The engine lathe is a lathe machine designed for general purpose lathe work. Its components are the headstock, tailstock, carriage and the bed, a part of the lathe where the headstock and carriage move. An engine lathe's size depends on the size of stock that it can work on. Engine lathes also have variations according to size and features that can be grouped into three categories: bench-type engine lathes, precision tool lathes, and gap or extension-type lathes.
The bench-type engine lathe is a machine that can be mounted on a table and can perform most machining jobs. This kind of lathe is best for places where space is minimal; however, the size of workpieces it can handle is limited. For larger pieces, precision tool lathes or standard manufacturing lathes are used. The precision tool lathe can perform all lathe operations and can handle pieces up to 25 inches (63.5 cm) in diameter and 200 inches (508 cm or 5.8 m) long. For larger and longer pieces, a gap or extension-type lathe is more suitable as it is adjustable to accommodate pieces of larger dimensions.
Turret lathes are used when multiple operations are required on a single workpiece. Instead of an engine lathe tailstock, it has a hexagonal turret or a multiple tool holder and is equipped with a pump and basin for automatic coolant or lubricant application. Users of turret lathes can also switch tools without having to transfer a workpiece to another machine.
Special purpose lathes are machines tailored toward more specific jobs. These machines cannot be used for lathe work outside of their design. Examples of special purpose lathes are the mass-production lathe, the bench-type jeweler's lathe, the automatic screw machine and the brake drum lathe.
The computer numerical control or CNC lathe is any kind of lathe that is fitted with a CNC system for automated work. A CNC system consists of a computer that accepts computer assisted design or CAD data, interprets the data and causes the lathe to machine a workpiece automatically according to CAD specifications. As CAD data can include specifications such as the speed of the motion axes and the spindle, a CNC lathe can produce a variety of cuts such as curved contours without the need for specially shaped tools.
CNC machines have the advantages of consistency and automation, they can operate for an indefinite time continuously, only being switched off for maintenance, they require less training and skill to use, and one person can supervise multiple CNC machines simultaneously. CNC machines, however, have the disadvantage of being expensive to purchase, maintain and repair.