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ENGINEERING GRAPHICS 1E7. Lecture 5: Isometric Projections. Isometric Terminology. The three coordinate axes are called isometric axes Any line parallel to isometric axes is called isometric line
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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