Geometrical instruments – Straightedge type
Patent
1984-11-23
1987-06-02
Frankfort, Charles
Geometrical instruments
Straightedge type
33468, 33479, B43L 702
Patent
active
046691979
DESCRIPTION:
BRIEF SUMMARY
This invention relate to drawing aids.
In particular, the present invention is concerned with an arrangement for facilitating the drawing, marking or scribing of continous lines, series of dots or dashes or combinations thereof on a sheet of markable material in such manner that the lines etc., are aligned at a predetermined orientation with respect to a reference direction, such as the edge of the sheet.
In this specification the term markable material is intended to include paper, card, plastics, metal sheet or foil in extended area form and which is of such thickness or characteristic as to be flexible or nonrigid.
It is known to provide aids for drawing lines or series of dots, dashes etc., at a predetermined angle with respect to a reference direction.
One such aid, commonly called a Tee Square, includes a wooden or other rigid material elongate stock defining a reference face or edge along the length thereof and an elongate blade of which at least one of the longer edges thereof is intended to provide a straight edge or guide face for a writing or marking implement, this straight edge or guide face being conventionally perpendicular to the stock reference face or edge.
In use of the known Tee Square it is necessary for the stock reference edge to abut the side or end face of a raised platform such as a drawing board or drafting table upon which the sheet material to be marked has been previously secured in place.
In practice, the sheet of material is conventionally `set` or oriented for the purposes of drawing thereupon by engaging the Tee Square stock with one of the end faces of the board or table and then causing the lower edge of the sheet of paper to abut the Tee Square blade guide edge thereby to ensure that the lower edge of the paper sheet is parallel to the Tee Square blade guide edge. Following this alignment, the paper is firmly secured i.e., pinned or taped to the board or table so as to prevent any subsequent movement. In using the Tee Square the latter is moved up or down whilst maintaining the stock against the board or table with respect to the paper sheet and lines etc., are drawn where required.
Since the Tee Square stock needs to have considerable depth or thickness for the purposes of structural strength and rigidity it is, in practice, necessary positively to secure the sheet material on a platform (i.e., board or table) which provides an accurately rectilinear reference edge of an adequate vertical depth for the effective use of the Tee Square. If this platform is not available it is not possible to use the Tee Square. Consequently, the use of a Tee Square or like drawing aid is wholly restricted to the availability of the support platform with the requisite accuracy in construction for receiving and guiding the The Tee Square stock edge. In other words the known Tee Square constructions cannot be regarded as being suitable as a portable drawing aid.
It is an object of the present invention to provide a drawing aid which avoids the above mentioned difficulties such as the need for a platform type of sheet support with an accurate guide edge.
According to the present invention there is provided a drawing aid incorporating at least one guide edge for co-operation with a material marking means, for facilitating the drawing of lines or other markings upon sheet material lying upon a support surface, characterised in that the drawing aid is adapted to utilise a marginal edge region of a sheet of material in such manner that the sheet edge is caused to provide a reference or direction guide for the drawing aid when operationally setting or positioning the aid with respect to the sheet.
Conveniently the adaptation is such that when the aid is in co-operation with the marginal edge region relative movement between the sheet and the aid and between the sheet and the support surface is simultaneously prevented.
In a preferred construction the aid incorporates an elongate blade portion defining said at least one guide edge and in addition the aid includes a location portion adapted for co-
REFERENCES:
patent: D137749 (1944-04-01), Murphy
patent: 1614812 (1927-01-01), Trane et al.
patent: 1802217 (1929-03-01), Raine
patent: 2046936 (1936-07-01), Castronovo
patent: 2883754 (1959-04-01), Luebkeman
patent: 2923061 (1960-02-01), Dolgorukov
Frankfort Charles
Scanlon Patrick R.
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