Johnston, Philip Devereux, 1855- · New York, D. Williams Company · leaf 90
may be drawn. In Pig. 34 the pitch, or lead, islaid off on a line parallel with B D, but this is notnecessary, as the subdivisions can be made upon eitherA C, B D or the centre line E F. To drazv a helical spring: Fig. 35.—Draw the helix as in Fig. 34, which wouldbe the centre line of the spring.…
Mechanical drawing
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