Patent GB-485112-A (GB)
Title: An improved plumb-rule and line-holder for the use of bricklayers
IPC: G01C15/00
Filed: 1936-11-16
Abstract: 485,112. Line-holders for bricklaying. GORDON, T: Nov. 16, 1936, No. 31232. [Class 20 (ii)] A device for use in bricklaying comprises a shank a, means for rigidly fixing said shank in a vertical cavity in the brickwork at a partially-erected corner of a wall, and laterallyprojecting means which is slidable on the shank and is adapted to support both a plumbline to permit the accurate setting of the shank, and a horizontal gauge line whereby the levels of the brick courses are determined. The device comprises a hollow octagonal shank a having at its lower end a tubular portion d, which, to enable it to be expanded and contracted, is split axially into four sections and enclosed by an externally-ribbed rubber casing e ; the rubber casing e comprises upper and lower portions which are slipped over the split tube d and are cemented and vulcanized together at their open ends to form a continuous casing. The shank a and split tube d are connected together by a spindle g which also serves for expanding and contracting the tube d and casing e. A wing-nut f provided at the top of the shank a is keyed to the spindle g, which, at its lower end, is coupled to a sleeve j by a pivot pin h; the sleeve j is provided externally with right-hand and lefthand screw-threads for engaging a pair of cones k axially grooved to engage tapered ribs m on the interior of the split tube d. The device is positioned in the corner angle of a cavity wall and the split tube d is expanded so that it becomes wedged between the two leaves n, n<1> of the wall, the device being accurately positioned by suspending a plumb-line through a hole p<1> in the inwardly-bent portion p<2> of a lateral extension p which projects from the shank a. The member p comprises a threaded flattened bar p3 projecting from a housing r which is fitted with a rotatable knurled nut s whereby the bar is caused to slide horizontally. The housing r projects from a segmental carrier t which has internal ribs slidable in vertical grooves in the shank a and carries a flanged socket u slidable in a groove u<1> in the base of the carrier t. The socket u is provided with a spring plug v which acts as a stop projecting through either of two holes t<2> in the carrier so as to engage any one of a series of recesses w provided in the side faces of the shank. A set screw t<3> is provided in the carrier t for fixing the latter to the shank. The recesses w in the different faces of the shank a are differently spaced so as to correspond to the different heights of courses of brickwork, and the spring plug v is arranged to engage with the desired series according to the wall being built. In erecting a wall, the brickwork at each corner is first erected to a height not less than the height of the split-tube portion d of the device, and one of the devices is positioned in each corner of the building. Each of the members p is then lowered until the portion p<2> rests upon the surface of the uppermost brick of the outer layer of the wall with the hole p<1> in exact register with the extreme outer edge of the brick. A line is then stretched between the devices, being looped to pass through the holes p<1> and engage with the hooks p<4> at the ends of the members p, and the brickwork between the courses is then erected to the level of the line, which, together with the members p, is subsequently raised course by course by suitable adjustment of the set-screw t<3> and spring plug v so as to cause the latter to engage each of the recesses w of the desired series. In erecting a solid wall, the devices are inserted in vertical cavities provided in the brickwork at the partially-erected corners of the building.