{"history":[],"article":{"id":"226b0575-9a9c-464c-8c97-a33aaa72aee4","title":"Metal lathe","slug":"metal-lathe","content":":::summary\n:::\n\n# \nIn [machining](https://bliptext.com/articles/machining), a **metal lathe** or **metalworking lathe** is a large class of [lathes](https://bliptext.com/articles/lathe) designed for precisely [machining](https://bliptext.com/articles/machining) relatively hard materials.\nThey were originally designed to machine [metals](https://bliptext.com/articles/metal); however, with the advent of [plastics](https://bliptext.com/articles/plastic) and other materials, and with their inherent versatility, they are used in a wide range of applications, and a broad range of materials.\nIn machining [jargon](https://bliptext.com/articles/jargon), where the larger context is already understood, they are usually simply called lathes, or else referred to by more-specific subtype names ([toolroom lathe](https://bliptext.com/articles/), [turret lathe](https://bliptext.com/articles/), etc.).\nThese rigid [machine tools](https://bliptext.com/articles/machine-tool) remove material from a [rotating](https://bliptext.com/articles/rotation) workpiece via the (typically [linear](https://bliptext.com/articles/linear-motion)) movements of various cutting tools, such as [tool bits](https://bliptext.com/articles/tool-bit) and [drill bits](https://bliptext.com/articles/drill-bit).\n# [Center lathe with digital read out and chuck guard. Size is 460 mm diameter x 1000 mm between centers | upload.wikimedia.org/wikipedia/commons/6/68/HwacheonCentreLathe///460x1000.jpg]\n\n# Construction\nThe design of lathes can vary greatly depending on the intended application; however, basic features are common to most types.\nThese machines consist of (at the least) a headstock, bed, carriage, and tailstock.\nBetter machines are solidly constructed with broad bearing surfaces (slide-ways) for stability, and manufactured with great precision.\nThis helps ensure the components manufactured on the machines can meet the required tolerances and repeatability.\n\n## Headstock\nThe **headstock (H1)** houses the main spindle **(H4)**, speed change mechanism **(H2, H3)**, and change gears **(H10)**.\nThe headstock is required to be made as robust as possible due to the cutting forces involved, which can distort a lightly built housing, and induce [harmonic](https://bliptext.com/articles/harmonic) vibrations that will transfer through to the workpiece, reducing the quality of the finished workpiece.\nThe main spindle is generally hollow to allow long bars to extend through to the work area.\nThis reduces preparation and waste of material.\nThe spindle runs in precision bearings and is fitted with some means of attaching workholding devices such as [chucks](https://bliptext.com/articles/chuck-engineering) or [faceplates](https://bliptext.com/articles/lathe-faceplate).\nThis end of the spindle usually also has an included [taper](https://bliptext.com/articles/machine-tapers), frequently a Morse [taper](https://bliptext.com/articles/machine-tapers), to allow the insertion of hollow tubular (Morse standard) [taper](https://bliptext.com/articles/machine-tapers)s to reduce the size of the [taper](https://bliptext.com/articles/machine-tapers)ed hole, and permit use of [centers](https://bliptext.com/articles/lathe-center).\nOn older machines ('50s) the spindle was directly driven by a [flat belt](https://bliptext.com/articles/flat-belt) [pulley](https://bliptext.com/articles/pulley) with lower speeds available by manipulating the bull gear.\nLater machines use a gear box driven by a dedicated electric motor.\nA fully 'geared head' allows the operator to select suitable speeds entirely through the gearbox.\n# [Headstock assembly with legend, numbers and text within the description refer to those in the image | upload.wikimedia.org/wikipedia/commons/6/6f/HwacheonCentreLathe-headstock-mask///legend.jpg]\n\n## Beds\nThe **bed** is a robust base that connects to the headstock and permits the carriage and [tailstock](https://bliptext.com/articles/tailstock) to be moved parallel with the axis of the spindle.\nThis is facilitated by hardened and ground **bedways** which restrain the carriage and tailstock in a set track.\nThe carriage travels by means of a [rack and pinion](https://bliptext.com/articles/rack-and-pinion) system.\nThe [leadscrew](https://bliptext.com/articles/leadscrew) of accurate pitch, drives the carriage holding the cutting tool via a gearbox driven from the headstock.\nTypes of beds include inverted \"V\" beds, flat beds, and combination \"V\" and flat beds.\n\"V\" and combination beds are used for precision and light duty work, while flat beds are used for heavy duty work.\nWhen a lathe is installed, the first step is to level it, which refers to making sure the bed is not twisted or bowed.\nThere is no need to make the machine exactly horizontal, but it must be entirely untwisted to achieve accurate cutting geometry.\nA precision level is a useful tool for identifying and removing any twist.\nIt is advisable also to use such a level along the bed to detect bending, in the case of a lathe with more than four mounting points.\nIn both instances the level is used as a comparator rather than an absolute reference.\n\n## Feed and lead screws\nThe **feedscrew (H8)** is a long [driveshaft](https://bliptext.com/articles/driveshaft) that allows a series of gears to drive the carriage mechanisms.\nThese gears are located in the **apron** of the carriage.\nBoth the feedscrew and **leadscrew (H7)** are driven by either the **change gears** (on the quadrant) or an intermediate gearbox known as a **quick change gearbox** **(H6)** or [Norton gearbox](https://bliptext.com/articles/norton-gearbox).\nThese intermediate gears allow the correct ratio and direction to be set for cutting [threads](https://bliptext.com/articles/screw) or [worm gears](https://bliptext.com/articles/worm-gear).\nTumbler gears (operated by **H5**) are provided between the spindle and gear train along with a **quadrant** plate that enables a gear train of the correct ratio and direction to be introduced.\nThis provides a constant relationship between the number of turns the spindle makes, to the number of turns the leadscrew makes.\nThis ratio allows screwthreads to be cut on the workpiece without the aid of a [die](https://bliptext.com/articles/taps-and-dies).\nSome lathes have only one leadscrew that serves all carriage-moving purposes.\nFor screw cutting, a **half nut** is engaged to be driven by the leadscrew's thread; and for general power feed, a key engages with a keyway cut into the leadscrew to drive a pinion along a rack that is mounted along the lathe bed.\nThe leadscrew will be manufactured to either [imperial](https://bliptext.com/articles/imperial-unit) or [metric](https://bliptext.com/articles/metre) standards and will require a conversion ratio to be introduced to create thread forms from a different family.\nTo accurately convert from one thread form to the other requires a 127-tooth gear, or on lathes not large enough to mount one, an approximation may be used.\nMultiples of 3 and 7 giving a ratio of 63:1 can be used to cut fairly loose threads.\nThis conversion ratio is often built into the quick change gearboxes.\nThe precise ratio required to convert a lathe with an Imperial (inch) leadscrew to metric (millimeter) threading is 100 / 127 = 0.7874... . The best approximation with the fewest total teeth is very often 37 / 47 = 0.7872... . This transposition gives a constant -0.020 percent error over all customary and model-maker's metric pitches (0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.60, 0.70, 0.75, 0.80, 1.00, 1.25, 1.50, 1.75, 2.00, 2.50, 3.00, 3.50, 4.00, 4.50, 5.00, 5.50 and 6.00 mm).\n\n## Carriage\nIn its simplest form the **carriage** holds the tool bit and moves it longitudinally (turning) or perpendicularly (facing) under the control of the operator.\nThe operator moves the carriage manually via the handwheel **(5a)** or automatically by engaging the feed shaft with the carriage feed mechanism **(5c)**.\nThis provides some relief for the operator as the movement of the carriage becomes power assisted.\nThe handwheels **(2a, 3b, 5a)** on the carriage and its related slides are usually calibrated, both for ease of use and to assist in making reproducible cuts.\nThe carriage typically comprises a top casting, known as the **saddle (4)**, and a side casting, known as the **apron (5)**.\n# [The parts of a lathe carriage:

Toolpost
Compound/top-slide
Cross-slide
Saddle
Apron

