Geometrical instruments – Scriber – Curved line
Patent
1974-10-29
1976-09-07
Haroian, Harry N.
Geometrical instruments
Scriber
Curved line
33107R, 33 80, B43L 1314
Patent
active
039785874
ABSTRACT:
In a drafting system for drawing perspective views and the like, a ruling blade has a reference head extending laterally beyond at least one ruling edge formed with one or more pin-receiving holes arranged in line with the ruling edge adapted to receive a pivot pin removably anchored at a selected point on the drawing surface, typically the vanishing point, for edge pivoting of the ruling blade to draw perspective lines on a sheet from a remote point up to the vanishing point and the like. One form of the ruling blade has a center groove in at least one side and preferably in both sides with opposed inside wall surfaces along its length together with a separate cap-like reference head releasably attached to the blade carrying a locking cam selectively moved into engagement with one of the inside wall surfaces to releasably lock the reference head at any position along the grooved ruling blade. In a unitary ruling blade for shorter lines, the reference head is made integral with the blade. A pair of the grooved ruling blades are releasably connected end to end by a slide-on clamp for making longer lines. Another form of reference head is generally shaped in the form of a T-square head which is used in pairs at opposed positions on a grooved ruling blade or connected blades and each T-square reference head is provided with pin-receiving holes at spaced intervals along its length so that one pin on the board positions the blade horizontally and at a selected vertical distance from the vanishing points for drawing vertical lines using a triangle supported on the ruling blade. When a T-square reference head is locked on one end of the grooved ruling blade in a second position the assembly is suitable for use as a T-square.
REFERENCES:
patent: 1189849 (1916-07-01), McKenney
patent: 1248148 (1917-11-01), Milliken
patent: 2026768 (1936-01-01), Aronson
patent: 2526528 (1950-10-01), Zickler et al.
patent: 2981004 (1961-04-01), Edlund
patent: 3381551 (1968-05-01), Lavering et al.
American Machinist/Metalworking Mfg. 9/30/63 p. 77.
Haroian Harry N.
Lewis, Jr. Ancel W.
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