Cutlery – Cutting tools – Scrapers
Patent
1990-03-16
1991-10-22
Watts, Douglas D.
Cutlery
Cutting tools
Scrapers
30168, 151055, 152353, B26B 300, B26B 308, E04F 2100, E04G 2120
Patent
active
050582755
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a chisel, and in particular to a chisel for removing material from a crack defined between two adjacent bricks.
Masonary walls are generally built from bricks of regular or irregular shape with the bricks being separated by thin layers of mortar or the like. The primary purpose of the mortar is not to adhere adjacent bricks together but to provide a secure bed for one brick when it is placed upon an immediately adjacent lower brick.
Over time the mortar becomes weakened and can become seriously eroded. If this occurs it is necessary to repair the wall by removing loose mortar from the cracks defined between adjacent bricks and repointing the wall, that is inserting fresh mortar or the like into the cracks.
Traditionally, when a wall has been repointed, loose material is hacked out of the cracks between adjacent bricks using a simple pick the point of which is hammered into the mortar manually. This is a laborious process and accordingly alternative methods have been suggested. The most widely used alternative method is to insert a rapidly rotating abrasive disc into the cracks between adjacent bricks. This is a highly effective method for removing unwanted mortar but presents various problems in that it generates large quantities of dust and can be highly dangerous in that there is a tendency for the disc to act as a driving wheel and pull the disc and its associated power tool across the face of the wall. This can cause physical injury and also can damage the wall surface if the disc runs across the face of bricks making up the wall. Furthermore it is difficult with a disc to clean mortar from a crack of only limited length, such as that defined between the adjacent ends of house bricks of conventional size.
It has also been known to use simple narrow headed chisels to remove loose material from the cracks defined between bricks. Unfortunately there is a tendency either for the chisel to skate across the surface of the mortar or for it to be driven too deeply into the mortar.
It is known from German Patent Specification No. DE 1427719 to provide a wheeled carriage for cutting channels in a flat surface such as a wall. The carriage is supported on wheels that maintain the orientation and depth of penetration of a reciprocating chisel relative to the wall surface, the chisel being driven by a rotary hammer mounted in the carriage. The chisel tip is however covered by the carriage and therefore its progress cannot be monitored. Furthermore the carriage is a relative bulky structure as a result of the incorporation therein of a reciprocating hammer device and thus projects to a considerable height above the wall surface. These features are acceptable when cutting channels in, for example plasterwork, but are not acceptable for removing mortar from between bricks. In the latter case it is necessary for the user of the tool to be able to see the tool tip so as to be able to monitor its progress through mortar the consistency of which varies greatly from place to place in a single wall. Furthermore the bulky carriage structure and the location of the cutting tip beneath the carriage prevents the use of such a device in removing mortar from walls adjacent or behind for example rainwater downspouts or internal corners.
German Patent Specification No. DE 3312019 describes a device for removing mortar from between bricks using a rotary drill with a reciprocating hammer ation, the drill extending through a sleeve the end of which bears on the brick surface so as to limit the depth of penetration of the drill. Unfortunately the sleeve prevents visual monitoring of the progress of the drill bit, and if the drill bit hits a particularly hard region of mortar it can easily be thrown out of the crack so as to run across the adjacent brick surfaces.
U.S. Pat. No. 3,662,423 describes a tool for raking loose mortar from between bricks. This tool has two rollers spaced to run in respective adjacent mortar gaps, the intention being that the engagement of the rollers in the adjacent mortar gaps
REFERENCES:
patent: 864260 (1907-08-01), Rehfeld
patent: 3237235 (1966-03-01), Moody
patent: 3662423 (1972-05-01), Miller
patent: 4324042 (1982-04-01), Lipka et al.
Heyrana Sr. Paul M.
Watts Douglas D.
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