Straightedge


Also found in: Dictionary, Thesaurus, Medical, Legal, Financial, Acronyms, Wikipedia.

straightedge

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

Straightedge

 

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.

N. N. MARKOV

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 ?
The straightedge movement began as a faction of the Washington DC punk culture in the late 1970s, and is characterized by an often militant opposition to drug and alcohol use, smoking, promiscuous sex, and the consumption and abuse of animals.
Constructing authentic identities and subcultural boundaries in a straightedge Internet forum.
Using a straightedge and spirit level to check that the whole area is level is also advised.
After this, it wouldn't have surprised me if Weaver took out a straightedge and sliced off Stanley's ear to the tune of ``Stuck in the Middle With You.
The data were collected by three processes: (1) Dipstick[R], (2) a photographic method, and (3) a straightedge used to collect rut depths.
straightedge reversal using aa indicator, require uncertainty statements since the uncertainty of the iadicator must be assessed.
It is wonderfully satisfying to make these pictures by hand, patiently, with pencil and paper, compass and straightedge," Goodman-Strauss adds.
Since it is Angela's turn to respond, she takes a book, holds it upright with one hand and holds another book, a mystery novel, sideways, using it as a straightedge to underscore the title word she wishes to emphasize: Bourreau, which literally means executioner yet also connotes an unfeeling brute.
The company's original product line included drafting tables and drawing boards, office tables, large-format filing cabinets and straightedge parallel-rule systems.
Using a straightedge and an alcohol pen or pencil, he draws out the complete route.
Clamp a straightedge on the door to guide your saw to make this cut.
Three- to four-foot-long board or straightedge (to level the edges or diagonals)