A straightedge is a tool with an accurately straight edge used for drawing or cutting straight lines, or checking the straightness of lines. If it has equally spaced markings along its length it is usually called a ruler.

True straightness can in some cases be checked by using a laser line level as an optical straightedge: it can illuminate an accurately straight line on a flat surface such as the edge of a plank or shelf.

It is possible to do all compass and straightedge constructions without the straightedge. That is, it is possible, using only a compass, to find the intersection of two lines given two points on each, and to find the tangent points to circles. It is not, however, possible to do all constructions using only a straightedge. It "is" possible to do them with straightedge alone given one circle and its center.


* Wayne R. Moore, "Foundations of Mechanical Accuracy", Moore Special Tool Company, Bridgeport, CT (1970)

External links

* [ Making Accurate Straight-Edges from Scratch]

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Look at other dictionaries:

  • Straightedge — Straight edge , n. A board, or piece of wood or metal, having one edge perfectly straight, used to ascertain whether a line is straight or a surface even, and for drawing straight lines. [1913 Webster] …   The Collaborative International Dictionary of English

  • straightedge — [strāt′ej΄] n. a piece or strip of wood, etc. having a perfectly straight edge used in drawing straight lines, testing plane surfaces, etc …   English World dictionary

  • straightedge — noun Date: 1795 a bar or piece of material (as of wood, metal, or plastic) with a straight edge for testing straight lines and surfaces or for cutting along or drawing straight lines …   New Collegiate Dictionary

  • straightedge — /strayt ej /, n. a bar or strip of wood, plastic, or metal having at least one long edge of sufficiently reliable straightness for use in drawing or testing straight lines, plane surfaces, etc. [1805 15; STRAIGHT + EDGE] * * * …   Universalium

  • straightedge — 1. adjective Living ones life against/without the use of alcohol, smoking, and illegal drugs. 2. noun A tool which is flat, rectangular and commonly made of wood, metal or plastic and is used to draw …   Wiktionary

  • straightedge — n. piece of wood or metal with one perfectly straight edge for measuring straightness of other objects or lines …   English contemporary dictionary

  • straightedge — straight•edge [[t]ˈstreɪtˌɛdʒ[/t]] n. bui a bar or strip of wood, plastic, or metal having at least one long edge for use in drawing or testing straight lines, plane surfaces, etc • Etymology: 1805–15 …   From formal English to slang

  • straightedge — /ˈstreɪtɛdʒ/ (say straytej) noun a bar or strip of wood or metal, of various sizes, having at least one edge of sufficiently reliable straightness, for use in obtaining or testing straight lines, plane surfaces, etc …   Australian-English dictionary

  • straightedge — A rule type tool without graduation for checking, e.g., warp of cylinder block and head …   Dictionary of automotive terms

  • straightedge — noun hand tool consisting of a flat rigid rectangular bar (metal or wood) that can be used to draw straight lines (or test their straightness) • Hypernyms: ↑hand tool …   Useful english dictionary

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