See text for more details. | upload.wikimedia.org/wikipedia/commons/1/13/HwacheonCentreLathe-carriage-mask///legend.jpg]\n\n### Cross-slide\nThe **cross-slide** **(3)** rides on the carriage and has a feedscrew which travels at right angles to the main spindle axis.\nThis permits [facing](https://bliptext.com/articles/facing-machining) operations to be performed, and the depth of cut to be adjusted.\nThis feedscrew can be engaged, through a gear train, to the feed shaft (mentioned previously) to provide automated 'power feed' movement to the cross-slide.\nOn most lathes, only one direction can be engaged at a time as an interlock mechanism will shut out the second gear train.\nCross-slide handwheels are usually marked in terms of the part's diameter, so one graduation representing .001 inches of diameter corresponds to .0005 inches of cross-slide motion.\n\n### Compound rest\nThe **compound rest** (or **top slide**) **(2)** is usually where the tool post is mounted.\nIt provides a smaller amount of movement (less than the cross-slide) along its axis via another feedscrew.\nThe compound rest axis can be adjusted independently of the carriage or cross-slide.\nIt is used for turning tapers, to control depth of cut when [screwcutting](https://bliptext.com/articles/screw-cutting-lathe) or precision facing, or to obtain finer feeds (under manual control) than the feed shaft permits.\nUsually, the compound rest has a protractor marked in its base **(2b)**, enabling the operator to adjust its axis to precise angles.\nThe slide rest (as the earliest forms of carriage were known) can be traced to the fifteenth century.\nIn 1718 the tool-supporting slide rest with a set of gears was introduced by a Russian inventor [Andrey Nartov](https://bliptext.com/articles/andrey-nartov) and had limited usage in the Russian industry.\nThe first fully documented, all-metal slide rest lathe was invented by [Jacques de Vaucanson](https://bliptext.com/articles/jacques-de-vaucanson) around 1751.\nIt was described in the [Encyclopédie](https://bliptext.com/articles/encyclop-die) a long time before Maudslay invented and perfected his version.\nIt is likely that Maudslay was not aware of Vaucanson's work, since his first versions of the slide rest had many errors that were not present in the Vaucanson lathe.\nIn the eighteenth century the slide rest was also used on French [ornamental turning](https://bliptext.com/articles/ornamental-turning) lathes.\nThe suite of gun boring mills at the [Royal Arsenal](https://bliptext.com/articles/royal-arsenal), [Woolwich](https://bliptext.com/articles/woolwich), in the 1780s by the [Verbruggan family](https://bliptext.com/articles/verbruggan-family) also had slide rests.\nThe story has long circulated that [Henry Maudslay](https://bliptext.com/articles/henry-maudslay) invented it, but he did not (and never claimed so).\nThe legend that Maudslay invented the slide rest originated with [James Nasmyth](https://bliptext.com/articles/james-nasmyth), who wrote ambiguously about it in his Remarks on the Introduction of the Slide Principle, 1841; later writers misunderstood, and propagated the error.\nHowever, Maudslay did help to disseminate the idea widely.\nIt is highly probable that he saw it when he was working at the Arsenal as a boy.\nIn 1794, whilst he was working for [Joseph Bramah](https://bliptext.com/articles/joseph-bramah), he made one, and when he had his own workshop used it extensively in the lathes he made and sold there.\nCoupled with the network of engineers he trained, this ensured the slide rest became widely known and copied by other lathe makers, and so diffused throughout British engineering workshops.\nA practical and versatile [screw-cutting lathe](https://bliptext.com/articles/screw-cutting-lathe) incorporating the trio of leadscrew, change gears, and slide rest was Maudslay's most important achievement.\n\n### Toolpost\nThe tool bit is mounted in the **toolpost** **(1)** which may be of the American lantern style, traditional four-sided square style, or a quick-change style such as the multi-fix arrangement pictured.\nThe advantage of a quick change set-up is to allow an unlimited number of tools to be used (up to the number of holders available) rather than being limited to one tool with the lantern style, or to four tools with the four-sided type.\nInterchangeable tool holders allow all tools to be preset to a center height that does not change, even if the holder is removed from the machine.\n\n## Tailstock\nThe **[tailstock](https://bliptext.com/articles/tailstock)** is a tool (drill), and center mount, opposite the headstock.\nThe spindle **(T5)** does not rotate but does travel longitudinally under the action of a leadscrew and handwheel **(T1)**.\nThe spindle includes a [taper](https://bliptext.com/articles/machine-tapers) to hold drill bits, centers and other [tooling](https://bliptext.com/articles/chuck-engineering).\nThe tailstock can be positioned along the bed and clamped **(T6)** in position as dictated by the work piece.\nThere is also provision to offset the tailstock **(T4)** from the spindles axis, this is useful for turning small tapers, and when re-aligning the tailstock to the axis of the bed.\nThe image shows a reduction gear box **(T2)** between the handwheel and spindle, where large drills may necessitate the extra leverage.\nThe tool bit is normally made of HSS, cobalt steel or carbide.\n# [Tailstock with legend, numbers and text within the description refer to those in the image | upload.wikimedia.org/wikipedia/commons/3/3d/HwacheonCentreLathe-tailstock-mask///legend.jpg]\n\n## Steady, follower and other rests\nLong workpieces often need to be supported in the middle, as cutting tools can push (bend) the work piece away from where the centers can support them, because cutting metal produces tremendous forces that tend to vibrate or even bend the workpiece.\nThis extra support can be provided by a ****steady** rest** (also called a **steady**, a fixed **steady**, a ****center** rest**, or sometimes, confusingly, a **center**).\nIt stands stationary from a rigid mounting on the bed, and it supports the workpiece at the rest's center, typically with three contact points 120° apart.\nA ****follower** rest** (also called a **follower** or a **travelling steady**) is similar, but it is mounted to the carriage rather than the bed, which means that as the tool bit moves, the ****follower** rest** \"follows along\" (because they are both rigidly connected to the same moving carriage).\nFollower rests can provide support that directly counteracts the springing force of the tool bit, right at the region of the workpiece being cut at any moment.\nIn this respect they are analogous to a [box tool](https://bliptext.com/articles/tool-bit).\nAny rest transfers some workpiece geometry errors from base ([bearing surface](https://bliptext.com/articles/bearing-surface)) to processing surface.\nIt depends on the rest design.\nFor minimum transfer rate **correcting rests** are used.\nRest rollers typically cause some additional geometry errors on the processing surface.\n\n# Types of metal lathes\nThere are many variants of lathes within the [metalworking](https://bliptext.com/articles/metalworking) field.\nSome variations are not all that obvious, and others are more a niche area.\nFor example, a **centering lathe** is a dual head machine where the work remains fixed and the heads move towards the workpiece and machine a center drill hole into each end.\nThe resulting workpiece may then be used \"between centers\" in another operation.\nThe usage of the term **metal lathe** may also be considered somewhat outdated these days.\nPlastics and other composite materials are in wide use and, with appropriate modifications, the same principles and techniques may be applied to their machining as that used for metal.\n\n## Center lathe / engine lathe / bench lathe\nThe terms **center lathe**, **engine lathe**, and **bench lathe** all refer to a basic type of lathe that may be considered the archetypical class of metalworking lathe most often used by the general [machinist](https://bliptext.com/articles/machinist) or machining hobbyist.\nThe name bench lathe implies a version of this class small enough to be mounted on a workbench (but still full-featured, and larger than [mini-lathes or micro-lathes](https://bliptext.com/articles/)).\nThe construction of a center lathe is detailed above, but depending on the year of manufacture, size, price range or desired features, even these lathes can vary widely between models.\nEngine lathe is the name applied to a traditional late-19th-century or 20th-century lathe with automatic feed to the cutting tool, as opposed to early lathes which were used with hand-held tools, or lathes with manual feed only.\nThe usage of \"engine\" here is in the mechanical-device sense, not the prime-mover sense, as in the [steam engines](https://bliptext.com/articles/steam-engine) which were the standard industrial power source for many years.