Lathe

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

Lathes are very useful for working with both wood and metal. They can make rounded shapes, flat surfaces, and even 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 different methods, such as 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 even 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, where it shows a person named Petosiris. We also have pieces of turned wood from even older times.

During the Warring States period in China, around 400 BC, people used rotary lathes to shape tools and weapons on a large scale.

Precision metal-cutting lathes grew during the time leading up to the Industrial Revolution. They were very important for making many mechanical inventions. Many people helped develop these better lathes.

By the 1770s, precision lathes became common tools. During this time, a horse-powered lathe was set up in the Royal Arsenal in Woolwich, England, to make stronger and more accurate cannons. 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 known as the universal lathe or parallel lathe. Other general designs include the frontal and vertical lathe.

A lathe may or may not have legs, which sit on the floor and raise the lathe bed to a working height. A lathe can be small and sit on a workbench or table.

Almost all lathes have a bed, which is usually a horizontal beam. At one end of the bed is a headstock. The headstock contains spinning bearings. Rotating inside the bearings is a horizontal axle called the spindle. Spindles are often hollow and have a special shape on the end to hold tools. Spindles are powered by a motor and turn the workpiece.

The counterpoint to the headstock is the tailstock. The tailstock can move along the bed and holds tools or supports the workpiece.

Metalworking lathes have a carriage with a cross-slide. Sitting on top of the cross slide is usually another slide called a compound rest, which holds a cutting tool that removes material from the workpiece.

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

Unless a workpiece fits perfectly 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.

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

Other accessories increase the versatility of a lathe and the range of work it may perform.

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 the capacity of the work they may 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 are larger than jewelers' lathes and can sit on a bench or table are called hobby lathes, and larger versions are called "bench lathes". Even larger lathes for individual part production 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 referred to as 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 around the world. These rules help decide how well a lathe works and what it can do. In the United States, a group called ASME made a special rule book called the B5.57 Standard. This book explains how to test and describe how well computer-run lathes and turning centers work.