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ENGINEERING GRAPHICS
Isometric Projections

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### Presentation1 of eg

1. 1. Prof. Ketaki sukala Presentation BY 130840119097 :- Ravi Rathod 130840119126 :- Yash bhathawala
2. 2. What is ISOMETRIC? • It is a method of producing pictorial view of an object showing all three faces of the object simultaneously. • It is a type of parallel projection • It is a type of axonometric projection
3. 3. Axonometric Projections • Observer at infinity • Projectors parallel to each other and perpendicular to projection plane • Object is inclined with respect to projection plane
4. 4. Types of Axonometric Projections Isometric Projection Dimetric Projection Trimetric Projection
5. 5. Isometric Projections • All angles between axonometric axes are equal • The three coordinate axes of the object appear equally foreshortened (about 3/4th of true length) • The angles between any two of the three coordinate axes is 120°
6. 6. 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
7. 7. Isometric Drawing Isometric Projection: Drawing prepared with isometric scale on isometric axes Isometric Drawing: Drawing prepared with ordinary scale on isometric axes
8. 8. Steps: Step 1 Isometric sketches begin with defining isometric axes, three lines, one vertical and two drawn at 30° from the horizontal.
9. 9. Steps: Step 2 Three lines of the isometric axes represent the three primary dimensions of the object: width, height, and depth
10. 10. Steps: Step 3 Draw the font face of the isometric block.
11. 11. Steps: Step 4 Draw the rest of the isometric block.
12. 12. Steps: Step 5 Add details to the block starting from the front face. Then add details to the other faces.
13. 13. Steps: Step 6 Darken all visible lines to complete the isometric sketch. (make sure that construction lines are light)
14. 14. • Axonometric projection shows all 3 dimensions, length, width and height. • The isometric lines are only drawn to scale. Objects composed entirely of isometric lines can be drawn by taking all measurements parallel to main edges of the enclosing box. • Non-isometric lines are drawn by transferring the ordinates (which are on isometric lines) of the end of the lines • Inclined and oblique surfaces are drawn using end coordinates. Box construction and offset measurements are common methods • In an isometric drawing, an angle never appears in its true size. Angles, irregular curves require special techniques
15. 15. Objects with Normal Surfaces Make an Isometric Drawing with corner A at the bottom
16. 16. Objects with Normal Surfaces
17. 17. Objects with Oblique Surfaces • Make an Isometric Drawing with corner A at the bottom NON-ISOMETRIC LINE
18. 18. Objects with Oblique Surfaces
19. 19. Objects with Non-isometric Lines • Make an Isometric Drawing with apex A facing front
20. 20. 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)
21. 21. Irregular Objects • Make an Isometric Drawing of the following irregular object (pyramid)
22. 22. Irregular Objects • OA and OB offsets help to locate apex O • Complete box construction may not be needed in each case
23. 23. Objects with Circular Geometry • A circle in a orthographic projection will appear as an ellipse in an isometric drawing. • Instead of actual ellipses often approximate ellipses are drawn for isometric drawing. • Four-centre ellipses are used to approximate ellipses on isometric planes. • How to draw four-centre ellipse???
24. 24. Approximate Ellipse • Draw the isometric centre lines of the circle. Using the centre lines, draw an isometric square with sides equal to the diameter of the circle. • From the near corners of the box, draw two large arcs with radius R, using the two red points as centres. • Draw the two smaller arcs with radius r, using two green points as centres.
25. 25. Cylinder
26. 26. Objects with Circular Geometry
27. 27. Objects with Non-Circular Curved Surfaces • Make an Isometric Drawing of the following curved object
28. 28. Objects with Non-Circular Curved Surfaces •A line that appears as a noncircular curve in a normal orthographic view of an object appears as a non-isometric line in an isometric drawing. •Curves may be drawn using a series of points by measuring along the normal lines in the orthographic view (offset measurements) and transferring these points on isometric drawing. Accuracy increases with number of points.