Orthographic Projections, ContinuedIsometricdrawingIsometric drawings are drawn using an ordinary scale (not an isometric scale)to lay out measurements. Images in isometric drawings are about 25 percentlarger than if rendered as an isometric projection using an isometric scale.Proportion between the projection and drawing is the same. Pictorially, anisometric projection and an isometric drawing appear the same. However, aprojection is foreshortened and the drawing is full scale, making it easier tocreate isometric drawings.IsometricdrawingpracticesBegin an isometric drawing by locating the isometric axes. All remainingmeasurements are made parallel to the isometric axes. You cannot set offany measurements along diagonal or nonisometric lines. Use offset orcoordinate measurements to lay out inclined or oblique surfaces or edges.Position of theisometric axesThe position of the isometric axes depends on the position the object isnormally viewed. You may position the isometric axes in any desiredlocation so long as there remains 120° between the axes. Place the long axishorizontally for the best effect in drawing long objects.Figure 6-16 shows how changing the position of the isometric axes changesthe object view.Figure 6-16.—Changing isometric axes.Continued on next page6-20
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