A lathe () 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. Lathes are used in woodturning, metalworking, metal spinning, thermal spraying, reclamation, and glass-working. Lathes can be used to shape pottery, the best-known such design being the potter's wheel. Most suitably equipped metalworking lathes can be used to produce most solids of revolution, plane surfaces, and screw threads or helices. Ornamental lathes can produce more complex three-dimensional solids. 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 the work about the axis of rotation using a chuck or collet, or attaching it to a faceplate using clamps or dog clutch. Lathes equipped with special lathe milling fixtures can be used to complete milling operations. 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.
History
The lathe is an ancient tool. The earliest evidence of a lathe is a depiction in the tomb of Petosiris, dating back to 4th century BC Egypt. There is also tenuous evidence for a turned artifact 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 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 4th 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 organically during the lead up to the Industrial Revolution, with many inventors contributing. They were critical to the manufacture of mechanical inventions of that period. There are many claims in the literature for the person who invented the precision lathe.
...a professor...notes the competing claims and cautions against the "heroic inventor" treatment of the story. Far better to acknowledge, he says, that precision is a child of many parents, that its advances invariably overlap, that there are a great many indeterminate boundaries between the various disciplines to which the word precision can be attached, and that it was, in its early days, a phenomenon that evolved steadily over three centuries of ever-lessening bewilderment. It is, in other words, a story far less precise than its subject. 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 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, 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 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.
Design The most common design is known as the universal lathe or parallel lathe. Other general designs include the frontal and vertical lathe, and others.
Components
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