Lathe

How it works

The workpiece is held either between two centers or in a chuck or on a face plate at the end of the spindle, and the spindle turns it. The tool is not held by hand; it is clamped in a slide rest or tool post on a carriage that traverses along the bed. In Joshua Rose’s description, the bed (the shears) carries the headstock and tailstock and holds them so that the axes of their spindles stay in line wherever the tailstock is placed, and the duty of the headstock is to carry the live spindle, which is driven by a stepped cone pulley.

In the screw-cutting lathe a lead screw geared to the spindle through change wheels moves the carriage a fixed distance for each turn of the work, so the tool cuts a helix. The Science Museum Group describes Henry Maudslay’s lathe of about 1800 in these terms: a slide rest riding on two parallel triangular bars carries a tool holder with a screw feed and a micrometer dial to set depth of cut, and a leadscrew between the bars, geared to the mandrel by change wheels, moves the slide rest along. Rose adds that a back gear, a second set of gears behind the headstock, reduces spindle speed so that the lathe can drive a heavier cut.

Anatomy

Bed (shears): The base that carries the headstock and tailstock and guides the carriage. Maudslay’s first lathes used two triangular bars as both bed and guideways; his lathe of about 1800 had flat guideways on a separate cast iron bed (Woodbury).
Headstock and live spindle: Carries the spindle that rotates the work, driven by a stepped cone pulley in Rose’s examples.
Back gear: Gearing at the back of the headstock that lowers spindle speed for heavier cuts.
Tailstock: Slides on the bed and carries the dead center that supports the far end of work held between centers.
Carriage and slide rest: The tool holder with a screw feed and a graduated dial for depth of cut. Woodbury identifies the dial on the cross-feed screw of Maudslay’s lathe of about 1797 as an innovation.
Lead screw and change wheels: The screw that drives the carriage at a rate set by the gear train, used for cutting threads.
Chuck or face plate: Holds work that is not mounted between centers.

Variants

Pole lathe: A wooden lathe in which a cord from a springy pole and a foot treadle turns the work alternately toward and away from the turner. The Science Museum Group says pole lathes were in use not later than the thirteenth century.
Rose engine lathe: An ornamental turning lathe that cuts shapes using rosettes of different profiles; the Science Museum Group example is dated c.1740 and has a cross slide rest.
Treadle and foot lathes: Rose’s classification names the foot lathe as one run by the foot, which may also be back-geared, hand-fed or self-acting.
Engine (self-acting) lathe: In Rose’s classification, a lathe with a slide rest actuated automatically to traverse the tool to its cut.
Screw-cutting lathe: A lathe provided with a lead screw by which other screws may be cut.
Chucking lathe: A lathe with a larger face plate than usual and a short bed, for work held by means other than the lathe centers.
Turret or capstan lathe: Carries up to sixteen tools in a rotating turret that indexes automatically; the Science Museum Group example is a Pittler machine of about 1892.
Automatic lathe: Cam-driven machines that turn small parts from bar stock without an operator at the tool; the Science Museum Group’s Loewe machine of about 1890 is based on C. M. Spencer’s automatic lathe of 1873.
CNC lathe: Uses numerical control to translate part dimensions into tool movement; the Science Museum Group dates computer numerical control to the 1950s. See the separate entry.

Specifications

Swing over bed · in or mm: Maudslay’s first screw-cutting lathe of about 1797 had a swing of about 3 inches and a length of about 3 feet (Woodbury); Rose describes back-geared lathes of 20 inches swing.
Lead screw pitch · threads per inch or mm: The lead screw of Maudslay’s lathe of about 1797 was one inch in diameter at 0.25 inch pitch (Woodbury). Modern pitches are set by the change gears.
Spindle speed range · rpm: Set by cone pulley steps and back gear, or by a variable drive; no sourced typical value.

