calculated. If a bolt is tensioned beyond the proof load, it may behave in plastic manner due to yielding in the threads and the tension preload may be lost due to the permanent plastic deformations. When elongating a fastener prior to reaching the yield point, the fastener is said to be operating in the elastic region; whereas elongation beyond
7280-400: The bows screwed to the frame with 00-72 (pronounced double ought – seventy two) size screws. To calculate the major diameter of "ought" size screws count the number of 0's and multiply this number by 0.013 and subtract from 0.060. For example, the major diameter of a 000-72 screw thread is .060 – (3 x .013) = 0.060 − 0.039 = .021 inches. For most size screws there are multiple TPI available, with
7392-598: The business. By the early twentieth century, ornamental turning was going out of fashion, and the firm sold its last lathe in 1928. The cover of the Holtzapffel c. 1903 catalogue shows medals won at world's fairs and exhibitions in 1851 (3), 1862 , 1884, 1885 ( International Inventions Exhibition ), 1887. Lathe Lathes are used in woodturning , metalworking , metal spinning , thermal spraying , reclamation, and glass-working. Lathes can be used to shape pottery ,
7504-436: The capacity of the work that they may hold. Usually large work is held at both ends either using a chuck or other drive in the headstock and a centre in the tailstock. To maximise size, turning between centres allows the work to be as close to the headstock as possible and is used to determine the longest piece the lathe will turn: when the base of the tailstock is aligned with the end of the bed. The distance between centres gives
7616-445: The coarse threads of a wood-screw or sheet-metal-screw threadform (but larger). The materials are usually carbon steel substrate with a coating of zinc galvanization (for corrosion resistance). The zinc coating may be bright yellow (electroplated), or dull gray ( hot-dip galvanized ). Bone screws have the medical use of securing broken bones in living humans and animals. As with aerospace and nuclear power, medical use involves some of
7728-437: 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
7840-531: 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 remained
7952-518: The headstock (and the workpiece) are turret lathes . A lathe equipped with indexing plates, profile cutters, spiral or helical guides, etc., so as to enable ornamental turning is an ornamental lathe . Various combinations are possible: for example, a vertical lathe can have CNC capabilities as well (such as a CNC VTL ). Lathes can be combined with other machine tools, such as a drill press or vertical milling machine . These are usually referred to as combination lathes . Woodworking lathes are
8064-471: The headstock is the tailstock , sometimes referred to as the loose head, as it can be positioned at any convenient point on the bed by sliding it to the required area. The tail-stock contains a barrel, which does not rotate, but can slide in and out parallel to the axis of the bed and directly in line with the headstock spindle. The barrel is hollow and usually contains a taper to facilitate the gripping of various types of tooling. Its most common uses are to hold
8176-475: The headstock, or at right angles, but gently. When a workpiece is mounted with a certain axis of rotation, worked, then remounted with a new axis of rotation, this is referred to as "eccentric turning" or "multi-axis turning". The result is that various cross sections of the workpiece are rotationally symmetric, but the workpiece as a whole is not rotationally symmetric. This technique is used for camshafts, various types of chair legs. Lathes are usually 'sized' by
8288-409: The highest technology for fasteners; excellent performance, longevity, and quality are required, and reflected in prices. Bone screws are often made of relatively non-reactive stainless steel or titanium, and they often have advanced features such as conical threads, multistart threads, cannulation (hollow core), and proprietary screw drive types, some not seen outside of these applications. There are
8400-479: The internal-wrenching hexagon drive ( hex socket ) shortly followed in 1911. In the early 1930s American Henry F. Phillips popularized the Phillips-head screw , with a cross-shaped internal drive. Later improved -head screws were developed, more compatible with screwdrivers not of the exactly right head size: Pozidriv and Supadriv . Phillips screws and screwdrivers are to some extent compatible with those for
8512-664: The inventor of many subsequent improvements to the lathe worked as an apprentice in Verbruggen's workshop in Woolwich. During the Industrial Revolution , mechanized power generated by water wheels or steam engines was transmitted to the lathe via line shafting, allowing faster and easier work. Metalworking lathes evolved into heavier machines with thicker, more rigid parts. Between the late 19th and mid-20th centuries, individual electric motors at each lathe replaced line shafting as
8624-414: The lathe is most often used with cylindrical work, it is useful to know the maximum diameter of work the lathe will hold. This is simply the value of the swing (or centre height above the bed) multiplied by two. For some reason, in the U.S. swing is assumed to be diameter but this is incorrect. To be clear on size, it is better, therefore, to describe the dimension as 'centre height above the bed'. As parts of
