Drafting apparatus

Abstract

 A drafting apparatus (10) comprises a frame (12) on which is mounted rollers (14) made up of two elongate cylinders. The rollers (14) are connected to each other by a polymeric band (24). In use of the invention a drafting instrument such as a rule is mounted on the apparatus (10) which may be pushed on a drafting surface.

Description

[0001] This invention relates to a drafting apparatus and in particular to an apparatus having rollers for moving on a drafting surface.

[0002] Drafting instruments having single rollers with or without traction bands are known in the prior art. In United States Patent 3,745,657 (Gonzalez) an instrument for drawing parallel lines is described as having a roller formed from a rubber-like material. Drafting instruments having rollers are also described in United States Patents 3,473,228 (Hortmann et al), 1,051,712 (Eager), 1,005,218 (Holmes) and 3,266 157 (de Mathe), United Kingdom Patents 1.5,324 (Hilton) and 355,483 (Hahn) and Austrian Patent 40811.

[0003] It is an object of the invention to provide a drafting apparatus having rollers.

[0004] According to the invention there is provided a drafting apparatus including a frame having means for receiving one or more drafting instruments, at least two elongate rollers mounted in tandem and in a spaced apart relationship across the width of the frame and an endless polymeric band extending over the rollers and engaging the outer periphery of the rollers so that the rollers can rotate in unison.

[0005] In a preferred form of the invention the rollers comprise two in number and may be connected to each other by an idler wheel disposed between the rollers for rotating them in unison. Preferably the idler roller is mounted between the two rollers and arranged to bear on the outer surface of the polymeric band and thereby tension the band.

[0006] The band preferably contacts the peripheral surface of the rollers and engagement of the track is by friction. Alternatively the outer peripheries of the rollers may be toothed for meshing with a toothed inner surface of the band. The band may be in the form of a single narrow endless band located on the rollers or more than one band located in a spaced apart relationship from each other. The rollers in addition preferably include bands fixed individually around their peripheral circumference.

[0007] Preferably the frame includes an edge which is adapted to form a rule or other drafting aid. The frame preferably includes a device having one or more slots adapted for removably receiving drafting aids. Preferably the device is in the form of an "S" with the slots disposed in opposite directions. The walls of the slots are preferably resilient for frictionally engaging a drafting instrument.

[0008] Embodiments of the invention are descrlbed by way of examples with reference to the accompanying drawings in which:

Figure 1 is a perspective view of one embodiment of a drafting apparatus according to the invention;

Figure 2 is a side view of another embodiment of a drafting apparatus; and

Figure 3 is a side view of an attachment device.

[0009] Referring to the drawings a drafting instrument 10 has a frame 12 on which is mounted two rollers 14.

[0010] The frame 12 is an elongate substantially triangular in section body having an open base from which projects the rollers 14. A finger seating formation 16 is formed as a depression in the frame 12 and at is midpoint. At the forward edge of the frame 12 a rule 18, gradated in the conventional manner, is fixed.

[0011] The rollers 14 comprise two elongate cylinders mounted to rotate on axles 20. The length of the rollers is slightly less than the length of the housing so that a part of the rollers can be accommodated within the frame 12. Rubber bands 22 are fixed at the ends of the rollers 14. A polymeric band 24 is fitted over the rollers 20 and in the area between the rubber bands 22. The thickness of the polymeric band 24 is less than the thickness of the rubber bands 22. The polymeric band 24 is stretched over the rollers 14 and is hence is frictional sliding relationship over the edges. The axles 20 of the rollers 14 are mounted on the frame 12 by means of a side cover 26. In an alternative embodiment the rollers 14 may be connected through a suspension mechanism for rocking movement of the frame 12 independently of the rollers 14.

[0012] In the embodiment seen in Figure 2 two cylindrical rollers 28 are connected to each other by a broad band 30 which is frictionally located over both rollers. In this embodiment the band 30 extends as two narrow zones at the ends of the rollers 28 and increases the surface area of contact of the band 30 with a surface.

[0013] The attachment device 32 seen in Figure 3 is removably fixed to the frame of a drafting instrument by the resilience of its U shaped legs 34. A rule or other drafting instrument can be attached to a drafting instrument by location between the legs 34,36.

[0014] In use of the invention the drafting apparatus 10 may be used for drawing lines or performing other drafting functions. By use of the attachment device 32 any instrument such as a protractor, rule, set square, cursor or the like may be attached for use. The bands 22 are formed from a non-slip material and this together with the greater surface area of contact of the band 30 make the drafting apparatus very accurate and versatile. When for example a line has to be ruled, the apparatus 10 is tilted forwardly until the edge of the rule 18 rests on the paper. In this position only the forward roller contacts the surface of the paper.

[0015] The features disclosed in the foregoing description, in the following claims and/or in the accompanvinn drawings may, both separately and in anv combination thereof, be material for realising the invention in diverse forms thereof.

Claims

1. A drafting apparatus characterised in including a frame having means for receiving a drafting instrument, at least two elongate rollers mounted in tandem and in a spaced apart relationship across the width of the frame, and a endless polymeric band extending over the rollers and engaging the outer periphery of the rollers so that the rollers can rotate in unison.

2. A drafting apparatus according to claim 1 characterised in that each roller includes a band fixed over at least a part of its circumference.

3. A drafting apparatus according to claim 1 or claim 2 characterised in including a clip for removably receiving a drafting instrument.

Drawing