Use of Blueprints; Basic Navy Training Courses NAVPERS 10621

The format is approximately 5.25 inches by 7.75 inches. vi, [2], 127, [1] pages. Illustrations. Fold-out. Appendix I [Abbreviations in common use]. Appendix II. Appendix III [Twist drill sizes]. Appendix IV [Standard wire gages]. Quiz. Cover has some wear and soiling. This book was prepared as a basic reference for those enlisted men of the Navy whose duties required them to read and use blueprints. a knowledge of blueprint reading is of major importance to those men in the artificer and seaman branches responsible for the operations, maintenance, and repair of equipment. Whether the job involves work on engines, gun mounts, boilers, steering gear, winches, or computers, the Navy technician consults blueprints for the information he needs to keep the gear and equipment in shipshape condition. the book begins with a broad picture of the uses and kinds of blueprints. It explains fully the language of the blueprint--lines, sections, symbols, dimensions, conventions, notes, and titles. Emphasis is placed on the reading and use of orthographic detail drawings and the proper procedure to follow when making layouts on material. One practice layout job is described step-by-step, and another is inserted as a challenge to the reader. A blueprint is a reproduction of a technical drawing or engineering drawing using a contact print process on light-sensitive sheets. Introduced by Sir John Herschel in 1842, the process allowed rapid and accurate production of an unlimited number of copies. It was widely used for over a century for the reproduction of specification drawings used in construction and industry. The blueprint process was characterized by white lines on a blue background, a negative of the original. The process was not able to reproduce color or shades of grey. This is a simple process for the reproduction of any light transmitting document. Engineers and architects drew their designs on cartridge paper; these were then traced on to tracing paper using India ink for reproduction whenever needed. The tracing paper drawing is placed on top of the sensitized paper, and both are clamped under glass, in a daylight exposure frame, which is similar to a picture frame. The frame is put out into daylight, requiring a minute or two under a bright sun, or about ten minutes under an overcast sky to complete the exposure. Where ultra-violet light is transmitted through the tracing paper, the light-sensitive coating converts to a stable blue or black dye. Where the India ink blocks the ultra-violet light the coating does not convert and remains soluble. The image can be seen forming. When a strong image is seen the frame is brought indoors to stop the process. The unconverted coating is washed away, and the paper is then dried. The result is a copy of the original image with the clear background area rendered dark blue and the image reproduced as a white line. …