\nThe works would have one large steam engine which would provide power to all the machines via a [line shaft](https://bliptext.com/articles/line-shaft) system of belts.\nTherefore, early engine lathes were generally 'cone heads', in that the spindle usually had attached to it a multi-step pulley called a cone pulley designed to accept a flat belt.\nDifferent spindle speeds could be obtained by moving the flat belt to different steps on the cone pulley.\nCone-head lathes usually had a countershaft ([layshaft](https://bliptext.com/articles/layshaft)) on the back side of the cone which could be engaged to provide a lower set of speeds than was obtainable by direct belt drive.\nThese gears were called back gears.\nLarger lathes sometimes had two-speed back gears which could be shifted to provide a still lower set of speeds.\nWhen electric motors started to become common in the early 20th century, many cone-head lathes were converted to electric power.\nAt the same time the state of the art in [gear](https://bliptext.com/articles/gear) and [bearing](https://bliptext.com/articles/bearing-mechanical) practice was advancing to the point that manufacturers began to make fully [gear](https://bliptext.com/articles/gear)ed headstocks, using [gear](https://bliptext.com/articles/gear)boxes analogous to [automobile transmissions](https://bliptext.com/articles/transmission-mechanics) to obtain various spindle speeds and feed rates while transmitting the higher amounts of [power](https://bliptext.com/articles/power-physics) needed to take full advantage of [high-speed steel](https://bliptext.com/articles/high-speed-steel) tools.\nCutting tools evolved once again, with the introduction of man-made carbides, and became widely introduced to general industry in the 1970s.\nEarly carbides were attached to toolholders by brazing them into a machined 'nest' in the tool holders.\nLater designs allowed tips to be replaceable and multi faceted, allowing them to be reused.\nCarbides tolerate much higher machining speeds without wearing.\nThis has led to machining times shortening, and therefore production growing.\nThe demand for faster and more powerful lathes controlled the direction of lathe development.\nThe availability of inexpensive electronics has again changed the way speed control may be applied by allowing continuously variable motor speed from the maximum down to almost zero RPM.\nThis had been tried in the late 19th century but was not found satisfactory at the time.\nSubsequent improvements in electric circuitry have made it viable again.\n# [A typical center lathe | upload.wikimedia.org/wikipedia/commons/9/95/Metal///lathe.png]\n\n## Toolroom lathe\nA [toolroom](https://bliptext.com/articles/toolroom) lathe is a lathe optimized for [toolroom](https://bliptext.com/articles/toolroom) work.\nIt is essentially just a top-of-the-line [center lathe](https://bliptext.com/articles/), with all of the best optional features that may be omitted from less expensive models, such as a collet closer, taper attachment, and others.\nThe bed of a toolroom lathe is generally wider than that of a standard center lathe.\nThere has also been an implication over the years of selective assembly and extra fitting, with every care taken in the building of a toolroom model to make it the smoothest-running, most-accurate version of the machine that can be built.\nHowever, within one brand, the quality difference between a regular model and its corresponding toolroom model depends on the builder and in some cases has been partly marketing psychology.\nFor name-brand machine tool builders who made only high-quality tools, there wasn't necessarily any lack of quality in the base-model product for the \"luxury model\" to improve upon.\nIn other cases, especially when comparing different brands, the quality differential between (1) an entry-level center lathe built to compete on price, and (2) a toolroom lathe meant to compete only on quality and not on price, can be objectively demonstrated by measuring TIR, vibration, etc. In any case, because of their fully ticked-off option list and (real or implied) higher quality, toolroom lathes are more expensive than entry-level center lathes.\n\n## Turret lathe and capstan lathe\n[Turret lathes and capstan lathes](https://bliptext.com/articles/turret-lathe) are members of a class of lathes that are used for repetitive production of duplicate parts (which by the nature of their cutting process are usually [interchangeable](https://bliptext.com/articles/interchangeable-parts)).\nIt evolved from earlier lathes with the addition of the turret, which is an [indexable](https://bliptext.com/articles/indexing-motion) tool holder that allows multiple cutting operations to be performed, each with a different cutting tool, in easy, rapid succession, with no need for the operator to perform setup tasks in between (such as installing or uninstalling tools) nor to control the toolpath.\n(The latter is due to the toolpath being controlled by the machine, either in [jig](https://bliptext.com/articles/jig-tool)-like fashion via the mechanical limits placed on it by the turret's slide and stops, or via computer-directed servo mechanisms on [CNC](https://bliptext.com/articles/computer-numerical-control) lathes.)\nThere is a tremendous variety of turret lathe and capstan lathe designs, reflecting the variety of work that they do.\n\n## Gang-tool lathe\nA gang-tool lathe is one that has a row of tools set up on its cross-slide, which is long and flat and is similar to a [milling machine](https://bliptext.com/articles/milling-machine) table.\nThe idea is essentially the same as with turret lathes: to set up multiple tools and then easily index between them for each part-cutting cycle.\nInstead of being rotary like a turret, the indexable tool group is linear.\n\n## Multispindle lathe\n**Multispindle lathes** have more than one spindle and automated control (whether via [cams](https://bliptext.com/articles/cam-mechanism) or CNC).\nThey are production machines specializing in high-volume production.\nThe smaller types are usually called **[screw machines](https://bliptext.com/articles/screw-machine-automatic-lathe)**, while the larger variants are usually called **automatic chucking machines**, **automatic **chuckers****, or simply **chuckers**.\nScrew machines usually work from bar stock, while chuckers automatically chuck up individual blanks from a magazine.\nTypical minimum profitable production lot size on a screw machine is in the thousands of parts due to the large setup time.\nOnce set up, a screw machine can rapidly and efficiently produce thousands of parts on a continuous basis with high accuracy, low cycle time, and very little human intervention.\n(The latter two points drive down the unit cost per interchangeable part much lower than could be achieved without these machines.)\n\n## CNC lathe / CNC turning center\n[Computer numerical controlled](https://bliptext.com/articles/computer-numerical-control) (CNC) lathes are rapidly replacing the older production lathes (multispindle, etc.) due to their ease of set up, operation, repeatability and accuracy.\nA CNC Turning Lathe is a Computer Controlled piece of machinery.\nIt allows basic machining operations such as turning and drilling to be carried out as on a conventional lathe.\nThey are designed to use modern [carbide](https://bliptext.com/articles/tungsten-carbide) tooling and fully use modern processes.\nThe part may be designed and the tool paths programmed by the [CAD/CAM](https://bliptext.com/articles/computer-aided-technologies) process or manually by the programmer, and the resulting file uploaded to the machine, and once set and trialled the machine will continue to turn out parts under the occasional supervision of an operator.\nThe machine is controlled electronically via a computer menu style interface, the program may be modified and displayed at the machine, along with a simulated view of the process.\nThe setter/operator needs a high level of skill to perform the process.\nHowever, the knowledge base is broader compared to the older production machines where intimate knowledge of each machine was considered essential.\nThese machines are often set and operated by the same person, where the operator will supervise a small number of machines (cell).\nThe design of a CNC lathe varies with different manufacturers, but they all have some common elements.\nThe turret holds the tool holders and indexes them as needed, the spindle holds the workpiece and there are slides that let the turret move in multiple axes simultaneously.\nThe machines are often totally enclosed, due in large part to [occupational health and safety](https://bliptext.com/articles/occupational-safety-and-health) (OH&S) issues.