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## ENGINEERING GRAPHICS 1E7

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**ENGINEERING GRAPHICS1E7**Lecture 5: Isometric Projections**Isometric Terminology**• The three coordinate axes are called isometric axes • Any line parallel to isometric axes is called isometric line • A non-isometric line is a line not parallel to any one of the three isometric axis • In isometric projection of cube, the faces of the cube and any plane parallel to them is called isometric planes**Notes**• Objects composed entirely of isometric lines can be drawn by taking all measurements parallel to main edges of the enclosing box. • In an isometric drawing, an angle never appears in its true size. • Non-isometric lines are drawn by transferring the ordinates (which are on isometric lines) of the end of the lines**Objects with Normal Surfaces**Make an Isometric Drawing with corner A at the bottom**NON-ISOMETRIC LINE**Objects with Oblique Surfaces • Make an Isometric Drawing with corner A at the bottom**Objects with Non-isometric Lines**• Make an Isometric Drawing with apex A facing front**Objects with Non-isometric Lines**• Non-isometric lines are drawn with box construction and offset measurements • Non-isometric lines are not drawn in true length in isometric drawing (BA is shorter than CA in this drawing)**Irregular Objects**• Make an Isometric Drawing of the following irregular object (pyramid)**Irregular Objects**• OA and OB offsets help to locate apex O • Complete box construction may not be needed in each case**Notes**• Axonometric projection shows all 3 dimensions, length, width and height • The isometric lines are only drawn to scale. • Inclined and oblique surfaces are drawn using end coordinates • Angles, irregular curves require special techniques • Box construction and offset measurements are common methods