Patent GB-1232805-A (GB)
IPC: B43L13/14
Filed: 1968-07-17
Abstract: 1,232,805. Apparatus for making perspective drawings. K. A. BOWEN. 17 July, 1968 [9 Aug., 1967], No. 34024/68. Heading B6P. Apparatus for making perspective drawings comprises tables 30, 34 on which orthogonal drawings of an object are placed and two tracers 50, 52 movable over the lines of the drawings, both tracers being slidable along a member 44 movable parallel to itself across the table 34, the tracer 52 being connected by a cable 74, Fig. 2, passing over a pulley 80, Fig. 1, on a support 28 to a carriage 56 slidable along the support 28, and the carriage 56 being connected by a universal joint 60 to a telescopic lever 62 having at its lower end a point 67 engaging in a socket 68 on a slide 46 carrying the tracer 51 and movable along the member 44 or engaging a socket 70 of tracer 52. The lever 62 is connected by a parallel linkage 194 to a lever 94 pivoted at a universal joint 96 fixed relatively to support 28. If a marking device were mounted on the free end of lever 94 and a table with paper thereon could conveniently be placed adjacent to the free end of lever, movement of the tracers 50, 52 over parts of the drawings, would cause movements of the carriage 56 and lever 62 transmitted to lever 94 such that the marking device would draw a perspective view on the paper. As shown, however, a table 84 for the paper is mounted on the support 28 and the movement of lever 94 is transmitted to a pantograph 86 having a marking point 92 inscribing the perspective view on the paper. For transmitting the movement of lever 94, an arm 222 is fixed to the support 28 and carries a shaft 226 at one end of which the universal joint 96 is situated. A telescope lever 104 also pivoted at the universal joint 96 is connected by an adjustable link 334 to one arm 102 of a two-armed lever 98, 102 attached to a carriage 100 slidably and pivotally mounted on the shaft 226. The free ends of levers 98, 102 are connected by pin-and-slot connections 232 to the levers 94, 104 respectively. An extensible part 108 of lever 104 is connected by a universal joint 110 to a link 112 of pantograph 86. The member 44 has rollers engaging side guides 40, 42 on the table 34 and is of tubular form. The cable 74 is attached at one end to a coil spring 72, Fig. 2, extends through the member 44 and is adjustably secured to the tracer 52. It passes over pulleys 154, 158 on a swivelling carriage 148 mounted on the table 34 and then through a guide and pulley arrangement 78 through a member 188 adjustably mounted on the support 28. The arrangement permits of adjustment movements of the member 44 and of the table 34 relative to the table 30 as described later without alteration of the position of carriage 56. The table 30 is fixed and circular and the table 34 has an arcuate edge engaging the edge 132 of table 32 so that the table 34 can be adjusted about the table 30 according to the perpsective view required. The support 28 can also be adjusted along a slot 54 according to the angle from which the perspective view is to be taken. The table 34 is translucent and has lamps 126 underneath it for use when it is necessary to place a drawing face downwards on the table to obtain the required view. This, however, may be avoided by attaching the end of cable 74 passing over pulley 80 to a spring, whereby the carriage 56 can be attached to either vertical run of the cable 74. Holders for recording pens.-The marking device 92, Fig. 1, comprises a pen 250 and inkwell 248, Fig. 9, adjustable for height on an arm 244 connected by a leaf spring 246 to the end 242 of pantograph link 90. Another arm 254 is connected to the part 242 by a leaf spring 256 and is urged towards arm 244 by an upwardly spring-pressed screw 270, the upward movement being limited by a collar 278 on the screw. Between the end 242 and the arm 254 is an expansible fluid container 260 connected by a flexible tube 266 to a bulb 268, Fig. 1, which has to be squeezed to expand container 260 and lower the pen 250 during drawing.