WO2004058459A1

WO2004058459A1 - A blade holder for a disk compass

Info

Publication number: WO2004058459A1
Application number: PCT/GB2003/005697
Authority: WO
Inventors: William Harper
Original assignee: William Harper
Priority date: 2002-12-28
Filing date: 2003-12-23
Publication date: 2004-07-15
Also published as: AU2003295164A1; GB0230259D0

Abstract

A blade holder or positioner for use in cutting arcs and other shapes from sheets of card, paper, plastics, or textiles in conjunction with a rotating component (which may be a disk compass) with holes set out at the intersections between an Archimedian spiral and a set of radius lines. The blade holder is fitted with one or more projections to fit into hole(s) in the same radius line as the hole accommodating the blade. As the rotating component turns the blade is constrained to accurately cut an arc enabling the user to assemble a series of such arcs to create a curved shaped aperture in the material or solid shape from the material. The blade holder can be made from plastic by an injection moulding process. The blade may be held in a vertical plane or an inclined plane to make bevelled cuts and may have projections from the underside for different cutting depths.

Description

Title: A Blade Holder for a Disk Compass

Description

Part 1: Technical field

This application relates to a blade holder or positioner forming part of a shape cutting system for use by crafters to cut shapes from card, mount-board, wood veneers, textiles, plastic sheets, and thin metal sheets. The blade-holder is an attachment which fits onto a disk often called a disk compass to hold a blade penetrating holes in the disk at the correct angle and cutting depth to make the desired cut as the disk rotates above the material being cut. The system is useful in making greeting cards, patchwork, quilting, marquetry, papercraft, and modelling and many other home-based crafts.

Part 2: Background Art

There are several 2-dimensional-shape cutting devices available to the craft market but almost all of these devices rely on dies or templates which allow little or no scope for variations in shape or size of the cut aperture or solid shape. A new die or template must be purchased each time a new shape is required and the desired shape may not be available forcing the crafter to compromise on their intended designs at an early stage. These systems are complex and expensive and generally do not allow for bevelled edges.

In addition there exists an instrument sometimes called a disk compass, which is a disk which can rotate around a centre-pin, with numerous holes through the disk arranged along an Archimedian spiral to accommodate the tip of a pencil, pen, or blade. The writing or cutting instrument moves in an arc of a circle as the disk rotates. At the time of writing this is the subject of a GB Patent application - number 0008188.5 "A Shape Cutting System". A body of knowledge now exists to accurately cut a huge variety of shapes like ovals, hearts, spirals, arches, tear drops etc using techniques specifically designed for use with the disk compass. These shapes are essentially formed by geometrical construction and as such can be varied in size and shape but this process is made far easier because of the ease of use and inherent accuracy of the system. The commercial form draws and cuts arcs of radii 1-100mm in increments of 1 mm - almost imperceptible changes in size to many users. Prior to the UK Application forming the prior art to this international application this instrument was used to control scalpels and craft knives which were hand held but there is an element of skill required to hold the blade vertically and at a tangent to the arc being cut and at the required depth of cut. If the blade is not held at a tangent, then the material being cut forces the blade out of its desired circular path resulting in undesirable movement of the disk. If the blade penetration is too great then it digs into the surface beneath the material being cut and the disk tends to rotate around the blade rather than the center-pin. The placing of the hand held knife-blade through the holes is subject to a tolerance of around +/-0.5 mm depending on the design of the holes in the disk and this can result in unsightly joins when the blade is expected to rejoin a previous cut. Use of the correct blade holder instead of a knife ensures the blade is at a tangent to the arc, at the correct cutting depth, and that the radius of turn is more accurate.

Another system currently available employs a hand held knife with a rotating blade inserted through holes in the disk and this blade turns to follow in the path of the hole as the disk turns. This overcomes the tangential problem to some extent but the blade is fragile and not easily replaceable because of its rotating mechanism and it is difficult or impossible to cut tougher or thicker materials like mount-board or wood veneers.

Reference may also be made to patent applications referring to drawing instruments with some design characteristics bearing similarity to the disk compass: WO 89/04770 A1 (Beadle) and US 4129948 (Hatter). Part 3 Disclosure of Invention

The present invention relates to a blade positioner or holder for use in cutting arcs from sheets of card, paper, plastics or textiles in conjunction with a rotating component having a plurality of locating holes which lie at the intersections of lines radiating from the centre of rotation and an Archimedian spiral with the same centre and which accommodate a blade and other fixed projection(s) from the blade-holder in holes in the same radius line so that the blade is always held at a tangent to the arc or circle being cut.