\nWith rapid growth in this industry, different CNC lathe manufacturers use different user interfaces which sometimes makes it difficult for operators as they have to be acquainted with them.\nWith the advent of cheap computers, free operating systems such as [Linux](https://bliptext.com/articles/linux), and [open source](https://bliptext.com/articles/open-source) CNC software, the entry price of CNC machines has plummeted.\n# [CNC lathe with milling capabilities | upload.wikimedia.org/wikipedia/commons/0/07/MoriSeikiLathe.jpg]\n# [An example turned vase and view of the tool turret | upload.wikimedia.org/wikipedia/commons/c/c1/MoriSeiki-examples.jpg]\n\n## Swiss-style lathe / Swiss turning center\nA **Swiss-style lathe** is a specific design of lathe providing extreme accuracy (sometimes holding tolerances as small as a few tenths of a thousandth of an inch—a few [micrometers](https://bliptext.com/articles/micrometers)).\nA Swiss-style lathe holds the workpiece with both a [collet](https://bliptext.com/articles/collet) and a guide [bushing](https://bliptext.com/articles/bushing-bearing).\nThe collet sits behind the guide bushing, and the tools sit in front of the guide bushing, holding stationary on the Z axis.\nTo cut lengthwise along the part, the tools will move in and the material itself will move back and forth along the Z axis.\nThis allows all the work to be done on the material near the guide bushing where it is more rigid, making them ideal for working on slender workpieces as the part is held firmly with little chance of deflection or vibration occurring.\nThis style of lathe is commonly used under CNC control.\nMost CNC Swiss-style lathes today use one or two main spindles plus one or two back spindles (secondary spindles).\nThe main spindle is used with the guide bushing for the main machining operations.\nThe secondary spindle is located behind the part, aligned on the Z axis.\nIn simple operation it picks up the part as it is cut off, and accepts it for second operations, then ejects it into a bin, eliminating the need to have an operator manually change each part, as is often the case with standard CNC turning centers.\nThis makes them very efficient, as these machines are capable of fast cycle times, producing simple parts in one cycle (i.e., no need for a second machine to finish the part with second operations), in as little as 10–15 seconds.\nThis makes them ideal for large production runs of small-diameter parts.\n# [A view inside the enclosure of a CNC Swiss-style lathe/screw machine | upload.wikimedia.org/wikipedia/commons/0/08/CNC///Swiss///turn///001.jpg]\n\n### Swiss-style Lathes and Live Tooling\nAs many Swiss lathes incorporate a secondary spindle, or 'sub-spindle', they also incorporate **'live tooling** '.\nLive tools are rotary cutting tools that are powered by a small motor independently of the spindle motor.\nLive tools increase the intricacy of components that can be manufactured by the Swiss lathe.\nFor instance, automatically producing a part with a hole drilled perpendicular to the main axis (the axis of rotation of the spindles) is very economical with live tooling, and similarly uneconomical if done as a secondary operation after machining by the Swiss lathe is complete.\nA 'secondary operation' is a machining operation requiring a partially completed part to be secured in a second machine to complete the manufacturing process.\nGenerally, advanced CAD/CAM software uses live tools in addition to the main spindles so that most parts that can be drawn by a CAD system can actually be manufactured by the machines that the CAD/CAM software support.\n\n## Combination lathe / 3-in-1 machine\nA **combination lathe**, often known as a **3-in-1 machine**, introduces drilling or milling operations into the design of the lathe.\nThese machines have a milling column rising up above the lathe bed, and they utilize the carriage and topslide as the X and Y axes for the milling column.\nThe 3-in-1 name comes from the idea of having a lathe, milling machine, and [drill press](https://bliptext.com/articles/drill-press) all in one affordable machine tool.\nThese are exclusive to the hobbyist and [MRO](https://bliptext.com/articles/maintenance-repair-and-operations) markets, as they inevitably involve compromises in size, features, rigidity, and precision in order to remain affordable.\nNevertheless, they meet the demand of their niche quite well, and are capable of high accuracy given enough time and skill.\nThey may be found in smaller, non-machine-oriented businesses where the occasional small part must be machined, especially where the exacting tolerances of expensive toolroom machines, besides being unaffordable, would be overkill for the application from an engineering perspective.\n\n## Mini-lathe and micro-lathe\nMini-lathes and [micro-lathes](https://bliptext.com/articles/micro-lathe) are miniature versions of a general-purpose center lathe (engine lathe).\nThey typically only handle work of 3 to 7 in diameter (in other words, 1.5 to 3.5 in radius).\nThey are small and affordable lathes for the home workshop or MRO shop.\nThe same advantages and disadvantages apply to these machines as explained earlier regarding [3-in-1 machines](https://bliptext.com/articles/).\nAs found elsewhere in English-language orthography, there is variation in the styling of the prefixes in these machines' names.\nThey are alternately styled as mini lathe, minilathe, and mini-lathe and as micro lathe, microlathe, and micro-lathe''.\n\n## Brake lathe\nA lathe specialized for the task of resurfacing brake [drums](https://bliptext.com/articles/drum-brake) and [discs](https://bliptext.com/articles/disc-brake) in automotive or truck garages.\n\n## Wheel lathe\nWheel lathes are machines used to manufacture and resurface the wheels of railway [rolling stock](https://bliptext.com/articles/rolling-stock).\nWhen wheels become worn or compromised from excessive use, this tool can be used to re-cut and recondition the wheel.\nThere are a number of different wheel lathes available including underfloor variations for resurfacing wheels that are still attached to the rail car, portable types that are easily transported for emergency wheel repairs, and CNC versions which utilize computer-based operating systems to complete the wheel repair.\n# [Beyer, Peacock & Company Electrically Driven Wheel Lathe, 1906 | upload.wikimedia.org/wikipedia/commons/0/09/Beyer///Peacock///Electrically///Driven///Wheel///Lathe%2C///1906.jpg]\n\n## Pit lathe\nA lathe for large diameter, though short work, built over a recess in the floor to admit the lower part of the workpiece thus allowing the toolrest to stand at the turner's waist height.\nAn example is on display at the London Science Museum, Kensington.\n\n## Vertical lathe\nFor even larger diameter and heavier work, such as pressure vessels or marine engines, the lathe is rotated so it takes the form of a turntable on which parts are placed.\nThis orientation is less convenient for the operator, but makes it easier to support large parts.\nIn the largest, the turntable is installed flush with the floor, with the headstock recessed below, to facilitate loading and unloading workpieces.\nBecause operator access is less of an issue for them, CNC vertical turning machines are more popular than manual vertical lathes.\n\n## Oil country lathe\nSpecialised lathes for machining long workpieces such as segments of drill strings.\nOil country lathes are equipped with large-bore hollow spindles, a second chuck on the opposite side of the headstock, and frequently outboard steadies for supporting long workpieces.\n\n# Feed mechanisms\nVarious feed mechanisms exist to feed cutting tools into the work at a controlled rate.\nThe aim of these mechanisms is to automate part of the production process with the end goal of improving productivity.\n\n## Bar feeder\nA bar feeder feeds a single piece of [bar stock](https://bliptext.com/articles/bar-stock) into the cutting machine.\nAs each part is machined, the cutting tool creates a final cut to separate the part from the bar stock, and the feeder continues to feed the bar for the next part, allowing for continual operation of the machine.\nThere are two types of bar feeds used in lathe machining: Hydrodynamic bar feeds, which rest the bar stock in a series of channels whilst clamping down on the top and bottom of the bar, and hydrostatic bar feeds, which hold the bar stock in a feed tube using pressurized oil.