GB2255521A

GB2255521A - Chisel provided with wheels

Info

Publication number: GB2255521A
Application number: GB9110064A
Authority: GB
Inventors: Jurg Gottfried Staubli
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-05-09
Filing date: 1991-05-09
Publication date: 1992-11-11
Anticipated expiration: 2011-05-09
Also published as: GB9110064D0; GB2255521B

Abstract

A wheeled chisel comprises a body (1), a working tip (6) extending from the body, and wheels (5) mounted on the body to enable the body to be supported in a predetermined orientation on a grooved surface with the working tip extending to a predetermined depth into a groove defined by adjacent bricks making up the surface. Blows may be applied to a shaft (2) to drive the body on the wheels in a predetermined direction. The working tip defines a leading edge (8) which extends into the groove either perpendicular to the surface or rearwardly relative to the predetermined direction in which the chisel is driven when blows are applied to the shaft. As there is no sharp point on the working tip of the chisel, the risk of hard mortar being eve red out of the groove and carrying with it the edges of adjacent bricks is effectively removed. <IMAGE>

Description

CHISEL The present invention relates to a chisel, and in particular to a wheeled chisel which can be used to cut material out of a groove formed in a generally flat surface.

British Patent Specification No. GB-A-2207380 describes a wheeled chisel which is particularly useful for removing mortar from grooves defined between adjacent courses of bricks in a wall. The described chisel comprises a body, a working tip extending from the body, wheels mounted on the body to enable the body to be supported in a predetermined orientation on a grooved surface with the working tip extending to a predetermined depth into a groove in the surface, and a shaft to which blows may be applied to drive the body on the wheels in a predetermined direction. The working tip is pointed and in use its point is driven into the mortar between adjacent bricks by blows applied to the shaft either by a hand or machine tool hammer.

The wheeled chisel referred to above has proved very successful in removing mortar from walls that are to be repointed. Generally very little damage is done to the bricks from between which the mortar is to be removed, but in some circumstances the edges of the bricks adjacent the mortar are broken away. For example, where a wall has previously been partially repointed the mortar used for repointing can be stronger than the bricks themselves and therefore if the chisel tip is driven into such mortar it can happen that relatively large portions of the adjacent brickwork can be broken away with the mortar.

It is an object of the present invention to obviate or mitigate the problem outlined above.

According to the present invention there is provided a wheeled chisel comprising a body, a working tip extending from the body, wheels mounted on the body to enable the body to be supported in a predetermined orientation on a grooved surface with the working tip extending to a predetermined depth into a groove in the surface, and a shaft to which blows may be applied to drive the body on the wheels in a predetermined direction, wherein the working tip defines a leading edge which is located on the body such that, when the body is supported on a surface with the tip extending into a groove in that surface, the leading edge extends into the groove either substantially perpendicular to the surface or rearwardly relative to the said predetermined direction in which the chisel is driven when blows are applied to the said shaft.

Thus, in contrast to the chisel described in British Patent Specification GB-A-2207380, there is no sharp point on the working tip of the chisel and the risk of hard mortar being levered out of the groove and carrying with it the edges of adjacent bricks is effectively removed. Despite the fact that such problems generally only occur in the case of very hard mortar which it might have been thought required a relatively sharp chisel point to be broken away, it has surprisingly been found that the use of a working tip having a leading edge that extends substantially perpendicular to the direction of advance of the chisel nevertheless readily removes mortar without risking damage to the surrounding brickwork.

Preferably, the leading edge is provided with teeth to improve the rate at which the mortar is broken up. For example, the leading edge may have a central groove extending along its length and transverse grooves extending across the full width of the leading edge so that teeth are defined on either side of each transverse groove.

Preferably, the leading edge is substantially straight and, when the chisel is placed on a supporting planar surface with the tip extending into a groove defined in that surface, the leading edge -subtends an angle of from 0 to 150 with a normal to that surface.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a side elevation of an embodiment of the present invention; Fig. 2 is a view of the body of the embodiment of Fig. 1 taken in the direction of lines 2-2; Fig. 3 is an illustration of the body of the embodiment of Fig.

1 taken on lines 3-3; Fig. 4 is a view of the body of the embodiment of Fig. 1 taken on the lines 4-4; and Fig. 5 is a section on the lines 5-5 of Fig. 3.

Referring to the drawings, the illustrated embodiment of the invention comprises a body 1 from which a shaft 2 received in a blind bore 3 projects. The shaft 2 is only shown in Fig. 1. The body 1 has apertures 4 formed therein into each of which a respective axle pin (not shown) is inserted. Wheels, the outer diameters of which are indicated by broken lines 5, are then mounted on the pins received within holes 4.

A working tip 6 is supported on the end of the body remote from the shaft 2. The working tip extends away from the body in a direction such that, if the wheels and body are positioned on a flat surface indicated by broken line 7, the working tip 6 projects to a predetermined depth below that surface. The depth of penetration may be determined either by appropriate positioning of the holes 4 or by appropriate selection of the diameters of the wheels 5.

The working tip 6 defines a leading edge 8 down the centre of which a groove 9 is formed. Transverse grooves extend across the leading edge and the groove 9 and thus a series of teeth 10 are defined along each side of the leading edge 8.

The leading edge 8 extends in a direction such that angle (a) is defined between the leading edge and a line 10 that is perpendicular to the surface 7. It is preferred that the angle (a) is within the range of 0 to 150. Thus it can be seen that the leading edge 8 extends downwards into the groove and rearwardly relative to the direction in which the chisel is driven when the shaft 2 is struck.

Claims

CLAIMS:

1. A wheeled chisel comprising a body, a working tip extending from the body, wheels mounted on the body to enable the body to be supported in a predetermined orientation on a grooved surface with the working tip extending to a predetermined depth into a groove in the surface, and a shaft to which blows may be applied to drive the body on the wheels in a predetermined direction, wherein the working tip defines a leading edge which is located on the body such that, when the body is supported on a surface with the tip extending into a groove in that surface, the leading edge extends into the groove either substantially perpendicular to the surface or rearwardly relative to the said predetermined direction in which the chisel is driven when blows are applied to the said shaft.

2. A wheeled chisel according to claim 1, wherein the leading edge is provided with teeth.

3. A wheeled chisel according to claim 2, wherein the leading edge has a central groove extending along its length and transverse grooves extending across the full width of the leading edge so that teeth are defined on either side of each transverse groove.

4. A wheeled chisel according to any preceding claim, wherein the leading edge is substantially straight and, when the chisel is placed on a supporting planar surface with the tip extending into a groove defined in that surface, the leading edge subtends an angle of from 0 to 150 with a normal to that surface.

5. A wheeled chisel substantially as hereinbefore described with reference to the accompanying drawings.