8736-519: The lathe reduce capacity, measurements such as 'swing over cross slide' or other named parts can be found. The smallest lathes are "jewelers lathes" or "watchmaker lathes", which, though often small enough to be held in one hand are normally fastened to a bench. There are rare and even smaller mini lathes made for precision cutting. The workpieces machined on a jeweler's lathe are often metal, but other softer materials can also be machined. Jeweler's lathes can be used with hand-held "graver" tools or with
8848-508: The lead up to the Industrial Revolution and were critical to the manufacture of mechanical inventions of that period. Some of the earliest examples include a version with a mechanical cutting tool-supporting carriage and a set of gears by Russian engineer Andrey Nartov in 1718 and another with a slide-rest shown in a 1717 edition of the French Encyclopédie . The slide-rest was a particularly important development because it constrains
8960-547: The left side of the headstock, where are no rails and therefore more clearance. In this configuration, the piece can be shaped inside and out. A specific curved tool-rest may be used to support tools while shaping the inside. Further detail can be found on the woodturning page. Most woodworking lathes are designed to be operated at a speed of between 200 and 1,400 revolutions per minute, with slightly over 1,000 rpm considered optimal for most such work, and with larger workpieces requiring lower speeds. One type of specialized lathe
9072-410: The letter M followed by the major diameter of the thread in millimetres (e.g. M8 ). If the thread does not use the normal coarse pitch (e.g. 1.25 mm in the case of M8), then the pitch in millimeters is also appended with a multiplication sign (e.g. "M8×1" if the screw thread has an outer diameter of 8 mm and advances by 1 mm per 360° rotation). The nominal diameter of a metric screw
9184-483: The machinist happened to need on any given day). In 1821 Hardman Philips built the first screw factory in the United States – on Moshannon Creek, near Philipsburg – for the manufacture of blunt metal screws. An expert in screw manufacture, Thomas Lever, was brought over from England to run the factory. The mill used steam and water power, with hardwood charcoal as fuel. The screws were made from wire prepared by "rolling and wire drawing apparatus" from iron manufactured at
9296-559: The marks showing the Charing Cross address and those showing the address in the Haymarket. John's son, Charles Holtzapffel (1806–1847) joined the firm in 1827, at around which time the firm became known as Holtzapffel & Co . Charles continued to run the business after his father's death. He set about writing a treatise entitled Turning and Mechanical Manipulation , eventually running to some 2,750 pages, and which came to be regarded as
9408-405: The material and mechanical properties of imperial sized externally threaded fasteners. Some of the most common consensus standards for grades produced from carbon steels are ASTM A193, ASTM A307, ASTM A354, ASTM F3125, and SAE J429. Some of the most common consensus standards for grades produced from corrosion resistant steels are ASTM F593 & ASTM A193. The hand tool used to drive in most screws
9520-406: The maximum length of work the lathe will officially hold. It is possible to get slightly longer items in if the tailstock overhangs the end of the bed but this is an ill-advised practice. Purchasing an extension or larger bed would be a wise alternative. The other dimension of the workpiece is how far off-centre it can be. This is known as the 'swing' ("The distance from the head center of a lathe to
9632-422: The metal shaping tools. The tool-rest is usually removed during sanding, as it may be unsafe to have the operators hands between it and the spinning wood. Many woodworking lathes can also be used for making bowls and plates. The bowl or plate needs only to be held at the bottom by one side of the lathe. It is usually attached to a metal face plate attached to the spindle. With many lathes, this operation happens on
9744-632: The most common being designated a Unified Coarse Thread (UNC or UN) and Unified Fine Thread (UNF or UF). Note: In countries other than the United States and Canada, the ISO Metric Screw Thread System is primarily used today. Unlike most other countries the United States and Canada still use the Unified (Inch) Thread System. However, both are moving over to the ISO Metric System. It is estimated that approximately 60% of screw threads in use in
9856-819: The motion of the cutting tool to generate accurate cylindrical or conical surfaces, unlike earlier lathes that involved freehand manipulation of the tool. By the 1770s, precision lathes became practical and well-known. A slide-rest is clearly shown in a 1772 edition of the Encyclopédie and during that same year a horse-powered cannon boring lathe was installed in the Royal Arsenal in Woolwich , England by Jan Verbruggen . Cannon bored by Verbruggen's lathe were stronger and more accurate than their predecessors and saw service in American Revolutionary War . Henry Maudslay ,
