Isometric Projection

Isometric Projection• Isometric projection is a method for

visually representing three-dimensional objects in two dimensions in technical and engineering drawings. It is an axonometric projection in which the three coordinate axes appear equally foreshortened and the angles between any two of them are 120 degrees.

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

Isometric Scale• True lengths of the edges of the

object are equally foreshortened• Correct isometric projection can be

drawn using an isometric scale (always smaller than ordinary scale)

Isometric Drawing• Isometric

Projection: Drawing prepared with isometric scale on isometric axes

Isometric Drawing: Drawing prepared with ordinary scaleon isometric axes

Steps for construction of Isometric :

Step 1Isometric sketches begin with defining isometric axes, three lines, one vertical and two drawn at 30° from the horizontal.

Step 2Three lines of the isometric axes represent the three primary dimensions of the object: width, height, and depth

Step 3Draw the rest of the isometric block.

Step 4Add details to the block starting from the front face. Then add details to the other faces.

Step 5Darken all visible lines to complete the isometric sketch. (make sure that construction lines are light)

• 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

Objects with Normal SurfacesMake an Isometric Drawing with corner A at the bottom

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

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)

• OA and OB offsets help to locate apex O• Complete box construction may not be needed in each case

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???

•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.

Cylinder

Objects with Circular Geometry

Objects with Non-Circular Curved Surfaces

• Make an Isometric Drawing of the following curved object

•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.

Presented ByEnrollment No. Name130170111090 RANA ABHIMANYU S.

130170111091 RATHAWA JAYDEVSINH

130170111092 RATHOR VIJENDRASINGH R.

130170111094 RATHWA VIKAS P.

130170111090 RUDRA PAWAN M.

Hope you enjoyed our presentation.

Thank you