1. ISOMETRIC PROJECTION RATHER DRAWING
DEEPAK SAMEER JHA
LOVELY SCHOOL ENGINEERING

2. WHAT DO YOU UNDERSTAND LOOKING AT THE FIGURES SHOWN BELOW?
SQUARE PLANE
RECTANGULAR PLANE
CIRCULAR
DISC C Y L I ND E R C
ONE

3. WHAT DO YOU UNDERSTAND BY?
CUBE
CUBOID

4. WHAT DO YOU UNDERSTAND BY?
IT IS NOT VERY EASY AND SIMPLE TO INTERPRET AND UNDERSTAND THE ACTUAL COMPONENT BY LOOKING AT THE ORTHOGRAPHIC PROJECTION ALONE.
SO WHAT DO WE NEED?

5. PRODUCER’S INTERPRETION OF THE DRAWING
MODEL
DESIGNER’S MIND
DRAWING
PRODUCER’S VIEW
PRODUCER’S INTERPRETION OF THE DRAWING

6. Projections: Four Basic Types
Note: Isometric is a special case of Axonometric
Orthographic Projections
Axonometric
Course emphasizes on multi-view (orthographic) and isometric (one type of axonometric pictorial) projections only
Multiview projections are a collection of 2-D views
Pictorials are 3-D
Pictorials
Oblique
Perspective

7. Isometric means ‘equal measure’.
WHAT IS ISOMETRIC PROJECTION?
Isometric projection is a type of an axonometric projection (or pictorial projection).
Isometric means ‘equal measure’.
As the name suggests, in isometric projection, all the mutually perpendicular plane surfaces of an object and the edges formed by these surfaces are equally inclined to a POP.
In isometric projection, only one view on a plane is drawn to represent the three dimensions of an object. This provides a pictorial view with a real appearance.

8. PRINCIPLE OF Isometric Projection
CUBE
Isometric Projection:
One type of axonometric pictorial (3-D) projection
‘Iso-’ means ‘equal
‘metric projection’ means ‘a projection to a scaled measure’
The three dimensions are not only shown in one view, but also the dimensions can be scaled from this drawing
START WITH A CUBE
All of the normal drawing planes (top, front, side) are equally foreshortened or tilted, and all of the major axes (X, Y, Z) are at equal rotations from each other (120 degrees apart), as in the illustration above.
And, because all of the major planes are equally foreshortened, all of the measurements in these planes are equal as well as shown above. This means that the same measuring scale may be used in drawing both the width, height, and depth of objects.
Isometric means equal measure
All planes are equally or proportionately shortened and
tilted
All the major axes (X, Y, Z) are 120 degrees apart

9. A VIDEO TO UNDERSTAND WHAT CONCEPT ARE WE ATTEMPTING TO UNDERSTAND

10. TERMINOLOGY
Isometric axes The three lines GH, GF and GC meeting at point G and making 120° angles with each other are termed isometric axes. Isometric axes are often. The lines CB, CG and CD originate from point C and lie along X-, Y- and Z-axis respectively. The lines CB and CD make equal inclinations of 30° with the horizontal reference line. The line CG is vertical.

11. LETS STANDARDIZE THE AXES
BREADTH
LENGTH
HEIGHT

12. CHARACTERISTICS OF ISOMETRIC PROJECTION
Isometric lines The lines parallel to the isometric axes are called isometric lines or isolines. A line parallel to the X-axis may be called an x-isoline. So are the cases of y-isoline and z-isoline.
Non-Isometric lines The lines which are not parallel to isometric axes are called non-isometric lines or non-isolines. The face-diagonals and body diagonals of the cube shown in Fig are the examples of non-isolines.
Isometric planes The planes representing the faces of the cube as well as other faces parallel to these faces are called isometric planes or isoplanes. Note that isometric planes are always parallel to any of the planes formed by two isometric axes.
Non-Isometric planes The planes which are not parallel to isometric planes are called nonisometric planes or non-isoplanes (or non-isometric faces).
Origin or Pole Point The point on which a given object is supposed to be resting on the HP or ground such that the three isometric axes originating from that point make equal angles to POP is called an origin or pole point.

13. Making an Isometric Sketch
Defining Axis
30o
60o
Isometric Axis
Derive the axes from a vertex of the cube

14. NOTE
NO ISOMETRIC VIEW SHALL BE DRAWN WITHOUT DRAWING THE ORTHOGRAPHIC VIEWS

15. ISOMETRIC PROJECTION OF STANDARD FIGURES

16. RECTANGLE

17. TRIANGLE

18. PENTAGON

20. CIRCLE

21. IRREGULAR SHAPES

23. Using construction lines to construct a cube.
Key rules!
All diagonal lines are at 30°.
All other lines are vertical.
Keep all construction lines very faint.