9968-464: The motor speed into various spindle speeds . Various types of speed-changing mechanism achieve this, from a cone pulley or step pulley, to a cone pulley with back gear (which is essentially a low range, similar in net effect to the two-speed rear of a truck), to an entire gear train similar to that of a manual-shift automotive transmission . Some motors have electronic rheostat-type speed controls, which obviates cone pulleys or gears. The counterpoint to
10080-644: The nail ends), forge welding , and many kinds of binding with cord made of leather or fiber, using many kinds of knots . The screw was one of the last of the simple machines to be invented. It first appeared in Mesopotamia during the Neo-Assyrian period (911-609) BC, and then later appeared in Ancient Egypt and Ancient Greece where it was described by the Greek mathematician Archytas of Tarentum (428–350 BC). By
10192-502: The newer types, but with the risk of damaging the heads of tightly fastened screws. 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, and represented one of the central technical advances, along with flat surfaces, that enabled
10304-404: The oldest variety, apart from pottery wheels. All other varieties are descended from these simple lathes. An adjustable horizontal metal rail, the tool-rest, between the material and the operator accommodates the positioning of shaping tools, which are usually hand-held. After shaping, it is common practice to press and slide sandpaper against the still-spinning object to smooth the surface made with
10416-444: The point is the ultimate tensile strength in MPa divided by 100. The number after the point is the multiplier ratio of yield strength to ultimate tensile strength. For example, a property class 5.8 bolt has a nominal (minimum) ultimate tensile strength of 500 MPa, and a tensile yield strength of 0.8 times ultimate tensile strength or 0.8 (500) = 400 MPa. Ultimate tensile strength
10528-404: The power source. Beginning in the 1950s, servomechanisms were applied to the control of lathes and other machine tools via numerical control, which often was coupled with computers to yield computerized numerical control (CNC) . Today manually controlled and CNC lathes coexist in the manufacturing industries. A lathe may or may not have legs, which sit on the floor and elevate the lathe bed to
10640-478: The primary role. Lathes of this size that are designed for mass manufacture, but not offering the versatile screw-cutting capabilities of the engine or bench lathe, are referred to as "second operation" lathes. Lathes with a very large spindle bore and a chuck on both ends of the spindle are called "oil field lathes". Fully automatic mechanical lathes, employing cams and gear trains for controlled movement, are called screw machines . Lathes that are controlled by
10752-399: The relationship given in these standards between the thread size and the maximum width across the hexagonal flats (wrench size): In addition, the following non-preferred intermediate sizes are specified: Bear in mind that these are just examples and the width across flats is different for structural bolts, flanged bolts, and also varies by standards organization. The first person to create
10864-418: The rolling process does not cut the grain of the metal. A self-tapping screw is designed to cut its own thread, usually in a fairly soft metal or plastic, in the same way as a wood screw (wood screws are actually self-tapping, but not referred to as such). ASME standards specify a variety of machine screws (aka stove bolts ) in diameters ranging up to 0.75 in (19.05 mm). A machine screw or bolt
10976-498: The same diameter and pitch as ISO M6, the threads have different forms and are not compatible. BA threads are still common in some niche applications. Certain types of fine machinery, such as moving-coil meters and clocks, tend to have BA threads wherever they are manufactured. BA sizes were also used extensively in aircraft, especially those manufactured in the United Kingdom. BA sizing is still used in railway signalling, mainly for
11088-748: The sharp tapered point on nearly all modern wood screws. Some wood screws were made with cutting dies as early as the late 1700s (possibly even before 1678 when the book content was first published in parts). Eventually, lathes were used to manufacture wood screws, with the earliest patent being recorded in 1760 in England. During the 1850s, swaging tools were developed to provide a more uniform and consistent thread. Screws made with these tools have rounded valleys with sharp and rough threads. Once screw turning machines were in common use, most commercially available wood screws were produced with this method. These cut wood screws are almost invariably tapered, and even when
11200-495: The size is given as a fraction; for sizes less than this an integer is used, ranging from 0 to 16. The integer sizes can be converted to the actual diameter by using the formula 0.060 + (0.013 × number). For example, a #4 screw is 0.060 + (0.013 × 4) = 0.060 + 0.052 = 0.112 inches in diameter. There are also screw sizes smaller than "0" (zero or ought). The sizes are 00, 000, 0000 which are usually referred to as two ought, three ought, and four ought. Most eyeglasses have
