Set square
Encyclopedia
A set square or triangle (American English
) is an object used in engineering and technical drawing
, with the aim of providing a straightedge
at a right angle
or other particular planar angle to a baseline
.
The most simple form of set square is a triangular piece of transparent plastic
(or formerly of polished wood) with the centre removed. More commonly the set square bears the markings of a ruler
and a half circle protractor
. The outer edges are typically bevel
led. These set squares come in two usual forms, both right triangle
s: one with 90-45-45 degree angles, the other with 30-60-90 degree angles. Combining the two forms by placing the hypotenuses together will also yield 15° and 75° angles. They are often purchased in packs with protractor
s and compasses
.
Less commonly found is the adjustable set square. Here, the body of the object is cut in half and rejoined with a hinge
marked with angles. Adjustment to the marked angle will produce any desired angle up to a maximum of 180°.
American English
American English is a set of dialects of the English language used mostly in the United States. Approximately two-thirds of the world's native speakers of English live in the United States....
) is an object used in engineering and technical drawing
Technical drawing
Technical drawing, also known as drafting or draughting, is the act and discipline of composing plans that visually communicate how something functions or has to be constructed.Drafting is the language of industry....
, with the aim of providing a straightedge
Straightedge
A straightedge is a tool with an edge free from curves, or straight, used for transcribing straight lines, or checking the straightness of lines...
at a right angle
Right angle
In geometry and trigonometry, a right angle is an angle that bisects the angle formed by two halves of a straight line. More precisely, if a ray is placed so that its endpoint is on a line and the adjacent angles are equal, then they are right angles...
or other particular planar angle to a baseline
Baseline
A baseline is a line that is a base for measurement or for construction; see datum or point of reference .The word baseline may refer to:...
.
The most simple form of set square is a triangular piece of transparent plastic
Plastic
A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...
(or formerly of polished wood) with the centre removed. More commonly the set square bears the markings of a ruler
Ruler
A ruler, sometimes called a rule or line gauge, is an instrument used in geometry, technical drawing, printing and engineering/building to measure distances and/or to rule straight lines...
and a half circle protractor
Protractor
In geometry, a protractor is a circular or semicircular tool for measuring an angle or a circle. The units of measurement utilized are usually degrees.Some protractors are simple half-discs; these have existed since ancient times...
. The outer edges are typically bevel
Bevel
A beveled edge refers to an edge of a structure that is not perpendicular to the faces of the piece. The words bevel and chamfer overlap in usage; in general usage they are often interchanged, while in technical usage they may sometimes be differentiated as shown in the image at right.-Cutting...
led. These set squares come in two usual forms, both right triangle
Right triangle
A right triangle or right-angled triangle is a triangle in which one angle is a right angle . The relation between the sides and angles of a right triangle is the basis for trigonometry.-Terminology:The side opposite the right angle is called the hypotenuse...
s: one with 90-45-45 degree angles, the other with 30-60-90 degree angles. Combining the two forms by placing the hypotenuses together will also yield 15° and 75° angles. They are often purchased in packs with protractor
Protractor
In geometry, a protractor is a circular or semicircular tool for measuring an angle or a circle. The units of measurement utilized are usually degrees.Some protractors are simple half-discs; these have existed since ancient times...
s and compasses
Compass (drafting)
A compass or pair of compasses is a technical drawing instrument that can be used for inscribing circles or arcs. As dividers, they can also be used as a tool to measure distances, in particular on maps...
.
Less commonly found is the adjustable set square. Here, the body of the object is cut in half and rejoined with a hinge
Hinge
A hinge is a type of bearing that connects two solid objects, typically allowing only a limited angle of rotation between them. Two objects connected by an ideal hinge rotate relative to each other about a fixed axis of rotation. Hinges may be made of flexible material or of moving components...
marked with angles. Adjustment to the marked angle will produce any desired angle up to a maximum of 180°.