Technical Drawings and SketchesIntroductionThe entire world depends upon technical drawings to convey the ideas thatfeed today’s industrialized society. Architectural, structural, electric,electronic, machine, plumbing, and piping drawings are all forms ofmechanical/technical drawings. When rendering technical drawings, accuracy,neatness, technique, and speed in execution are essential. Inaccurate drawingscould be worthless or lead to costly errors.TechnicalTechnical drawing is a necessarily broad term that applies to any drawing useddrawings andto express technical ideas. Technical drawings are usually mechanicallysketchesrefined by using straightedges, triangles, and drafting instruments. Many ofthese drawings begin as a form of sketching. Technical sketching is a freehandsketch. The only equipment required to execute technical sketches are softpencils in the F to HB range, paper, and an eraser. The novice sketcher mayfind paper that is cross sectioned with ruled lines beneficial in establishingand maintaining scale. There are gridded papers, isometric papers forisometric sketches, and perspective papers for sketches requiring perspectiveavailable. When selecting an eraser, chose a soft (pink) or artgum eraser.Types ofsketchesSince technical sketches and drawings represent three-dimensional objects,your sketches should conform to one of the four standard types of projection.The four major types of projection are (1) multiview, (2) axonometric, (3)oblique, and (4) perspective. Each type of projection is covered in detail inlater chapters of this volume.Figure 4-1 shows the four types of projections.Figure 4-1.—The four typesof projections.Continued on next page4-4
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