Made to

ANSI B11.6
ISO 23125
EN 12840
ISO 230-1

Safety and care

Safety

The Canadian Centre for Occupational Health and Safety (CCOHS) advises removing entanglement hazards such as loose clothing and jewelry, and tying back and confining long hair.
CCOHS advises against wearing gloves, rings or watches at the lathe.
CCOHS advises securing and clamping the piece being worked, and inspecting chucks for wear or damage because flying pieces can be very dangerous.
CCOHS advises removing the chuck wrench immediately after adjusting the chuck.
CCOHS advises making no adjustments while the machine is operating, not placing hands on work turning in the lathe, and not using calipers or gauges on a moving workpiece.
CCOHS advises against heavy cuts on long slender pieces, because the work could bend and fly out of the lathe.
CCOHS advises using a barrier guard when running the lathe in semi-automatic or automatic mode.

Tips

Set over the tailstock by half the total taper
To turn a taper between centers, move the tailstock off line by one half of the total difference in diameter over the length of the work. Rose gives the rule for a taper stated per foot: multiply the full length in feet by the taper per foot and set the tailstock over half of the result, and the rule holds wherever on the work the taper lies. He measures the set-over at the point of the dead center, not at the tailstock body.1
Use the thread dial to cut threads without reversing
Rose describes lathes fitted with a dial on the lead screw so that threads can be cut without stopping the lathe or reversing the motion of the lead screw.1
Use the back gear for heavy cuts
The back gear reduces the speed of the spindle and, in Rose’s words, enables it to drive a heavier cut. A cone pulley with five steps gave five speeds in single gear and five more in back gear on the lathe he describes.1
Support long work with a follower or steady rest
Rose recommends a follower rest, similar to a steady rest, when work is to be turned from end to end or for a considerable distance, because work that springs away from the tool is turned larger or smaller than intended depending on the tool height and the direction of the spring.1
Keep the tool point at the height of the work center
Rose’s analysis of work sprung by the cut finds that with the tool point at the center of the work the same error results whether the work springs up or down, while a point set above center gives different errors depending on the direction. He also notes that the effect of tool height on the power needed becomes slight once the work exceeds about 6 inches in diameter.1

History

Earliest documented

c.730–690 BCE (oldest certain turned object); third century BCE (earliest representation of a lathe)

Etruscan Italy (turned wooden bowl, Tomb of the Warrior, Corneto); Egypt (relief in the tomb of Petosiris)

Woodbury, surveying the archaeological record, treats a fragment of an Etruscan wooden bowl from the Tomb of the Warrior at Corneto, dated 730–690 BCE and now in the Berlin Antiquarium, as the oldest certain trace of lathe work, showing profiling of the outer surface and hollow turning. He regards a wooden bowl from a Mycenaean pit grave (1100–1400 BCE) as doubtful because it shows no turned grooves. The earliest representation of a lathe he knows is a low relief in the Egyptian tomb of Petosiris, which he dates to the third century BCE, showing two kneeling workers: the turner holds a tool resting on the bed bar and the assistant turns the work with a two-hand cord drive.1

The lathe is among the oldest machines in this archive, and its early history is known from a few scattered points. Woodbury observes that wooden objects rarely survive, that craft work other than in Egypt was seldom illustrated, and that ancient authors mention the lathe only in passing. The oldest certain turned object he cites is an Etruscan bowl of about 700 BCE, and the earliest picture of a lathe is the relief in the tomb of Petosiris. He remarks that the Egyptians had the potter’s wheel and the bow drill by about 2500 BCE yet left no trace of a lathe before the fourth or third century BCE, and that the Egyptian language has no word for turning. On that evidence the two-person cord-driven lathe is attested in Egypt only in the Hellenistic period.

For most of its history the lathe was a wood tool. The Science Museum Group describes the pole lathe as a European development of a Middle Eastern type in which the turner sat on the ground, with the centers raised to suit a standing posture and the hand bow replaced by a spring pole and treadle. The work turns toward the operator and away again, and the turner cuts only while it turns toward him. Theophilus’s text of about 1130 and a thirteenth-century manuscript miniature reproduced by Woodbury show the lathe in ordinary use, and a series of ornamental and instrument-maker lathes followed, among them the rose engine lathe the Science Museum Group dates to about 1740.