Advantageously the holder may incorporate projections from the blade holder to ensure the desired cutting depth.

The blade positioner or holder may alternatively orient the blade so that the blade produces a bevelled cut during the rotation.

This patent application relates to holders or positioners for use with disk compasses or other rotatable components whose holes lie at the intersections between radial lines and an Archimedian spiral. In this case the distances between any 2 consecutive holes along any particular radius is always the same and this constant distance is used to position the projection^) fixed to the blade- holder. The projection(s) can be adequately shaped and positioned on the holder to exactly fit into a hole in the same row as the blade.

In the simplest embodiment, the blade is secured on the holder in a plane at right angles to the line between the tips of the projection(s) and a corresponding point on the blade. When the holder is placed in position this line is co-incident with the radius of the turn and the blade is at a tangent to the cut so ensuring that there are no undesirable forces produced by the reaction of the cutting material against the sides of the blade causing the blade to follow a non-circular path. By this means the blade can fit into any hole in the disk enabling it to cut arcs of any of the radii relating to the holes. Part 4: Brief Description of Drawings

Fig 1 shows a plan view of the blade holder 101 on a disk compass 102 with holes 103 arranged at the intersection of an Archimedian spiral and a series of 5 radii. Each hole has a different radius of turn and executes a different circle when the disk is turned through 360 degrees. Both the blade 104 and the stud 105 fit into holes in the disk which lie on the same radius line and are always separated by the same distance. The blade 104 is set at right angles to the line between the tip of the blade 104 and the stud 105 and since a projection of this line intersects the axis of rotation 106 of the disk 102, the blade lies in a plane at a tangent to the circle executed by the tip of the blade.

Fig 2 is a vertical section of the blade holder 201 located on a the rotatable component 202 with the blade 204 projecting through one hole 203 in the rotatable component 202 and one stud 205 projecting through another such hole 203.

Part 5: Best mode for Carrying out the Invention

The current model consists of a transparent L-shaped blade-holder injection moulded from a tough polycarbonate plastic. The blade is secured on the vertical face of the holder whilst three studs project from the underside. The blade fits into any hole in the disk and one of the studs fits into another hole in the disk lying on the same radius line as the blade hole. The juxtaposition of the blade and stud ensure that the plane of the blade will then always be tangential to the cylinder being described by the blade as the disk turns.

The other 2 studs lift the blade holder off the surface of the disk and determine the depth of penetration of the blade through the disk. A range of different blade holders is available with differing stud lengths to allow for different penetrations of the blade through the disk and hence different cutting depths for different thicknesses of material being cut.

Part 6: Industrial Applicability

The addition of this blade holder enables the disk compass to be used far more effectively and accurately than when a knife is used to cut the shapes. A wide range of shapes may thus be cut apart from circles. Because of the inherent accuracy of the system, many curved shapes can be approximated by a series of arcs of circles and a booklet is provided with the current model to show how these shapes can easily be achieved. The booklet shows how to cut hearts, ovals, arches, spirals, stars, flowers, etc, covering many of the shapes required in crafts like greeting-card making, marquetry, modeling, patchwork, picture mounting etc

In the commercial version currently in use in the UK the holes in the disk compass allow for circles to be cut at 1 mm increments from 1 to 100 mm radius. The holes are set out along ten radii and the correct hole can easily be located using the disk markings indicating the units digit on each radius line and the tens digit on each lap of the spiral. The spiral increases in radius by 10mm with each lap and the distance between the blade and the locating stud is therefore a multiple of 10mm.

Claims

Claims:

1. A blade positioner or holder for use in cutting arcs from sheets of card, paper, plastics, or textiles in conjunction with a rotating component having a plurality of locating holes which lie at the intersections of lines radiating from the centre of rotation and an Archimedian spiral with the same centre, and which accommodate a blade and other fixed projection(s) from the blade- holder in holes in the same radius line so that the blade is always held at a tangent to the arc or circle being cut.

2. A blade positioner or holder as described in claim 1 where projections from the blade holder are incorporated to ensure the desired cutting depth.

3. A blade positioner or holder as described in claim 1 where the orientation of the blade is such that the blade produces a bevelled cut during the rotation.