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 8
and relatively cheap, are brittleand easily chipped or broken. Steel triangles are accurate, but theyare^expensive, apt to soil or cut the drawings, and easily tarnished. Celluloid triangles are almost universally used at the present time. They are light, strong, flexible, nearly transparent easily… … Fig. 4.-Relative positions of drawing board, T-SQuare and triangles. drawn along the triangles only in the directions indicated by the ar-row™ that is, always away from the body and to the right. The lineswhich may be drawn with the 30°-60° triangle are shown combined mFig. 5j and those with the…
Mechanical drawing
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