Orthographic Projections, ContinuedAnglesAngles project in true size only when the plane of the angle is parallel to theplane of projection. Since the surfaces of an object are inclined toward theplane of projection, most angles will not project in true size. An angle mayproject larger or smaller than true size depending on its position to the planeof projection. Convert angular measurements into linear measurementsbefore laying them out along isometric lines. You may also use an isometricprotractor.SectionsYou may use all types of sectional views in isometric drawings andprojections. Half sections are used most often because only a quarter of theobject is removed, showing the relationship between the interior and exteriorsurfaces. When drawing a half section in isometric, draw the entire objectfirst, then remove the half section. When drawing a full section where thecutting plane passes completely through the object in an isometric drawing,draw the cutting plane first, then draw the portion of the drawing behind thecutting plane.Figure 6-19 shows a half and full section in isometric.Figure 6-19.—A half and full section in isometric.Continued on next page6-24
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