Some computer numerical control lathe heads feature a variable transmission that allows a computer to change their speed and direction.
A lathe headstock is a gear drive that supplies power and rotation to various parts of the lathe. Internally, the headstock typically contains the following main elements: a motor, a spindle, a gear or belt-driven transmission, and bearings of various sizes. The exterior of the lathe headstock can usually be identified by manual control levers, knobs or buttons. A collar or chuck, used to hold the stock, will extend from the headstock of the lathe and complete the spindle assembly.
A lathe headstock is a geared transmission that supplies power and rotation to various parts of the lathe.
An electric motor will usually be found at the base of the head. This usually supplies rotational power through a belt to the transmission. As the drive rotates, various gears and/or pulleys are automatically or manually adjusted until the desired spindle speed and direction of rotation is achieved.
Older lathes may not have an easily adjustable transmission. With them, it will be necessary to remove the access panels on the headstock of the lathe so that the operator can reach the gears. Once the gears are accessible, they can be reset to the desired spindle speed and direction. Some computer numerical control (CNC) lathe heads may contain a variable transmission and this allows the computer control to change speed and direction up or down as needed. Wood cutting lathes are similar to their metal lathe brethren, but the head of the wood lathe will generally be of lighter construction.
Another style of head is found on a Swiss-style lathe. This Swiss style will have a sliding head designed to feed material from the head to the tool through a guide bushing. The collet on a Swiss lathe sits behind a guide sleeve.
Sometimes a chuck can be mounted on the tool end of the spindle; this allows larger pieces to be rotated. If the material is small in diameter and long, it can be embedded in the hollow spindle and clamped. When most of the stock material is contained in the spindle, the surrounding head provides additional protection for the operator. Some spindles may be tapered so that a center and vise can be used to turn the material.
Traditional motor lathes may also have an additional gear system and lead screw built in and extending through the head. This lead screw provides power to the lathe slide and adds versatility. All lathe heads, regardless of design or style, must be equipped with an emergency stop.