The metal-cutting lathe required four things the wood lathe lacked: an iron or steel frame stiff enough to hold precision, a tool carried by a guided slide rather than by the hand, a power drive, and an accurate lead screw. Woodbury’s argument is that these elements existed separately before Maudslay. Polhem had an industrial lathe in 1710, Vaucanson and Senot built lathes with power feed, and Wilkinson’s water-driven lathe with a slide rest came into wide use in American industry. What Woodbury credits to Maudslay is the synthesis: precision flat guideways produced by scraping against standard surface plates, a precise lead screw generated from masters made with an inclined knife, and a lathe built to the proportions of the later industrial machine. The Science Museum Group agrees that his machine tools set new standards of precision and records that his slide rest, previously used almost exclusively for ornamental work, was redesigned as an engineer’s tool.

Precision in the lead screw was the limit on precision in every screw the lathe could make. The Science Museum Group states that before Maudslay screw threads were crudely made by hand, and that his tool using an inclined knife cut its own path in hardwood or soft metal blanks, which then served as temporary lead screws to form permanent ones in harder steel. Woodbury adds that Maudslay tried the known methods of generating an original screw and preferred the inclined knife on cylinders of wood, tin, brass and iron. The lathe thereby became a machine that could reproduce its own most critical part, which is the reason the machine tool trades treat it as the parent of the others.

After 1850 the form diversified by function. Whitworth lathes carried change gears for a range of threads, the Loewe and Spencer designs automated bar-stock work with cams, turret and capstan lathes held up to sixteen tools in an indexing head, and numerical control replaced the operator’s hand at the cranks. The Science Museum Group notes that manual machines required very high levels of operator skill to repeat a workpiece to the same dimensions and that mechanical cam control was inflexible. The manual engine lathe nevertheless continues as the general-purpose machine of the toolroom and small shop, where Rose’s requirement of flexibility, a lathe with change gears, a sliding tailstock and a chuck or face plate, still describes it.

Timeline

c.730–690 BCE
Fragment of an Etruscan turned wooden bowl, Tomb of the Warrior, Corneto: the oldest certain trace of lathe work according to Woodbury.1
third century BCE
Relief in the tomb of Petosiris, Egypt, the earliest representation of a lathe: a two-person lathe with the work driven by a cord pulled by an assistant.1
c.1130
Theophilus Presbyter describes lathes for bell cores, censer cores and pewter vessels, one with a crank drive and a tool rest adjustable in steps; Woodbury takes the text as evidence that the lathe was in common use.1
by the thirteenth century
The pole lathe, with a spring pole and treadle, is in use in Europe according to the Science Museum Group.1
1578
Jacques Besson’s Theatrum Machinarum (Lyon) shows a lathe for cutting screw threads; Woodbury treats it as a step toward the industrial lathe.1
1710
Christopher Polhem’s lathe for cutting iron in Sweden, the earliest industrial-size lathe Woodbury identifies.1
1796–1798
David Wilkinson of Pawtucket builds a water-driven lathe with a slide rest and obtains a patent specification dated 14 December 1798; Woodbury describes the lathe as 1796.1 2
c.1797
Henry Maudslay builds his first screw-cutting lathe, about 3 inches in swing and 3 feet long, with triangular-bar guideways, a graduated cross-feed dial and a one-inch lead screw (Woodbury’s dating).1
c.1800
Maudslay’s screw-cutting lathe on a separate cast iron bed with an independently mounted lead screw; the Science Museum Group dates its original screw-cutting lathe c.1800 and says Maudslay used it to pioneer highly accurate screw threads.1 2
c.1800–1805
Maudslay’s thread-originating tool uses an inclined knife to cut master screws in hardwood or soft metal for use as temporary lead screws.1
c.1812–1820
Maudslay & Co. sell a treadle triangular-bar lathe to amateur mechanics and small workshops, with the slide rest redesigned as an engineer’s tool.1
c.1818
Richard Roberts, who began business in Manchester in 1817, invents the back-geared headstock with the cone pulley running loose on the main spindle, according to Roe, who places the invention within a year or two of 1817.1
1873
C. M. Spencer’s automatic lathe, on which the Science Museum Group says Loewe’s c.1890 machine is based.1
c.1880
Whitworth foot-treadle precision screw-cutting lathe no. 626, with change gears.1
c.1892
Pittler capstan or turret lathe carrying up to 16 tools in an indexing turret.1
1950s
Numerical control begins to change machine tool operation, according to the Science Museum Group’s account of CNC.1