24. Using a cube to create right angle triangles1 2 3 4
Other examples

25. SOLIDS
PYRAMID
A PLANE ON ONE SIDE AND AN APEX ON THE OTHER JOINED BY TRIANGULAR PLANES
Rectangular Pyramid
PENTAGONAL Pyramid
HEXAGONAL Pyramid
CONE
PRISM
OPPOSITE ENDS ARE EQUAL JOINED BY RECTANGULAR PLANES
Rectangular Prism (Cuboids)
PENTAGONAL PRISM
HEXAGONAL PRISM
CYLINDER

26. HEXAGONAL PRISM EDGE: 20mm and 50 mm height

27. CYLINDER OF DIA 60 mm and HEIGHT 80 mm

28. Step 2 – Ellipse on Front Face
- Corner to corner to get center
Lines to Tangent Points
- Lines to tangent points
Tangent Points
Note for students that just front part of box will be shown to keep it simple in the visuals.
Sketch in lines corner to corner (along major and minor axis of ellipse) to get center point
Sketch perpendicular lines through center point to get tangent points on outside box.

29. Step 3 – Ellipse on Front Face
Sketch in Arcs
Tangent Points
Sketch in smooth arcs to join the Tangent points on Major axis and minor axis. Radius of arc on the longer diagonal is shorter than the radius of arc on the shorter diagonal.

30. Step 3 – Ellipse on Back Face and Profile
Repeat for ellipse on rear face
Draw Tangent Lines for Profile
Complete Visible Part of Back Ellipse
Note that in case on the rear side of the pipe, only a part of the ellipse is visible. So only the part which is visible is drawn with dark lines

31. A PENTAGONAL PYRAMID OF EDGE 30mm and height 60mm

32. A CONE OF DIA 60 mm and HEIGHT 80 mm

33. Object for Practice
How to derive this object from a rectangular piece of wood?
Shape it in to a rectangle with maximum dimensions (so as to fit the required object) on the three axes
Chisel out the unwanted parts…. Slides follow.
NOTE: No scale provided due to lack of measurements of blocks.
TA’s – Get the blocks from the Instructors Console and distribute them to all the tables.

34. Blocking in the Object Begin with Front Face
Height
Width
Identify the size of the front view of the object and sketch its outside dimensions on the Isometric view.

35. Blocking in the Object: Add Side Face
Height
Depth
Side Face
Once the front view outside dimensions are added on the isometric sketch, add the side view dimensions.

36. Blocking in the Object: Add Top Face
After front and side views are sketched on the isometric drawing, then add the top view.

37. Adding Detail Cut Outs – Part 1
The order of adding the details is important. They build upon each other.

38. Adding Detail Cut Outs – Part 2
Note that lines parallel to axes

39. Adding Detail Cut Outs – Part 3
Note that lines parallel to axes are drawn first, then oblique lines are determined from their intersections.

40. Darken Final Lines - Part 4
Note:
All visible edges
will be darkened
Construction lines can be left in but must be much lighter than the final lines.

41. CHAPTER 4 : ISOMETRIC DRAWING
1. Three views of shaped block are shown in Figure 1. Draw a full size isometric view of the block in the direction of arrows shown. The size of grid is 10 mm x 10 mm. All hidden details need not be shown.
FIGURE 1
LOCAL PUBLICATIONS ( A)

42. Sketch from an actual object
STEPS
1. Positioning object.
2. Select isometric axis.
3. Sketch enclosing box.
4. Add details.
5. Darken visible lines.

43. Sketch from an actual object
STEPS
1. Positioning object.
2. Select isometric axis.
3. Sketch enclosing box.
4. Add details.
5. Darken visible lines.
Note
In isometric sketch/drawing), hidden lines are omitted unless they are absolutely necessary to completely describe the object.

44. Sketch from multiview drawing
1. Interprete the meaning of lines/areas in multiview drawing.
2. Locate the lines or surfaces relative to isometric axis.

45. Example 1 : Object has only normal surfaces
Top H
Front
Top View
Regular
Side W D
Front View H
Side View
Front
Side W D
Bottom View
Reverse
Bottom

46. Example 2 : Object has inclined surfaces
Nonisometric line y q H y x x W
Front View

47. Example 3 : Object has inclined surfaces
Nonisometric line y A C y B A

48. Example 4
Regular x y B D C E F
Front View A B A C
Reverse D F E

49. Circle & Arc in Isometric
In isometric drawing, a circle appears as an ellipse.
Sketching Steps
1. Locate the centre of an ellipse.
2. Construct an isometric square.
3. Sketch arcs that connect the tangent points.

50. Circle & Arc in Isometric
Four-centre method is usually used when drawn an isometric ellipse with drawing instrument.
Sketching Steps
1. Locate the centre of an ellipse.
2. Construct an isometric square.
3. Construct a perpendicular bisector from each tangent point.
4. Locate the four centres.
5. Draw the arcs with these centres and tangent to isometric square.

51. Example 5