Serration

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The serrated edges of tiger shark teeth Tiger shark serration.jpg
The serrated edges of tiger shark teeth
A hunting knife with a serrated back edge Knife (3263343357).png
A hunting knife with a serrated back edge
Serrated leaves of the stinging nettle, Urtica dioica Ortie.jpg
Serrated leaves of the stinging nettle, Urtica dioica

Serration is a saw-like appearance or a row of sharp or tooth-like projections. A serrated cutting edge has many small points of contact with the material being cut. By having less contact area than a smooth blade or other edge, the applied pressure at each point of contact is greater and the points of contact are at a sharper angle to the material being cut. This causes a cutting action that involves many small splits in the surface of the material being cut, which cumulatively serve to cut the material along the line of the blade. [1]

In nature, serration is commonly seen in the cutting edge on the teeth of some species, usually sharks. However, it also appears on non-cutting surfaces, for example in botany where a toothed leaf margin or other plant part, such as the edge of a carnation petal, is described as being serrated. A serrated leaf edge may reduce the force of wind and other natural elements. [2] Probably[ clarification needed ] the largest serrations on Earth occur on the skylines of mountains (the Spanish word sierra, as in Sierra Nevada, means a saw). These occur both due to the uneven action of landform edges pushing rock upwards, and the uneven action of erosion.[ citation needed ]

Human uses of serration have copied, and gone beyond, those found in nature. For example, the teeth on a saw or other serrated blade serves a similar cutting or scraping purpose as the serration of an animal tooth. Tailors use pinking shears to cut cloth with a serrated edge, which, somewhat counterintuitively, reduces fraying by reducing the average length of a thread that may be pulled from the edge. [3] A type of serration is also found in airframe shapes used in certain stealth aircraft, which use the jaggedness of the serrated edge to deflect radar signals from seams and edges where a straight, non-serrated edge would reflect radar signals back to the source. Screw threads show serration in profile, although they are usually shown in abbreviated or symbolic fashion on mechanical drawings to save time and ink. Brogue shoes are made with serrated edges on the leather pieces, for no known purpose at all other than style. The step clamp and step block assembly in metalworking adopt serration for the purpose of applying clamping pressure from an adjustable position.

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A circular saw is a power-saw using a toothed or abrasive disc or blade to cut different materials using a rotary motion spinning around an arbor. A hole saw and ring saw also use a rotary motion but are different from a circular saw. Circular saws may also be loosely used for the blade itself. Circular saws were invented in the late 18th century and were in common use in sawmills in the United States by the middle of the 19th century.

<span class="mw-page-title-main">Hand saw</span> Wood cutting tool

In woodworking and carpentry, hand saws, also known as "panel saws", are used to cut pieces of wood into different shapes. This is usually done in order to join the pieces together and carve a wooden object. They usually operate by having a series of sharp points of some substance that is harder than the wood being cut. The hand saw is a bit like a tenon saw, but with one flat, sharp edge.

A saw is a tool consisting of a tough blade, wire, or chain with a hard toothed edge. It is used to cut through material, very often wood, though sometimes metal or stone. The cut is made by placing the toothed edge against the material and moving it back and forth, or continuously forward. This force may be applied by hand, or powered by steam, water, electricity or other power source. An abrasive saw has a powered circular blade designed to cut through metal or ceramic.

<span class="mw-page-title-main">Blade</span> Sharp cutting part of a weapon or tool

A blade is the portion of a tool, weapon, or machine with an edge that is designed to puncture, chop, slice or scrape surfaces or materials. Blades are typically made from materials that are harder than those they are to be used on. Historically, humans have made blades from flaking stones such as flint or obsidian, and from various metal such as copper, bronze and iron. Modern blades are often made of steel or ceramic. Blades are one of humanity's oldest tools, and continue to be used for combat, food preparation, and other purposes.

<span class="mw-page-title-main">Hobbing</span> Process used to cut teeth into gears

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<span class="mw-page-title-main">Sickle</span> Single-handed agricultural tool

A sickle, bagging hook, reaping-hook or grasshook is a single-handed agricultural tool designed with variously curved blades and typically used for harvesting, or reaping, grain crops or cutting succulent forage chiefly for feeding livestock, either freshly cut or dried as hay. Falx was a synonym but was later used to mean any of a number of tools that had a curved blade that was sharp on the inside edge such as a scythe.

