

Isometric 

Isometric is a mathematical method of constructing a 3 dimensional
object without using perspective. Isometric was an attempt to make drawings
more realistic. The mathematics involved mean that all lengths when
drawn at 30 degrees can be drawn using their true length (in other words
lines aren't shortened as with oblique drawings). An isometric drawing
shows two sides of the object and the top or bottom of the object. All
vertical lines are drawn vertically, but all horizontal lines are drawn
at 30 degrees to the horizontal. Isometric is an easy method of constructing
a reasonable '3 dimensional' images.




Below is an object showing how the isometric lines are formed.






To draw in isometric you will need a 30 / 60 degree set square (As
illustrated). These can be purchased from all major stationary stores.




To help you it is also possible to use a grid paper underlay sheet
to act as a guide for your drawing, this is shown below.




Here are some examples drawn using an isometric grid: 











The steps below show how to draw a box in isometric.
Initially when you first start using isometric it can be useful to
use a simple box as a basic building block a guide to help you draw
more complicated shapes.






1. Draw the
front vertical edge of the cube. 











1. Draw the
front vertical edge of the cube. 











3. Draw in the
back verticals. 











4. Drawn in
top view with all lines drawn 30 degrees to the horizontal 








Drawing more complicated shapes






Orthographic
Angle Bracket 







This simple example shows you how you can use a box to help you accurately
draw a more complicated shape. The object we are going to draw is Lshaped
as illustrated by the engineering drawing (above)






The first step
is to draw our guide box. This box is the size of the maximum
dimensions.
In this case, 50 mm long, 25 mm wide, and 50 mm high. Draw the
box in very lightly.
When we have the final shape we can darken the lines. 











To get the Lshape
we need remove an area from this box.
Draw a box 40 x 10 x 50 mm, the shape that needs to be removed
from the box to create the shape we require. 











Circles in isometric don't appear circular. Instead they are skewed
and are actually elliptical. There are several methods of constructing
circles in isometric. By far the easiest method is to use an isometric
circle template which can be bought from most good art shops. These
templates contain a number of isometric circles of various sizes. If
you decide not to buy a template then you must construct a circle.


Constructing an isometric circle






1. First draw
an isometric square. Draw in the diagonals, a vertical and a line
at 30 degrees from the midpoint of the sides as illustrated 











2. Place your
compass point on the intersection of the horizontal line and the
vertical line.
Draw in a circle which touches the edges of the box. 











3. To draw the
next section of the isometric circle place your compass point
on the corner of the isometric 'square' and draw in the arc as
illustrated. 











4. Complete
the circle using the appropriate technique. 








