Blueprint reading; a practical manual of instruction in blueprint reading through the analysis of typical plates with reference to mechanical drawing conventions and methods, the laws of projection, etc (1919)
Fairfield, Howard Parker, 1858-, Kenison, Ervin, Waite, Edward B. (Edward Broughton), 1873-, American Technical Society · Chicago, American technical society · leaf 227
Fig. 9. 45° and 30°-60° Triangles in using a rubber or celluloid triangle take care that it lies perfectlyflat and is hung up when not in use; wThen allowed to lie on the draw-ing board with a pencil or an eraser under one corner it will becomewarped in a short time, especially if the room is hot…
Mechanical drawing · Blueprinting
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