What Is a Watchmaker's Lathe?

A watchmaker's lathe is a small tabletop machine that is commonly used for repairing or creating the various parts of a watch. Different companies manufacture these miniature lathes. They come in a number of sizes, but all are designed to work on small objects. The lathes may be hand operated or motor driven. Some are computer controlled.

Sometimes called a mini-lathe, a watchmaker's lathe is one of the integral pieces of watchmaking equipment that a horologist uses. One of the smallest lathes available is referred to as 3.5 x 8. These numbers mean that the machine handles stock up to 3.5 inches in diameter (9 cm) and 8 inches (20 cm) in length. Lathes for watchmaking may be hand powered, motorized, or computer numerical controlled (CNC).

Antique lathes are typically hand powered, requiring manual turning of the spindle. Many hobbyists convert these machines to operate with small motors, similar to the ones commonly found on sewing machines. Manufacturers create motorized lathes with variable speed options. Some lathes use belt movement along a motor pulley that gradually decreases in diameter. Positioning the belt on the smaller diameter increases the rotations per minute (RPMs).

Some motorized watchmaker's lathes can change speed automatically without manually manipulation the belt. Depending on the size and type of motor, RPMs range from 70 to 5,000. A CNC watchmaker's lathe can make precise two and three-dimensional cuts based on preprogrammed and programmable software.

The watchmaker's lathe has a headstock and a tailstock which hold the piece while the lathe is operated. Between these two stations there is a tool rest which allows the horologist to hold the tool stably against the piece being worked. Chucks or collets usually hold the piece in place. Collets are conical with an open end that closes around an object when a nut is tightened. Chucks are open in the center and have inward rotating jaws that close in around an object.

A watchmaker's lathe can be used to drill, cut, and create watch pieces that include gears, screws, or nuts. Using the lathe, horologists can grind and polish metal pieces. Watchmakers may also use drill bits, grinding wheels, and single point, hand-held cutting tools known as gravers. These tools resemble angled knives and are usually constructed from carbide steel, which can cut into or across a piece of metal. Many watchmakers create graving tools designed to perform specific types of cuts.