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Saw

technology Maturity 11-13 Next article →

A saw is a specialized tool used to cut through various materials. It typically consists of a tough blade, a wire, or a chain. The most important part is the hard, toothed edge. While saws are most often used to cut wood, they can also be used for metal or stone.

Saw blade
Saw blade

To understand how a saw works, you must look at the teeth and the cut they create. A toothed saw works by placing its edge against a material. The user then moves the tool back and forth or continuously forward. This motion uses force to tear through the material. This force can be applied by a person's hand or by machines powered by steam, water, or electricity.

When a saw cuts, it leaves behind a narrow channel called a kerf. The kerf is the width of the cut made by the blade. The width of the kerf is not just the thickness of the blade. It is also determined by the "set" of the teeth. The set is the degree to which the teeth are bent sideways away from the blade. By bending the teeth in alternating directions, the kerf becomes wider than the blade itself. This allows the blade to move through the material without binding, which means getting stuck.

Saw blade
Saw blade

Many factors can change the size of a kerf. It depends on the width of the blade and the set of the teeth. It also depends on how much the blade wobbles during the cut. If a blade is too thin, it may wobble excessively and create a wider kerf than expected. A tool called a saw tooth setter can be used to adjust the set of the teeth. In modern technology, a laser beam can also create a kerf. The width of a laser's kerf depends on the power of the laser and the material being cut.

Saws have a very deep history that stretches back to prehistory. The earliest saws were likely made from serrated stone or bone tools. Humans also used materials like flint, obsidian, sea shells, and shark teeth. In France, tools used to cut wood were found in a cave dating to 90,000–30,000 BCE. In ancient Egypt, copper saws were used as early as 2,686 BC.

Cycladic bronze saw
Cycladic bronze saw
Roman Sawblades
Roman Sawblades

Egyptian saws were originally made of hardened copper. They could cut on both the push and pull strokes. As they evolved, they were made of bronze and later iron. During the Iron Age, people developed frame saws that held thin blades in tension.

As technology improved, the materials used for saws changed. Once humans learned to use iron, it became the preferred material. Some cultures used "case hardening" to make the surface harder and sharper. By 1200 BC, steel was being used. Steel is iron with a moderate amount of carbon. In the mid-18th century, a superior material called "crucible cast" steel was made in Sheffield, England. This steel was highly valued because it was hard, ductile, and springy.

Saw grinding in Sheffield; interior view. Wood engraving. Wellcome V0023646
Saw grinding in Sheffield; interior view. Wood engraving. Wellcome V0023646

By the 1820s, Sheffield was a massive center for production. It contained over 50% of the nation's saw makers. Eventually, the United States industry began to overtake the British industry due to better mechanization and high tariffs on imports.

Different types of saws are designed for specific tasks. For example, a ripsaw has a tooth set similar to a chisel. This design helps it rip or tear material apart. A "flush-cutting saw" is different because it has no set on one side. This allows the user to lay the saw flat against a surface to cut without scratching it. Another historical example is the pit saw. This was a large, two-man ripsaw used in early colonial North America. It could be eight to ten feet long. One person, called the "pit-man," stood in a pit while a "top-man" stood above. They worked together to guide the saw and raise it.

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🖼️ Images & Media (10)
File:Saw blade.svg
Saw blade.svg
File:Roman Sawblades.jpg
Roman Sawblades.jpg
File:Cycladic bronze saw.JPG
Cycladic bronze saw.JPG
File:Saw grinding in Sheffield; interior view. Wood engraving. Wellcome V0023646.jpg
Saw grinding in Sheffield; interior view....
File:Mendel I 039 r.jpg
Mendel I 039 r.jpg
File:Land Army girls sawing larch poles for use as pit props at the Women's Timber Corps training camp at Culford in Suffolk. TR912.jpg
Land Army girls sawing larch poles for...
File:Wood-cutting saw at Maine State Museum in Augusta IMG 1985.JPG
Wood-cutting saw at Maine State Museum in...
File:Kitchen-wood saw, Bangor, ME IMG 2582.JPG
Kitchen-wood saw, Bangor, ME IMG 2582.JPG
File:Sega idraulica Leonardo - Museo scienza e tecnologia Milano.jpg
Sega idraulica Leonardo - Museo scienza e...
File:A man is recording sound effects, 1930s.jpg
A man is recording sound effects, 1930s.jpg
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