The sheet-metal worker's guide : a practical handbook for tinsmiths, coppersmiths, zincworkers, etc., comprising numerous geometrical diagrams and working patterns, with descriptive text (1888)
Crane, W. J. E. (W. J. Eden) · London : Lockwood and Son · leaf 58
46 THE SHEET-METAL WORKEr's GUIDE. ference of the protractor at 90°, e c b is, there- fore, an angle of 90°, or a right angle. Similarly F c A is an angle of 45°, or half a right angle, and G c B is an angle of 60° (the mark ° indicates a degree or degrees), and g c a is an angle of 120.° Sometimes… … same. A protractor of one of these forms is generally found in every box of instruments. To draw an angle of 60° geometrically : — With centre b (Fig. 40), and any radius, describe Fig. 40. the arc 1,2. With centre 1, and the same radius, describe the are b 3. Draw the right line, a b,
Sheet-metal work
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