Lathe

A lathe is a special machine tool that spins a piece of material around a center point. This helps workers shape the material in many ways, such as cutting, sanding, drilling, and turning. The tools used for shaping move close to the spinning material to make smooth, symmetrical objects.

Lathes are very useful for working with both wood and metal. They can make rounded shapes, flat surfaces, and twisty parts like screws. People use lathes to create many everyday items, including screws, candlesticks, table legs, bowls, and baseball bats. The material being shaped is held in place using clamps or special holders called chucks.

Because of their flexibility, lathes are important tools in many kinds of work, from making musical instruments to crafting pottery on a potter's wheel. With the right setup, a lathe can help make detailed and beautiful three-dimensional shapes for decoration.

History

The lathe is a very old tool. The earliest picture of a lathe comes from a tomb in ancient Egypt from the 4th century BC.

During the Warring States period in China, people used rotary lathes to shape tools and weapons.

Precision metal-cutting lathes grew during the time leading up to the Industrial Revolution. They were important for making mechanical inventions.

By the 1770s, precision lathes became common tools. Later, during the Industrial Revolution, machines powered by water or steam engines made lathes faster and easier to use. Over time, electric motors and computer controls improved lathes even more.

Design

The most common design is called the universal lathe. Other designs include the frontal and vertical lathe.

A lathe may or may not have legs. Legs raise the lathe to a working height. A lathe can be small and sit on a table.

Most lathes have a bed, which is a horizontal beam. At one end is a headstock. The headstock has spinning bearings. Inside the bearings is a horizontal axle called the spindle. The spindle is powered by a motor and turns the workpiece.

The tailstock is the opposite of the headstock. The tailstock moves along the bed and holds tools or supports the workpiece.

Metalworking lathes have a carriage with a cross-slide. On top of the cross-slide is usually a compound rest. The compound rest holds a cutting tool that removes material from the workpiece.

Woodturning and metal spinning lathes do not have cross-slides. Instead, they have banjos. Banjos are flat pieces that sit across the bed.

Unless a workpiece fits into the spindle, an accessory must be used to mount it. A workpiece may be bolted to a faceplate, or held in a mandrel, or clamped in a three- or four-jaw chuck. For precision work, cylindrical workpieces are usually held in a collet.

A soft workpiece may be pinched between centers using a spur drive at the headstock.

An "index plate" is a circular metal plate with evenly spaced holes. It is mounted to the spindle. It can be used to rotate the spindle to a precise angle and lock it in place.

Other accessories make a lathe more versatile and allow it to do more kinds of work.

When a workpiece is fixed between the headstock and the tailstock, it is said to be "between centers". When a workpiece is fixed only to the spindle at the headstock end, the work is said to be "face work".

Lathes are usually 'sized' by how much work they can hold. The distance between centers gives the maximum length of work the lathe will hold.

The smallest lathes are "jewelers lathes" or "watchmaker lathes". Smaller metalworking lathes that can sit on a table are called hobby lathes. Larger versions are called "bench lathes". Even larger lathes for making parts are called "engine lathes".

Lathes with a very large spindle bore and a chuck on both ends of the spindle are called "oil field lathes".

Fully automatic mechanical lathes are called screw machines.

Lathes that are controlled by a computer are CNC lathes.

Lathes with the spindle mounted vertically are called vertical lathes or vertical boring machines.

A lathe with a tool post that can rotate around a vertical axis is a turret lathe.

A lathe equipped with special tools for ornamental turning is an ornamental lathe.

Lathes can be combined with other machine tools, such as a drill press or vertical milling machine. These are usually called combination lathes.

Uses

Woodworking

Woodworking lathes are the oldest type of lathe. They have a metal rail called the tool-rest between the wood and the person using the lathe. Tools are held by hand to shape the wood. After shaping, sandpaper is used to smooth the surface. The tool-rest is often removed during sanding to keep hands safe.

Many woodworking lathes can also shape bowls and plates by holding the piece at the bottom. The piece is usually attached to a metal plate on the lathe’s spinning part.

Duplicating

One special type of lathe is the copying lathe. It can make shapes that match a standard pattern. This type of lathe changed how guns were made in the 1820s when it was invented.

Patternmaking

Lathes are used to make patterns for factories. These patterns are often made from wood but can also be made from plastics. The lathe for this work looks like a heavy wood lathe and has tools to cut straight lines very accurately.

Metalworking

In metalworking, a lathe removes metal from a piece using a hard cutting tool. The tool is moved against the metal using handles or computers. Cutting tools come in many shapes and sizes for different jobs.

The tool can be moved very accurately using screws. Some lathes can cut threads, and others can be controlled by computers for making many parts quickly.

Cue lathes

Cue lathes are used to shape and refinish billiard cues, making sure they are perfectly symmetrical.

Glass-working

Glass-working lathes spin a hollow glass piece over a flame. The flame makes the glass soft so it can be shaped by blowing or using tools. These lathes often have two spinning parts to hold the glass.

Metal-spinning

In metal spinning, a piece of metal is spun while tools press against it to shape it. This is done using a wooden shape called a mandrel. Metal spinning is less common now but is still useful for making small numbers of special pieces.

Ornamental turning

Ornamental turning lathes make decorative objects. They can create very complex shapes using special tools and parts. These lathes are often used for fancy work like decorating watch cases.

Reducing

Some lathes can make copies of an object smaller than the original. These are called reduction lathes. They are used in making coins by copying a plaster or metal original.

Rotary lathes

Rotary lathes are used to turn wood logs into thin sheets called veneer. This veneer is used for making plywood and for covering surfaces.

Watchmaking

Watchmakers use very precise lathes to shape tiny parts for watches. These lathes are delicate and often used with handheld tools.

Transcription or recording

Recording lathes are used to cut grooves into surfaces to record sound. They were first used to make wax cylinders and later for making records. These lathes were driven by sound or electricity.

Performance

Lathes are made and checked using different rules in many places. These rules help decide how well a lathe works and what it can do. In the United States, a group called ASME made a rule book called the B5.57 Standard. This book explains how to test and describe how well computer-run lathes work.