11312-563: The sizes were actually defined in metric terms, a 0BA thread having a 6 mm diameter and 1 mm pitch. Other threads in the BA series are related to 0BA in a geometric series with the common factors 0.9 and 1.2. For example, a 4BA thread has pitch p = 0.9 4 {\displaystyle \scriptstyle p=0.9^{4}} mm (0.65 mm) and diameter 6 p 1.2 {\displaystyle \scriptstyle 6p^{1.2}} mm (3.62 mm). Although 0BA has
11424-426: The tapered shank is not obvious, they can be discerned because the threads do not extend past the diameter of the shank. Such screws are best installed after drilling a pilot hole with a tapered drill bit. The majority of modern wood screws, except for those made of brass, are formed on thread rolling machines. These screws have a constant diameter and threads with a larger diameter than the shank and are stronger because
11536-481: The termination of electrical equipment and cabling. BA threads are extensively used in Model Engineering where the smaller hex head sizes make scale fastenings easier to represent. As a result, many UK Model Engineering suppliers still carry stocks of BA fasteners up to typically 8BA and 10BA. 5BA is also commonly used as it can be threaded onto 1/8 rod. The Unified Thread Standard (UTS) is most commonly used in
11648-458: The time he died in 1835, about 1,600 had been sold. The business was located at 64 Charing Cross , London from 1819 until 1901 when the site was required "for building purposes". The firm then moved to 13 and 14 New Bond Street, and was in premises in the Haymarket from 1907 to 1930. The firm's marks come in a wide array of styles. Among the most noteworthy are the marks at the time of John Jacob Holtzapffel's partnership with Johann Georg Deyerlein,
11760-556: The use of a traveling or fixed steady . If a steady is not available, the end face being worked on may be supported by a dead (stationary) half center. A half center has a flat surface machined across a broad section of half of its diameter at the pointed end. A small section of the tip of the dead center is retained to ensure concentricity. Lubrication must be applied at this point of contact and tail stock pressure reduced. A lathe carrier or lathe dog may also be employed when turning between two centers. In woodturning, one variation of
11872-468: The work about the axis of rotation using a chuck or collet , or to a faceplate , using clamps or dog clutch . Of course, lathes can also complete milling operations by installing special lathe milling fixtures. Examples of objects that can be produced on a lathe include screws , candlesticks , gun barrels , cue sticks , table legs, bowls , baseball bats , pens , musical instruments (especially woodwind instruments ), and crankshafts . The lathe
11984-440: The workpiece, via tools, at a right angle to the axis of rotation, without fear that the workpiece may break loose. When a workpiece is fixed only to the spindle at the headstock end, the work is said to be "face work". When a workpiece is supported in this manner, less force may be applied to the workpiece, via tools, at a right angle to the axis of rotation, lest the workpiece rip free. Thus, most work must be done axially, towards
12096-431: The workpiece. Other accessories, including items such as taper turning attachments, knurling tools, vertical slides, fixed and traveling steadies, etc., increase the versatility of a lathe and the range of work it may perform. When a workpiece is fixed between the headstock and the tail-stock, it is said to be "between centers". When a workpiece is supported at both ends, it is more stable, and more force may be applied to
12208-403: The workpiece. Unless a workpiece has a taper machined onto it which perfectly matches the internal taper in the spindle, or has threads which perfectly match the external threads on the spindle (two conditions which rarely exist), an accessory must be used to mount a workpiece to the spindle. A workpiece may be bolted or screwed to a faceplate , a large, flat disk that mounts to the spindle. In
12320-406: The yield point is referred to as operating in the plastic region of the bolt material. If a bolt is loaded in tension beyond its proof strength, the yielding at the net root section of the bolt will continue until the entire section begins to yield and it has exceeded its yield strength. If tension increases, the bolt fractures at its ultimate strength. Mild steel bolts have property class 4.6, which
12432-405: Was 55°, and the depth and pitch varied with the diameter of the thread (i.e., the bigger the bolt, the coarser the thread). Spanners for Whitworth bolts are marked with the size of the bolt, not the distance across the flats of the screw head. The most common use of a Whitworth pitch nowadays is in all UK scaffolding . Additionally, the standard photographic tripod thread, which for small cameras
12544-501: 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 mass production of wood screws (metal screws for fixing wood) in a specialized, single-purpose, high-volume-production machine tool; and the low-count, toolroom -style production of machine screws or bolts (V-thread) with easy selection among various pitches (whatever
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