Mechanical drawing self-taught: comprising instructions in the selection and preparation of drawing instruments. Elementary instruction in practical mechanical drawing. Together with examples in simple geometry and elementary mechanism, including screw threads, gear wheels, mechanical motions, engines and boilers (1889)
, lines to represent the topsand bottoms of the thread, a template to draw thecurves by is required. To get these curves, two half-circles, one equal in diameter to the top, and one SCREW THREADS AND SPIRALS. 157 equal to the bottom of the thread, are drawn, as inFigure 208. These half-circles are… … Fig. 208. then divided off by vertical lines into as many equaldivisions as the half-circles are divided into, as bythe lines a, b, c> etc., to 0. Of these, the seven from a,to h, correspond to the seven from a to g\ and arefor the top of the thread, and the seven from i to 0correspond to the…
Mechanical drawing
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