\n\n## Bar loader\nA bar loader is a variation on the bar feeder concept in that multiple pieces of bar stock may be fed into a hopper, and the loader feeds each piece as necessary.","current_revision":null,"created_by":"kACnuQmH5k9Nr5VNVEpVeg7XpvUmMctD","created_at":"2025-01-25T22:12:06.409Z","updated_at":"2025-01-25T22:12:06.409Z","search_vector":"'lath':2 'metal':1","search_content":" \n \n\n# \nIn [machining](https://bliptext.com/articles/machining), a **metal lathe** or **metalworking lathe** is a large class of [lathes](https://bliptext.com/articles/lathe) designed for precisely [machining](https://bliptext.com/articles/machining) relatively hard materials.\nThey were originally designed to machine [metals](https://bliptext.com/articles/metal); however, with the advent of [plastics](https://bliptext.com/articles/plastic) and other materials, and with their inherent versatility, they are used in a wide range of applications, and a broad range of materials.\nIn machining [jargon](https://bliptext.com/articles/jargon), where the larger context is already understood, they are usually simply called lathes, or else referred to by more-specific subtype names ([toolroom lathe](https://bliptext.com/articles/), [turret lathe](https://bliptext.com/articles/), etc.).\nThese rigid [machine tools](https://bliptext.com/articles/machine-tool) remove material from a [rotating](https://bliptext.com/articles/rotation) workpiece via the (typically [linear](https://bliptext.com/articles/linear-motion)) movements of various cutting tools, such as [tool bits](https://bliptext.com/articles/tool-bit) and [drill bits](https://bliptext.com/articles/drill-bit).\n# [Center lathe with digital read out and chuck guard. Size is 460 mm diameter x 1000 mm between centers | upload.wikimedia.org/wikipedia/commons/6/68/HwacheonCentreLathe///460x1000.jpg]\n\n# Construction\nThe design of lathes can vary greatly depending on the intended application; however, basic features are common to most types.\nThese machines consist of (at the least) a headstock, bed, carriage, and tailstock.\nBetter machines are solidly constructed with broad bearing surfaces (slide-ways) for stability, and manufactured with great precision.\nThis helps ensure the components manufactured on the machines can meet the required tolerances and repeatability.\n\n## Headstock\nThe **headstock (H1)** houses the main spindle **(H4)**, speed change mechanism **(H2, H3)**, and change gears **(H10)**.\nThe headstock is required to be made as robust as possible due to the cutting forces involved, which can distort a lightly built housing, and induce [harmonic](https://bliptext.com/articles/harmonic) vibrations that will transfer through to the workpiece, reducing the quality of the finished workpiece.\nThe main spindle is generally hollow to allow long bars to extend through to the work area.\nThis reduces preparation and waste of material.\nThe spindle runs in precision bearings and is fitted with some means of attaching workholding devices such as [chucks](https://bliptext.com/articles/chuck-engineering) or [faceplates](https://bliptext.com/articles/lathe-faceplate).\nThis end of the spindle usually also has an included [taper](https://bliptext.com/articles/machine-tapers), frequently a Morse [taper](https://bliptext.com/articles/machine-tapers), to allow the insertion of hollow tubular (Morse standard) [taper](https://bliptext.com/articles/machine-tapers)s to reduce the size of the [taper](https://bliptext.com/articles/machine-tapers)ed hole, and permit use of [centers](https://bliptext.com/articles/lathe-center).\nOn older machines ('50s) the spindle was directly driven by a [flat belt](https://bliptext.com/articles/flat-belt) [pulley](https://bliptext.com/articles/pulley) with lower speeds available by manipulating the bull gear.\nLater machines use a gear box driven by a dedicated electric motor.\nA fully 'geared head' allows the operator to select suitable speeds entirely through the gearbox.\n# [Headstock assembly with legend, numbers and text within the description refer to those in the image | upload.wikimedia.org/wikipedia/commons/6/6f/HwacheonCentreLathe-headstock-mask///legend.jpg]\n\n## Beds\nThe **bed** is a robust base that connects to the headstock and permits the carriage and [tailstock](https://bliptext.com/articles/tailstock) to be moved parallel with the axis of the spindle.\nThis is facilitated by hardened and ground **bedways** which restrain the carriage and tailstock in a set track.\nThe carriage travels by means of a [rack and pinion](https://bliptext.com/articles/rack-and-pinion) system.\nThe [leadscrew](https://bliptext.com/articles/leadscrew) of accurate pitch, drives the carriage holding the cutting tool via a gearbox driven from the headstock.\nTypes of beds include inverted \"V\" beds, flat beds, and combination \"V\" and flat beds.\n\"V\" and combination beds are used for precision and light duty work, while flat beds are used for heavy duty work.\nWhen a lathe is installed, the first step is to level it, which refers to making sure the bed is not twisted or bowed.\nThere is no need to make the machine exactly horizontal, but it must be entirely untwisted to achieve accurate cutting geometry.\nA precision level is a useful tool for identifying and removing any twist.\nIt is advisable also to use such a level along the bed to detect bending, in the case of a lathe with more than four mounting points.\nIn both instances the level is used as a comparator rather than an absolute reference.\n\n## Feed and lead screws\nThe **feedscrew (H8)** is a long [driveshaft](https://bliptext.com/articles/driveshaft) that allows a series of gears to drive the carriage mechanisms.\nThese gears are located in the **apron** of the carriage.\nBoth the feedscrew and **leadscrew (H7)** are driven by either the **change gears** (on the quadrant) or an intermediate gearbox known as a **quick change gearbox** **(H6)** or [Norton gearbox](https://bliptext.com/articles/norton-gearbox).\nThese intermediate gears allow the correct ratio and direction to be set for cutting [threads](https://bliptext.com/articles/screw) or [worm gears](https://bliptext.com/articles/worm-gear).\nTumbler gears (operated by **H5**) are provided between the spindle and gear train along with a **quadrant** plate that enables a gear train of the correct ratio and direction to be introduced.\nThis provides a constant relationship between the number of turns the spindle makes, to the number of turns the leadscrew makes.\nThis ratio allows screwthreads to be cut on the workpiece without the aid of a [die](https://bliptext.com/articles/taps-and-dies).\nSome lathes have only one leadscrew that serves all carriage-moving purposes.\nFor screw cutting, a **half nut** is engaged to be driven by the leadscrew's thread; and for general power feed, a key engages with a keyway cut into the leadscrew to drive a pinion along a rack that is mounted along the lathe bed.\nThe leadscrew will be manufactured to either [imperial](https://bliptext.com/articles/imperial-unit) or [metric](https://bliptext.com/articles/metre) standards and will require a conversion ratio to be introduced to create thread forms from a different family.\nTo accurately convert from one thread form to the other requires a 127-tooth gear, or on lathes not large enough to mount one, an approximation may be used.\nMultiples of 3 and 7 giving a ratio of 63:1 can be used to cut fairly loose threads.\nThis conversion ratio is often built into the quick change gearboxes.\nThe precise ratio required to convert a lathe with an Imperial (inch) leadscrew to metric (millimeter) threading is 100 / 127 = 0.7874... . The best approximation with the fewest total teeth is very often 37 / 47 = 0.7872... . This transposition gives a constant -0.020 percent error over all customary and model-maker's metric pitches (0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.60, 0.70, 0.75, 0.80, 1.00, 1.25, 1.50, 1.75, 2.00, 2.50, 3.00, 3.50, 4.00, 4.50, 5.00, 5.50 and 6.00 mm).\n\n## Carriage\nIn its simplest form the **carriage** holds the tool bit and moves it longitudinally (turning) or perpendicularly (facing) under the control of the operator.\nThe operator moves the carriage manually via the handwheel **(5a)** or automatically by engaging the feed shaft with the carriage feed mechanism **(5c)**.\nThis provides some relief for the operator as the movement of the carriage becomes power assisted.\nThe handwheels **(2a, 3b, 5a)** on the carriage and its related slides are usually calibrated, both for ease of use and to assist in making reproducible cuts.\nThe carriage typically comprises a top casting, known as the **saddle (4)**, and a side casting, known as the **apron (5)**.\n# [The parts of a lathe carriage: \n Toolpost \n Compound/top-slide \n Cross-slide \n Saddle \n Apron \n See text for more details. | upload.wikimedia.org/wikipedia/commons/1/13/HwacheonCentreLathe-carriage-mask///legend.jpg]\n\n### Cross-slide\nThe **cross-slide** **(3)** rides on the carriage and has a feedscrew which travels at right angles to the main spindle axis.