GB2266277A

GB2266277A - Drawing stencil.

Info

Publication number: GB2266277A
Application number: GB9208719A
Authority: GB
Inventors: C P Johnson
Original assignee: ECLIPSE DESIGN CONSULTANTS Ltd
Current assignee: ECLIPSE DESIGN CONSULTANTS Ltd
Priority date: 1992-04-21
Filing date: 1992-04-21
Publication date: 1993-10-27
Anticipated expiration: 2012-04-21
Also published as: GB2266277B; GB9208719D0

Abstract

A stencil 10 for drawing objects with rotational symmetry comprises arrays (14) of slots (16) arranged in a regular pattern about a central hole (18). The slots may or may not be rotationally symmetrical about the central hole. The stencil can be used to draw polygons, wheel spokes, cogs and ratchets. <IMAGE>

Description

Title Stencil Field of the invention The present invention relates to a stencil.

Background of the invention Stencils consist of a plate, usually transparent, having holes or slots for guiding the tip of a pencil or a pen to allow shapes to be drawn rapidly by draughtsmen. Known stencils allow drawing of alphanumeric characters in different fonts and point sizes as well as other symbols and geometric shapes commonly found in technical drawings, such as squares, triangles, circles, semi-circles and ellipses.

Object of the invention The present invention seeks to provide a stencil for facilitating the drawing of shapes having rotational symmetry about a point, for example regular polygons and spokes on a wheel.

Summary of the invention According to the present invention, a stencil is provided which comprises at least one array of five or more slots arranged in a regular pattern about a central point.

In one embodiment of the invention, the pattern is rotationally symmetrical.

Preferably, the slots extend radially from the central point.

Conveniently, the stencil comprises a plurality of arrays each having a different number of slots.

Each array on the stencil of the preferred embodiment of the invention permits a circle to be divided into a number of arcs of equal length and by using several arrays on the same stencil one can enable a circle to be divided evenly into different numbers of sectors. The points on the circle may then, for example, be joined to one another to form regular polygons and stars or they may be joined to the centre to form regular radii. The versatility of such patterns will be clear to the experienced draughtsman who will appreciate the ease with which they can be used to draw items such as cogs and ratchets and a multitude of other objects having rotational symmetry.

To assist in drawing the same type of object in perspective view, it is alternatively possible for the slots to be disposed in a regular pattern corresponding to the projection of a rotationally symmetrical pattern onto an inclined plane. The pattern of the slots would in this case, for example, resemble the spokes of a wagon wheel when viewed from one side.

Brief description of the drawing The invention will now be described further, by way of example, with reference to the accompanying drawing which is a plan view of a stencil in accordance with the invention.

Description of the preferred embodiment The stencil 10 of the preferred embodiment of the invention is formed of a sheet of clear plastics material having ruler marking 12 along one edge. To assist in dividing circles into different numbers of equi-angular sectors, the stencils has arrays 14 of slots 16 each consisting of a number of radial slots extending from a central point marked by a small hole 18 for a pencil or compass point. The illustrated stencil has eighteen such arrays ranging from three slots to twenty slots, the number of slots in each pattern being indicated on the stencil in Arabic numerals.

It will be appreciated that this stencil has a certain degree of redundancy in that the patterns with eleven to twenty slots can be used to draw objects with fewer degrees of symmetry. It is possible to form slots of unequal length to enable the same pattern to be used to draw objects having a sub-multiple of the degrees of symmetry of the pattern.

For example, in the pattern with sixteen slots, using compass bearings to identify the individual slots, one can form long slots for those pointing N, E, S and W, shorter slots for those pointing NE, SE, SW and NW and shorter slots still for the remaining slots. In this way, objects with four, eight and sixteen degrees of symmetry can all the drawn using the same pattern.

As can be seen in the drawings, the slots 16 do not reach as far as the centre point 18 but only lie between two circles centred on the point 18. It is thus possible to form two arrays of different outside diameter concentrically one inside the other to make a more compact stencil.

As described, the stencil is intended to assist in drawing plan views of rotationally symmetrical objects. In order to provide similar assistance in drawing such objects when viewed in perspective, it possible to form a stencil on which the arrays of slots conform to the projection of the illustrated patterns onto inclined planes. For the patterns illustrated, the tips of the slots would lie on ellipses and the angular separation of the slots would vary regularly around the perimeter of the ellipse, the slots near the minor axis of the ellipse being furthest apart and those near the major axis of the ellipse being closest together.

Claims

1. A stencil comprising at least one array of five or more slots arranged in a regular pattern about a central point.

2. A stencil as claimed in claim 1, wherein the pattern is rotationally symmetrical.

3. A stencil as claimed in claim 1 or 2, wherein the slots extend radially from the central point.

4. A stencil as claimed in any preceding claim, having a plurality of arrays each having a different number of slots.

5. A stencil as claimed in any preceding claim, wherein the slots in each pattern are of equal length.

6. A stencil constructed substantially as herein described with reference to and as illustrated in the accompanying drawing.

6. A stencil as claimed in claim 1, wherein each pattern consists of the projection of a rotationally symmetrical pattern onto an inclined planed.

7. A stencil constructed substantially as herein described with reference to and as illustrated in the accompanying drawing.

Amendments to the claims have been filed as follows 1. A stencil comprising a plurality of arrays each having a number of slots arranged in a regular pattern about a hole in the stencil located at the axis of symmetry of the pattern, at least one of the arrays having five or more slots.

3. A stencil as claimed in claim 1 or 2, wherein the slots extend radially from the hole at the axis of symmetry.

4. A stencil as claimed in any preceding claim, wherein the slots in each pattern are of equal length.

5. A stencil as claimed in claim 1, wherein each pattern consists of the projection of a rotationally symmetrical pattern onto an inclined planed.