Crawshaw, Fred D. (Fred Duane), b. 1874, Phillips, J. D. (James David), 1869- joint author · Chicago, New York, Scott, Foresman and company · leaf 127
irshape. Those made of celluloid have the advantage of beingtransparent and are more generally used. For accurate work itis necessary that the edges of the triangles be straight and that 122 MECHANICAL DRAWING the angles be true. The edge may be tested by the method givenfor testing the T-square.… … Fig. 125. Euling a Vertical Line 2. If when the triangle is turned over into position C, thevertical edge coincides with the line A B, the angle is 90° 3. When the 90° angle of the 45° triangle has been foundtrue, the 45° angles are true if equal. Compare the two 45° angles as follows, Fig, 127: 1.…
Mechanical drawing
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