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(design engineering)
A strip of wood, plastic, or metal with one or more long edges made straight with a desired degree of accuracy.



in machine building, a rule for testing the flatness and parallelism of a surface. Straightedges measure the maximum distance between points on the surface’s profile and a contiguous straight line—the edge of the rule.

Two types of straightedges are distinguished: toolmakers’ straightedges (master straightedges) and straightedges with a broad working surface. The master straightedges may have two edges, three faces, or four faces. Other straightedges have a broad working surface with a right angular or bow shape or I-beam cross section. Master straightedges are used to test the flatness and parallelism of a surface by means of the gap between the surface and the edge of the straightedge applied to it. It is thus possible to detect gaps of 1–5 microns (μ). Straightedges with broad working surfaces determine flatness and parallelism by measuring linear deviations of the surface being inspected in comparison with the surface of the straightedge, which is held on supports. Checking for flatness may also be done by painting the surface to be inspected and moving the straightedge across it; the paint will then be scraped off the raised portions of the surface. Angled straightedges are used only with this method.

Master straightedges are made in various lengths from 80 to 500 mm. Straightedges with broad working surfaces have lengths of 200 to 4,000 mm, and angled straightedges have lengths of 630 to 1,000 mm, with angles of 45°, 55°, and 60°. The working surfaces of master straightedges deviate from linearity by 0.6 to 4 μ, depending on the length and the degree of accuracy. The variation of flatness in straightedges with broad working surfaces depart from flatness by 2.5 to 100 μ.


straightedge, rod

1. A rigid, straight piece of wood or metal used to strike off a concrete, mortared, or plastered surface; a screed, 2.
2. A long piece of seasoned, planed wood having straight, parallel edges; used in construction to lay out straight lines and to align framing.
References in periodicals archive ?
As will be seen, the construction of tangents using this method is simple even in comparison to the construction of tangents using a straightedge and a compass.
Gauss proved that an n-sided regular polygon can be constructed by compass and straightedge if and only if n is equal to a power of 2, and, possibly, multiplied by distinct Fermat primes.
Using an engineer's scale instrument to measure and a triangle as a straightedge, draw a line 30 feet long to the scale of 1" = 10'.
It states: "While defininitely not a body modification term, many people involved in body modification consider themselves to be straightedge.
Use the straightedge to help you cut along a straight line.
8-m straightedge placed across the wheelpath and the surface of the pavement, and the width of the rut based on a 1.
He showed that only polygons of certain numbers of sides could be constructed with compass and straightedge alone.
The Russian Constructivist Aleksandr Rodchenko, for example, programmatically empoyed geometric forms generated by such instruments as compass and straightedge specifically to obliterate personality.
Before you begin tiling, check the surface with a straightedge.
Although I'm 44 years old now, no longer youthful or straightedge, I still hold those times in high regard and it was a real highlight of my life.
Contract awarded for purchase of fractional set, set straightedge numerical, and technical drawing set set for school geoboards azolas juan madrid e-255-plan fund improvement-sep