Mechanical drawing; a treatise on the drawing of mechanical and machine details (1920)
Jones, Franklin Day, 1879-1967 · New York, The Industrial press; [etc., etc.] · leaf 56
n arm pivoted at the centerwhich can be swung around the circle (see Fig. 18). The INSTRUMENTS AND MATERIALS 43 smaller protractors are divided into degrees, while larger onesshow half or quarter degrees. Those with a swinging armlike the one shown in Fig. 18 are usually provided with avernier… … Fig. 16. Different Angles which may be laid off by using the 45- and30- by 60-degree Triangles than circles or arcs. Curves are generally made of celluloidand in a great variety of sizes and forms. The curves maybe parts of ellipses, spirals, parabolas, or other curves. Forspecial purposes, they…
Mechanical drawing
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