\nThis permits [facing](https://bliptext.com/articles/facing-machining) operations to be performed, and the depth of cut to be adjusted.\nThis feedscrew can be engaged, through a gear train, to the feed shaft (mentioned previously) to provide automated 'power feed' movement to the cross-slide.\nOn most lathes, only one direction can be engaged at a time as an interlock mechanism will shut out the second gear train.\nCross-slide handwheels are usually marked in terms of the part's diameter, so one graduation representing .001 inches of diameter corresponds to .0005 inches of cross-slide motion.\n\n### Compound rest\nThe **compound rest** (or **top slide**) **(2)** is usually where the tool post is mounted.\nIt provides a smaller amount of movement (less than the cross-slide) along its axis via another feedscrew.\nThe compound rest axis can be adjusted independently of the carriage or cross-slide.\nIt is used for turning tapers, to control depth of cut when [screwcutting](https://bliptext.com/articles/screw-cutting-lathe) or precision facing, or to obtain finer feeds (under manual control) than the feed shaft permits.\nUsually, the compound rest has a protractor marked in its base **(2b)**, enabling the operator to adjust its axis to precise angles.\nThe slide rest (as the earliest forms of carriage were known) can be traced to the fifteenth century.\nIn 1718 the tool-supporting slide rest with a set of gears was introduced by a Russian inventor [Andrey Nartov](https://bliptext.com/articles/andrey-nartov) and had limited usage in the Russian industry.\nThe first fully documented, all-metal slide rest lathe was invented by [Jacques de Vaucanson](https://bliptext.com/articles/jacques-de-vaucanson) around 1751.\nIt was described in the [Encyclopédie](https://bliptext.com/articles/encyclop-die) a long time before Maudslay invented and perfected his version.\nIt is likely that Maudslay was not aware of Vaucanson's work, since his first versions of the slide rest had many errors that were not present in the Vaucanson lathe.\nIn the eighteenth century the slide rest was also used on French [ornamental turning](https://bliptext.com/articles/ornamental-turning) lathes.\nThe suite of gun boring mills at the [Royal Arsenal](https://bliptext.com/articles/royal-arsenal), [Woolwich](https://bliptext.com/articles/woolwich), in the 1780s by the [Verbruggan family](https://bliptext.com/articles/verbruggan-family) also had slide rests.\nThe story has long circulated that [Henry Maudslay](https://bliptext.com/articles/henry-maudslay) invented it, but he did not (and never claimed so).\nThe legend that Maudslay invented the slide rest originated with [James Nasmyth](https://bliptext.com/articles/james-nasmyth), who wrote ambiguously about it in his Remarks on the Introduction of the Slide Principle, 1841; later writers misunderstood, and propagated the error.\nHowever, Maudslay did help to disseminate the idea widely.\nIt is highly probable that he saw it when he was working at the Arsenal as a boy.\nIn 1794, whilst he was working for [Joseph Bramah](https://bliptext.com/articles/joseph-bramah), he made one, and when he had his own workshop used it extensively in the lathes he made and sold there.\nCoupled with the network of engineers he trained, this ensured the slide rest became widely known and copied by other lathe makers, and so diffused throughout British engineering workshops.\nA practical and versatile [screw-cutting lathe](https://bliptext.com/articles/screw-cutting-lathe) incorporating the trio of leadscrew, change gears, and slide rest was Maudslay's most important achievement.\n\n### Toolpost\nThe tool bit is mounted in the **toolpost** **(1)** which may be of the American lantern style, traditional four-sided square style, or a quick-change style such as the multi-fix arrangement pictured.\nThe advantage of a quick change set-up is to allow an unlimited number of tools to be used (up to the number of holders available) rather than being limited to one tool with the lantern style, or to four tools with the four-sided type.\nInterchangeable tool holders allow all tools to be preset to a center height that does not change, even if the holder is removed from the machine.\n\n## Tailstock\nThe **[tailstock](https://bliptext.com/articles/tailstock)** is a tool (drill), and center mount, opposite the headstock.\nThe spindle **(T5)** does not rotate but does travel longitudinally under the action of a leadscrew and handwheel **(T1)**.\nThe spindle includes a [taper](https://bliptext.com/articles/machine-tapers) to hold drill bits, centers and other [tooling](https://bliptext.com/articles/chuck-engineering).\nThe tailstock can be positioned along the bed and clamped **(T6)** in position as dictated by the work piece.\nThere is also provision to offset the tailstock **(T4)** from the spindles axis, this is useful for turning small tapers, and when re-aligning the tailstock to the axis of the bed.\nThe image shows a reduction gear box **(T2)** between the handwheel and spindle, where large drills may necessitate the extra leverage.\nThe tool bit is normally made of HSS, cobalt steel or carbide.\n# [Tailstock with legend, numbers and text within the description refer to those in the image | upload.wikimedia.org/wikipedia/commons/3/3d/HwacheonCentreLathe-tailstock-mask///legend.jpg]\n\n## Steady, follower and other rests\nLong workpieces often need to be supported in the middle, as cutting tools can push (bend) the work piece away from where the centers can support them, because cutting metal produces tremendous forces that tend to vibrate or even bend the workpiece.\nThis extra support can be provided by a ****steady** rest** (also called a **steady**, a fixed **steady**, a ****center** rest**, or sometimes, confusingly, a **center**).\nIt stands stationary from a rigid mounting on the bed, and it supports the workpiece at the rest's center, typically with three contact points 120° apart.\nA ****follower** rest** (also called a **follower** or a **travelling steady**) is similar, but it is mounted to the carriage rather than the bed, which means that as the tool bit moves, the ****follower** rest** \"follows along\" (because they are both rigidly connected to the same moving carriage).\nFollower rests can provide support that directly counteracts the springing force of the tool bit, right at the region of the workpiece being cut at any moment.\nIn this respect they are analogous to a [box tool](https://bliptext.com/articles/tool-bit).\nAny rest transfers some workpiece geometry errors from base ([bearing surface](https://bliptext.com/articles/bearing-surface)) to processing surface.\nIt depends on the rest design.\nFor minimum transfer rate **correcting rests** are used.\nRest rollers typically cause some additional geometry errors on the processing surface.\n\n# Types of metal lathes\nThere are many variants of lathes within the [metalworking](https://bliptext.com/articles/metalworking) field.\nSome variations are not all that obvious, and others are more a niche area.\nFor example, a **centering lathe** is a dual head machine where the work remains fixed and the heads move towards the workpiece and machine a center drill hole into each end.\nThe resulting workpiece may then be used \"between centers\" in another operation.\nThe usage of the term **metal lathe** may also be considered somewhat outdated these days.\nPlastics and other composite materials are in wide use and, with appropriate modifications, the same principles and techniques may be applied to their machining as that used for metal.\n\n## Center lathe / engine lathe / bench lathe\nThe terms **center lathe**, **engine lathe**, and **bench lathe** all refer to a basic type of lathe that may be considered the archetypical class of metalworking lathe most often used by the general [machinist](https://bliptext.com/articles/machinist) or machining hobbyist.\nThe name bench lathe implies a version of this class small enough to be mounted on a workbench (but still full-featured, and larger than [mini-lathes or micro-lathes](https://bliptext.com/articles/)).\nThe construction of a center lathe is detailed above, but depending on the year of manufacture, size, price range or desired features, even these lathes can vary widely between models.\nEngine lathe is the name applied to a traditional late-19th-century or 20th-century lathe with automatic feed to the cutting tool, as opposed to early lathes which were used with hand-held tools, or lathes with manual feed only.\nThe usage of \"engine\" here is in the mechanical-device sense, not the prime-mover sense, as in the [steam engines](https://bliptext.com/articles/steam-engine) which were the standard industrial power source for many years.