Wallis, Rolland S. [from old catalog], Iowa state college of agriculture and mechanic arts, Ames. Dept. of engineering extension. [from old catalog] · Ames, Iowa, Engineering extension department, Iowa state college · leaf 14
(a) (b) (c) Fig. 12.—Ruling pens. triangle or French curve. The usual pattern is indicated in Fig. 12a,both a front and side view being shown. When the spring-blade is released such a pen will open as shown in 11 Fig. 13a. Various quick-opening devices which facilitate the cleaningof the pen nibs… … Fig. 13.—Various ruling pens opened for cleaning. The width or weight of the line produced depends on the distance be-tween the nibs or points, this distance being adjusted by the thumbscrew. The pen should be held in a vertical plane containing theline being ruled, and with the top inclined in the…
Mechanical drawing
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