<span class="mw-page-title-main">Bandsaw</span> Power saw with a long, sharp blade

A bandsaw is a power saw with a long, sharp blade consisting of a continuous band of toothed metal stretched between two or more wheels to cut material. They are used principally in woodworking, metalworking, and lumbering, but may cut a variety of materials. Advantages include uniform cutting action as a result of an evenly distributed tooth load, and the ability to cut irregular or curved shapes like a jigsaw. The minimum radius of a curve is determined by the width of the band and its kerf. Most bandsaws have two wheels rotating in the same plane, one of which is powered, although some may have three or four to distribute the load. The blade itself can come in a variety of sizes and tooth pitches, which enables the machine to be highly versatile and able to cut a wide variety of materials including wood, metal and plastic.

<span class="mw-page-title-main">Bread knife</span> Serrated knife used for cutting bread

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<span class="mw-page-title-main">Miter saw</span> Mechanical saw used to obtain precise angle cuts

A miter saw or mitre saw is a saw used to make accurate crosscuts and miters in a workpiece by positioning a mounted blade onto a board. A miter saw in its earliest form was composed of a back saw in a miter box, but in modern implementation consists of a powered circular saw that can be positioned at a variety of angles and lowered onto a board positioned against a backstop called the fence.

<span class="mw-page-title-main">Kitchen knife</span> Knives intended for use in the process of preparing food

A kitchen knife is any knife that is intended to be used in food preparation. While much of this work can be accomplished with a few general-purpose knives – notably a large chef's knife, a tough cleaver, a small paring knife and some sort of serrated blade – there are also many specialized knives that are designed for specific tasks. Kitchen knives can be made from several different materials.

<span class="mw-page-title-main">Japanese carpentry</span> Distinctive woodworking style

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<span class="mw-page-title-main">Survival knife</span> Knife designed for wilderness survival use

Survival knives are knives intended for survival purposes in a wilderness environment, often in an emergency when the user has lost most of their main equipment. Most military aviation units issue some kind of survival knife to their pilots in case their aircraft are shot down behind enemy lines and the crew needs tools to facilitate their survival, escape, and rescue. Survival knives can be used for trapping, skinning, wood cutting, wood carving, and other uses. Hunters, hikers, and outdoor sport enthusiasts use survival knives. Some survival knives are heavy-bladed and thick. Other survival knives are lightweight or fold in order to save weight and bulk as part of a larger survival kit. Their functions often include serving as a hunting knife. Features, such as hollow handles, that could be used as storage space for matches or similar small items, began gaining popularity in the 1980s. Custom or semi-custom makers such as Americans Jimmy Lile, Bo Randall, and Chris Reeve are often credited with inventing those features.

Milling cutters are cutting tools typically used in milling machines or machining centres to perform milling operations. They remove material by their movement within the machine or directly from the cutter's shape.

<span class="mw-page-title-main">Scroll saw</span> Small electric or pedal-operated saw

A scroll saw is a small electric or pedal-operated saw used to cut intricate curves in wood, metal, or other materials. The fineness of its blade allows it to cut more delicately than a power jigsaw, and more easily than a hand coping saw or fretsaw. Like those tools, it is capable of creating curves with edges, by pivoting its table.

A serrated blade is one with a toothlike rather than a plain edge, and is used on saws and on some knives and scissors. It is also known as a dentated, sawtooth, or toothed blade. Most such blades are scalloped, having edges cut with curved notches, common on wood saws and bread knives.

<span class="mw-page-title-main">Fretsaw</span> Bow saw for intricate cutting

The fretsaw is a bow saw used for intricate cutting work which often incorporates tight curves. Although the coping saw is often used for similar work, the fretsaw is capable of much tighter radii and more delicate work. It has a distinctive appearance due to the depth of its frame, which together with the relatively short five-inch (13 cm) blade makes this tool appear somewhat out of proportion compared with most other saws.

This glossary of woodworking lists a number of specialized terms and concepts used in woodworking, carpentry, and related disciplines.

<span class="mw-page-title-main">Cold saw</span>

A cold saw is a circular saw designed to cut metal which uses a toothed blade to transfer the heat generated by cutting to the chips created by the saw blade, allowing both the blade and material being cut to remain cool. This is in contrast to an abrasive saw, which abrades the metal and generates a great deal of heat absorbed by the material being cut and saw blade.

<span class="mw-page-title-main">Jigsaw (tool)</span> Type of saw

A jigsaw is a saw which uses a reciprocating blade to cut irregular curves, such as stenciled designs, in wood, metal, or other materials.

References

  1. Alloway, David (2000). Desert Survival Skills. University of Texas Press. p. 38. ISBN   978-0-292-70492-3.
  2. Hemsley, Alan R.; Poole, Imogen (2005). The Evolution of Plant Physiology. p. 220.
  3. Audin, Heather (2015). "2". Making Victorian Costumes for Women.