GB771607A - Machine for locating points on a surface - Google Patents

Abstract

771,607. Mathematical drawing-appliances. NAPIER & SON, Ltd., D. June 7. 1955 [June 23, 1954], No. 18472/54. Class 97(3) A machine for locating points on a plane surface with reference to two co-ordinating axes comprises a first guide member having a straight guide element which may be arranged parallel to one co-ordinate axis, a first carriage arranged to cooperate with the guide element for linear movement thereon and connected to a second guide member having a second straight guide element arranged parallel to the other co-ordinate axis and a second carriage co-operating with the second guide element and provided with means for locating a point on the plane surface, and includes a manually operated gear attached to each carriage and arranged to co-operate with a toothed rack fixed in relation to the respective guide element, and means for disengaging the gear from the rack. As shown in Fig. 1, a base-plate 1 is clamped to the top edge of a drawing board 3. Mounted on the plate 1 are a tubular guide 4, a toothed rack 6, and a replaceable scale 7. A carriage 10 has rollers 11, 12 engaging the tubular guide 4. The carriage 10 may be moved along the tubular guide 4 by a pinion operated by means of a handle 15. This pinion may be disengaged so that the carriage may be moved by hand. A lens 13 enables the scale 7, illuminated by a lamp 14, to be observed for setting the carriage. The carriage may be held in adjusted position by friction clamp A second supporting plate 25 is rigidly fixed at right angles to the first carriage 10, and has at its end a roller 26 engaging a metal track 27 secured to the lower edge of the drawing board 3. A second carriage 30 has two pairs of spaced rollers 31, 32 engaging a guide tube 29 mounted on the plate 25, while a further roller 33 on the carriage 30 engages a second guide 28 parallel to guide 29. A handle 39 controls a rack and pinion mechanism for moving the carriage, similar to that used for moving the carriage 10, an illuminated scale and lens also being provided. A projection 45 on the carriage 30 carries a sector 46 which is spring urged into two alternative positions. In one position a spring-loaded plotting plunger 48 is operative, in the other position an eye piece 47 provided with hairlines takes the place of the plotting plunger 48. Additional scales 60, 61 each comprise an endless flexible steel belt supported on spaced rollers. In order to plot points from supplied co-ordinate data, the scales are set in accordance with the zero of co-ordinance and the carriages are adjusted. The plunger 48 is brought into operative position and depressed to mark each point as the carriages are set. To plot the co-ordinance of points on a given drawing, the lens 47 is brought into operation.