ENGINEERING GRAPHICS 1E9. Lecture 3: Isometric Projections. 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.
Lecture 3: Isometric Projections
Isometric Projection: Drawing prepared with isometric scale on isometric axes
with ordinary scale
on isometric axes
Isometric sketches begin with defining isometric axes, three lines, one vertical and two drawn at 30° from the horizontal.
Three lines of the isometric axes represent the three primary dimensions of the object: width, height, and depth
Draw the font face of the isometric block.
Draw the rest of the isometric block.
Add details to the block starting from the front face. Then add details to the other faces.
Darken all visible lines to complete the isometric sketch. (make sure that construction lines are light)
Make an Isometric Drawing with corner A at the bottom
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)
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.