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OwnerJonathan Knight, Martin Riddiford +1inventors
InventorsJonathan Knight, Martin Riddiford, Stephen O. Frazer
Estimating the term…
Drawing boards and drawing instruments for use therewith. The surface of the board (1) has a set of parallel-running, evenly spaced magnetic poles (2) across it. Each drawing instrument has a cylinder (10) with similar parallel magnetic poles running essentially axially along it. The cylinder is freely rotatably mounted (12) and preferably held a little bit away from the board surface. The cylinder (10) preferentially orientates with its magnetic poles aligned with those (2) on the board surface. This orientation can be accurately maintained across the entire surface of the board without the use of cumbersome mechanical arrangements to ensure alignment of drawing instruments. When not required for use, the drawing instrument may simply be removed from the surface of the board. A ruler/protractor device (3) and a carriage bearing a pair of rules set at right angles are described.
Drawing apparatus comprising a drawing board having at least one permanently magnetised surface, the magnetisation being in the form of a series of alternating poles extending in parallel straight lines across the board surface, and a draughting device for cooperation therewith, the device including a housing having first and second parts, the first part being freely rotatable relative to the second part about an axis perpendicular to the board surface when the second part is resting on the board surface, and the device further including a magnetic cylindrical member mounted in the first part of the housing so as to rotate freely about the longitudinal axis of the magnetic cylindrical member, the cylindrical member having an arrangement of alternating poles around its cylindrical surface, the spacing of the poles being substantially equal to the spacing of the poles on the board surface, and each pole extending substantially axially along the cylindrical surface of the magnetic cylindrical member.
Dependencies are inferred from the claim text.