Where the sources disagree

Who invented the slide rest and the screw-cutting lathe?

Maudslay deserves the credit. Roe writes that the slide rest has been and will always be credited to Maudslay because he first designed and built it properly and made it generally useful; the Science Museum Group describes his lathe as the machine with which he pioneered accurate screw threads.1 2
Roe; Science Museum Group
Others are named as inventors of the slide rest. Roe lists Bramah, Bentham and Brunel in England and Sylvanus Brown in America as all said to have invented it, notes that David Wilkinson of Pawtucket was granted a patent in 1798, and observes that the slide rest appears in the French encyclopedia of 1772.1
Roe
All the elements of the industrial lathe were known before Maudslay. Woodbury finds a slide rest of 1791 attributed to Sylvanus Brown, a slide rest of 1794 attributed both to Maudslay and to Bramah, a water-driven lathe with slide rest by Wilkinson by 1796, and a screw-cutting lathe described by Besson in 1578. He credits Maudslay with the synthesis that set the form of the later lathe.1
Woodbury

When did Maudslay build his first screw-cutting lathe?

About 1797 for the first screw-cutting lathe, and about 1800 for a second, both now in the Science Museum.1
Woodbury
c.1800, described as made at the end of the eighteenth century.1
Science Museum Group (object 1900-20)

How early is the lathe in Egypt and the ancient Aegean?

No lathe is attested in Egypt before the Hellenistic period. The first representation is the relief in the tomb of Petosiris, which Woodbury dates to the third century BCE, and the earliest turned Egyptian objects he cites are salve flasks from fourth-century sarcophagi at Abusir and Hellenistic sofas with turned legs. Apparently turned furniture legs of the late New Kingdom prove on examination to be carved and polished.1
Woodbury
The oldest certain turned object is the Etruscan bowl of 730–690 BCE. Whether a Mycenaean bowl of 1100–1400 BCE was turned is uncertain, though Woodbury allows that the first of the mounting methods he discusses may possibly have been used at Mycenae in the twelfth century BCE.1
Woodbury

Gaps in the record (7)

Claims on popular websites that Egyptians used a bow lathe around 1300 BCE, including in the tomb of Tutankhamun, were not found in any archaeological source read for this entry, and Woodbury states that no evidence of a lathe exists in Egypt before the fourth or third century BCE; the claim is not used.
The Petosiris relief is known here through Woodbury’s discussion and his reference to Lefebvre, Le tombeau de Petosiris (Cairo, 1923–24), plate 10, which has not been read; Woodbury gives the tomb a third-century date in one place and refers to the fourth century in another.
Woodbury’s History of the Lathe is the principal secondary source for the pre-1850 narrative; his catalog numbers for Maudslay’s two lathes (M. 3117 and M. 3116) have not been matched to Science Museum object 1900-20.
No patent text for Wilkinson’s 1798 slide rest or for Maudslay’s work has been located.
Lathe spindle-nose and center standards (taper numbers) have not been sourced, and no sourced typical swing or speed values are given.
Care and maintenance guidance (lubrication, way wiping, adjustment of gibs) has not been sourced; care is empty.
Origin of numerical control and of the CNC lathe is left to the CNC lathe entry.