\nThe works would have one large steam engine which would provide power to all the machines via a [line shaft](https://bliptext.com/articles/line-shaft) system of belts.\nTherefore, early engine lathes were generally 'cone heads', in that the spindle usually had attached to it a multi-step pulley called a cone pulley designed to accept a flat belt.\nDifferent spindle speeds could be obtained by moving the flat belt to different steps on the cone pulley.\nCone-head lathes usually had a countershaft ([layshaft](https://bliptext.com/articles/layshaft)) on the back side of the cone which could be engaged to provide a lower set of speeds than was obtainable by direct belt drive.\nThese gears were called back gears.\nLarger lathes sometimes had two-speed back gears which could be shifted to provide a still lower set of speeds.\nWhen electric motors started to become common in the early 20th century, many cone-head lathes were converted to electric power.\nAt the same time the state of the art in [gear](https://bliptext.com/articles/gear) and [bearing](https://bliptext.com/articles/bearing-mechanical) practice was advancing to the point that manufacturers began to make fully [gear](https://bliptext.com/articles/gear)ed headstocks, using [gear](https://bliptext.com/articles/gear)boxes analogous to [automobile transmissions](https://bliptext.com/articles/transmission-mechanics) to obtain various spindle speeds and feed rates while transmitting the higher amounts of [power](https://bliptext.com/articles/power-physics) needed to take full advantage of [high-speed steel](https://bliptext.com/articles/high-speed-steel) tools.\nCutting tools evolved once again, with the introduction of man-made carbides, and became widely introduced to general industry in the 1970s.\nEarly carbides were attached to toolholders by brazing them into a machined 'nest' in the tool holders.\nLater designs allowed tips to be replaceable and multi faceted, allowing them to be reused.\nCarbides tolerate much higher machining speeds without wearing.\nThis has led to machining times shortening, and therefore production growing.\nThe demand for faster and more powerful lathes controlled the direction of lathe development.\nThe availability of inexpensive electronics has again changed the way speed control may be applied by allowing continuously variable motor speed from the maximum down to almost zero RPM.\nThis had been tried in the late 19th century but was not found satisfactory at the time.\nSubsequent improvements in electric circuitry have made it viable again.\n# [A typical center lathe | upload.wikimedia.org/wikipedia/commons/9/95/Metal///lathe.png]\n\n## Toolroom lathe\nA [toolroom](https://bliptext.com/articles/toolroom) lathe is a lathe optimized for [toolroom](https://bliptext.com/articles/toolroom) work.\nIt is essentially just a top-of-the-line [center lathe](https://bliptext.com/articles/), with all of the best optional features that may be omitted from less expensive models, such as a collet closer, taper attachment, and others.\nThe bed of a toolroom lathe is generally wider than that of a standard center lathe.\nThere has also been an implication over the years of selective assembly and extra fitting, with every care taken in the building of a toolroom model to make it the smoothest-running, most-accurate version of the machine that can be built.\nHowever, within one brand, the quality difference between a regular model and its corresponding toolroom model depends on the builder and in some cases has been partly marketing psychology.\nFor name-brand machine tool builders who made only high-quality tools, there wasn't necessarily any lack of quality in the base-model product for the \"luxury model\" to improve upon.\nIn other cases, especially when comparing different brands, the quality differential between (1) an entry-level center lathe built to compete on price, and (2) a toolroom lathe meant to compete only on quality and not on price, can be objectively demonstrated by measuring TIR, vibration, etc. In any case, because of their fully ticked-off option list and (real or implied) higher quality, toolroom lathes are more expensive than entry-level center lathes.\n\n## Turret lathe and capstan lathe\n[Turret lathes and capstan lathes](https://bliptext.com/articles/turret-lathe) are members of a class of lathes that are used for repetitive production of duplicate parts (which by the nature of their cutting process are usually [interchangeable](https://bliptext.com/articles/interchangeable-parts)).\nIt evolved from earlier lathes with the addition of the turret, which is an [indexable](https://bliptext.com/articles/indexing-motion) tool holder that allows multiple cutting operations to be performed, each with a different cutting tool, in easy, rapid succession, with no need for the operator to perform setup tasks in between (such as installing or uninstalling tools) nor to control the toolpath.\n(The latter is due to the toolpath being controlled by the machine, either in [jig](https://bliptext.com/articles/jig-tool)-like fashion via the mechanical limits placed on it by the turret's slide and stops, or via computer-directed servo mechanisms on [CNC](https://bliptext.com/articles/computer-numerical-control) lathes.)\nThere is a tremendous variety of turret lathe and capstan lathe designs, reflecting the variety of work that they do.\n\n## Gang-tool lathe\nA gang-tool lathe is one that has a row of tools set up on its cross-slide, which is long and flat and is similar to a [milling machine](https://bliptext.com/articles/milling-machine) table.\nThe idea is essentially the same as with turret lathes: to set up multiple tools and then easily index between them for each part-cutting cycle.\nInstead of being rotary like a turret, the indexable tool group is linear.\n\n## Multispindle lathe\n**Multispindle lathes** have more than one spindle and automated control (whether via [cams](https://bliptext.com/articles/cam-mechanism) or CNC).\nThey are production machines specializing in high-volume production.\nThe smaller types are usually called **[screw machines](https://bliptext.com/articles/screw-machine-automatic-lathe)**, while the larger variants are usually called **automatic chucking machines**, **automatic **chuckers****, or simply **chuckers**.\nScrew machines usually work from bar stock, while chuckers automatically chuck up individual blanks from a magazine.\nTypical minimum profitable production lot size on a screw machine is in the thousands of parts due to the large setup time.\nOnce set up, a screw machine can rapidly and efficiently produce thousands of parts on a continuous basis with high accuracy, low cycle time, and very little human intervention.\n(The latter two points drive down the unit cost per interchangeable part much lower than could be achieved without these machines.)\n\n## CNC lathe / CNC turning center\n[Computer numerical controlled](https://bliptext.com/articles/computer-numerical-control) (CNC) lathes are rapidly replacing the older production lathes (multispindle, etc.) due to their ease of set up, operation, repeatability and accuracy.\nA CNC Turning Lathe is a Computer Controlled piece of machinery.\nIt allows basic machining operations such as turning and drilling to be carried out as on a conventional lathe.\nThey are designed to use modern [carbide](https://bliptext.com/articles/tungsten-carbide) tooling and fully use modern processes.\nThe part may be designed and the tool paths programmed by the [CAD/CAM](https://bliptext.com/articles/computer-aided-technologies) process or manually by the programmer, and the resulting file uploaded to the machine, and once set and trialled the machine will continue to turn out parts under the occasional supervision of an operator.\nThe machine is controlled electronically via a computer menu style interface, the program may be modified and displayed at the machine, along with a simulated view of the process.\nThe setter/operator needs a high level of skill to perform the process.\nHowever, the knowledge base is broader compared to the older production machines where intimate knowledge of each machine was considered essential.\nThese machines are often set and operated by the same person, where the operator will supervise a small number of machines (cell).\nThe design of a CNC lathe varies with different manufacturers, but they all have some common elements.\nThe turret holds the tool holders and indexes them as needed, the spindle holds the workpiece and there are slides that let the turret move in multiple axes simultaneously.\nThe machines are often totally enclosed, due in large part to [occupational health and safety](https://bliptext.com/articles/occupational-safety-and-health) (OH&S) issues.\nWith rapid growth in this industry, different CNC lathe manufacturers use different user interfaces which sometimes makes it difficult for operators as they have to be acquainted with them.\nWith the advent of cheap computers, free operating systems such as [Linux](https://bliptext.com/articles/linux), and [open source](https://bliptext.com/articles/open-source) CNC software, the entry price of CNC machines has plummeted.\n# [CNC lathe with milling capabilities | upload.wikimedia.org/wikipedia/commons/0/07/MoriSeikiLathe.jpg]\n# [An example turned vase and view of the tool turret | upload.wikimedia.org/wikipedia/commons/c/c1/MoriSeiki-examples.jpg]\n\n## Swiss-style lathe / Swiss turning center\nA **Swiss-style lathe** is a specific design of lathe providing extreme accuracy (sometimes holding tolerances as small as a few tenths of a thousandth of an inch—a few [micrometers](https://bliptext.com/articles/micrometers)).\nA Swiss-style lathe holds the workpiece with both a [collet](https://bliptext.com/articles/collet) and a guide [bushing](https://bliptext.com/articles/bushing-bearing).\nThe collet sits behind the guide bushing, and the tools sit in front of the guide bushing, holding stationary on the Z axis.\nTo cut lengthwise along the part, the tools will move in and the material itself will move back and forth along the Z axis.\nThis allows all the work to be done on the material near the guide bushing where it is more rigid, making them ideal for working on slender workpieces as the part is held firmly with little chance of deflection or vibration occurring.\nThis style of lathe is commonly used under CNC control.\nMost CNC Swiss-style lathes today use one or two main spindles plus one or two back spindles (secondary spindles).\nThe main spindle is used with the guide bushing for the main machining operations.\nThe secondary spindle is located behind the part, aligned on the Z axis.\nIn simple operation it picks up the part as it is cut off, and accepts it for second operations, then ejects it into a bin, eliminating the need to have an operator manually change each part, as is often the case with standard CNC turning centers.\nThis makes them very efficient, as these machines are capable of fast cycle times, producing simple parts in one cycle (i.e., no need for a second machine to finish the part with second operations), in as little as 10–15 seconds.\nThis makes them ideal for large production runs of small-diameter parts.\n# [A view inside the enclosure of a CNC Swiss-style lathe/screw machine | upload.wikimedia.org/wikipedia/commons/0/08/CNC///Swiss///turn///001.jpg]\n\n### Swiss-style Lathes and Live Tooling\nAs many Swiss lathes incorporate a secondary spindle, or 'sub-spindle', they also incorporate **'live tooling** '.\nLive tools are rotary cutting tools that are powered by a small motor independently of the spindle motor.\nLive tools increase the intricacy of components that can be manufactured by the Swiss lathe.\nFor instance, automatically producing a part with a hole drilled perpendicular to the main axis (the axis of rotation of the spindles) is very economical with live tooling, and similarly uneconomical if done as a secondary operation after machining by the Swiss lathe is complete.\nA 'secondary operation' is a machining operation requiring a partially completed part to be secured in a second machine to complete the manufacturing process.\nGenerally, advanced CAD/CAM software uses live tools in addition to the main spindles so that most parts that can be drawn by a CAD system can actually be manufactured by the machines that the CAD/CAM software support.\n\n## Combination lathe / 3-in-1 machine\nA **combination lathe**, often known as a **3-in-1 machine**, introduces drilling or milling operations into the design of the lathe.\nThese machines have a milling column rising up above the lathe bed, and they utilize the carriage and topslide as the X and Y axes for the milling column.\nThe 3-in-1 name comes from the idea of having a lathe, milling machine, and [drill press](https://bliptext.com/articles/drill-press) all in one affordable machine tool.\nThese are exclusive to the hobbyist and [MRO](https://bliptext.com/articles/maintenance-repair-and-operations) markets, as they inevitably involve compromises in size, features, rigidity, and precision in order to remain affordable.\nNevertheless, they meet the demand of their niche quite well, and are capable of high accuracy given enough time and skill.\nThey may be found in smaller, non-machine-oriented businesses where the occasional small part must be machined, especially where the exacting tolerances of expensive toolroom machines, besides being unaffordable, would be overkill for the application from an engineering perspective.\n\n## Mini-lathe and micro-lathe\nMini-lathes and [micro-lathes](https://bliptext.com/articles/micro-lathe) are miniature versions of a general-purpose center lathe (engine lathe).\nThey typically only handle work of 3 to 7 in diameter (in other words, 1.5 to 3.5 in radius).\nThey are small and affordable lathes for the home workshop or MRO shop.\nThe same advantages and disadvantages apply to these machines as explained earlier regarding [3-in-1 machines](https://bliptext.com/articles/).\nAs found elsewhere in English-language orthography, there is variation in the styling of the prefixes in these machines' names.\nThey are alternately styled as mini lathe, minilathe, and mini-lathe and as micro lathe, microlathe, and micro-lathe''.\n\n## Brake lathe\nA lathe specialized for the task of resurfacing brake [drums](https://bliptext.com/articles/drum-brake) and [discs](https://bliptext.com/articles/disc-brake) in automotive or truck garages.\n\n## Wheel lathe\nWheel lathes are machines used to manufacture and resurface the wheels of railway [rolling stock](https://bliptext.com/articles/rolling-stock).\nWhen wheels become worn or compromised from excessive use, this tool can be used to re-cut and recondition the wheel.\nThere are a number of different wheel lathes available including underfloor variations for resurfacing wheels that are still attached to the rail car, portable types that are easily transported for emergency wheel repairs, and CNC versions which utilize computer-based operating systems to complete the wheel repair.\n# [Beyer, Peacock & Company Electrically Driven Wheel Lathe, 1906 | upload.wikimedia.org/wikipedia/commons/0/09/Beyer///Peacock///Electrically///Driven///Wheel///Lathe%2C///1906.jpg]\n\n## Pit lathe\nA lathe for large diameter, though short work, built over a recess in the floor to admit the lower part of the workpiece thus allowing the toolrest to stand at the turner's waist height.\nAn example is on display at the London Science Museum, Kensington.\n\n## Vertical lathe\nFor even larger diameter and heavier work, such as pressure vessels or marine engines, the lathe is rotated so it takes the form of a turntable on which parts are placed.\nThis orientation is less convenient for the operator, but makes it easier to support large parts.\nIn the largest, the turntable is installed flush with the floor, with the headstock recessed below, to facilitate loading and unloading workpieces.\nBecause operator access is less of an issue for them, CNC vertical turning machines are more popular than manual vertical lathes.\n\n## Oil country lathe\nSpecialised lathes for machining long workpieces such as segments of drill strings.\nOil country lathes are equipped with large-bore hollow spindles, a second chuck on the opposite side of the headstock, and frequently outboard steadies for supporting long workpieces.\n\n# Feed mechanisms\nVarious feed mechanisms exist to feed cutting tools into the work at a controlled rate.\nThe aim of these mechanisms is to automate part of the production process with the end goal of improving productivity.\n\n## Bar feeder\nA bar feeder feeds a single piece of [bar stock](https://bliptext.com/articles/bar-stock) into the cutting machine.\nAs each part is machined, the cutting tool creates a final cut to separate the part from the bar stock, and the feeder continues to feed the bar for the next part, allowing for continual operation of the machine.\nThere are two types of bar feeds used in lathe machining: Hydrodynamic bar feeds, which rest the bar stock in a series of channels whilst clamping down on the top and bottom of the bar, and hydrostatic bar feeds, which hold the bar stock in a feed tube using pressurized oil.\n\n## Bar loader\nA bar loader is a variation on the bar feeder concept in that multiple pieces of bar stock may be fed into a hopper, and the loader feeds each piece as necessary.","revisionCount":0},"hasMore":false,"nextCursor":null}

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