Introduction To Technical Drawing

Technical drawing boils down to two-dimensional technical drawing (triple projection) and three-dimensional technical drawing (axonometric).

Triple Projections meansdescribing a 3D volume using a frontal, top and side view which are linked by means of a basic Ox,Oy,Oz coordinate system.

Axonometric describes a 3D volume using a 3D representation.

The difference between an axonometric and a perspective is that the lines which are parallel in real life, stay parallel in an axonometric, while the lines which are parallel in perspective converge to the same perspective point.

Also, axonometric can have a scale, which implies the drawing is proportionally smaller than the original, real-life object by a certain standardisedpercentage(100 times smaller, 50 times, 200, 20,etc.).

Examples Of Technical Drawing

Technical drawing (both triple projection and axonometric) can be combined with freehand drawing to create interesting artistic pieces.

Facades (frontal views of buildings) benefit from a higher amount of detailing in order to communicate as much information as possible – information such as materiality, the way light falls on the facade, construction details, colours, human scale, etc.

Axonometric of rooms need as much detailing as possible, to better represent the mood of the interior spaces and to move the drawing as quickly as possible from ‘a couple of construction line boxes’ to an interior space.

Keep in mind though, all these examples are still technical drawings.

They need to first be correct to respect the drawing’s scale and all the parallel edges to really be parallel… and then to be artistically expressive.

Floating Cube

The first exercise for technical drawing is a triple projection and axonometric of a simple cube, then of a cube floating 1 cm from the ground.

The top view for a simple and floating are the same, the only difference is with the frontal and side views.

The isometric axonometric is the standard type of axo you will be using 99% of times in architectural drawing.

It implies a 120-degree angle between the three axes and the same unit of measure for Ox, Oy and Oz.

Cavalier Axonometric

A cavalier axonometric is slightly different than the standard isometric axo as it has a 90-degree angle between the Ox and Oy axis and 135 degrees between Ox and Oz, Oy and Oz.

It is the easiest approach to drawing something starting from a plan as it just implies you need to rotate the plan 45 degtrees then add heights.

In comparison, an isometric axo would require you to draw the plan modified in relation to the 120-degree coordinate system and then go for heights.

Dimetric Axonometric

The dimetricaxo is unusual as it has a 90-degree angle between the Oz and Oy axis and a 135 degree between Oz and Ox, Oy and Ox.

The Ox axis also has a half the unit the other two axes have… since the name di-metric, meaning two different measurements and units.

Dimetricaxos are an alternative for the other two types – they are really not that common but can be used again as an alternative to the isometric and cavalier.

Technical Drawing Lesson – Simple Shapes

Basic two-dimensional shapes are a key element of architectural thinking as understanding them will help you break down and understand any of the more complex geometrical shapes.

After drawing basic shapes, you will start building a mental system of visually breaking down objects around you into simple shapes, and that will help you see things in three dimensions.

This, in turn, will allow you to see beyond the concrete, physical reality and start understanding the mindsets and visual language behind different types of architecture.

Like Brancusi once said ‘We draw something until we really see it’.

How To Draw A Circle

A circle is a round 2D shape with a centre and radius.

What can you potentially need to know from a circle?

Its radius, length, surface and centre.

In order to correctly draw a circle, you need a compass. You decide the circle’s centre, then its radius and that is enough.

How To Draw An Ellipse (Circle In Axonometric)

Drawing a circle in isometric axonometric is a bit more complex, and the technique of correctly constructing the ellipse is counter-intuitive.

You first need to draw a square in axonometric – we will begin with a 6 cm edge square.

Then draw the diagonals (which for a square in isometric axonometric are a horizontal and vertical line).

From the centre where these two diagonals meet you need to draw parallels to the edges of the square.

Then here comes the interesting part – you need to connect the corner of one square to the middles of the opposing edges. After these two lines intersect the horizontal diagonal, you will get two points.

From these two points, you will draw the small arches which go on the sides of the square, then draw the two large arches with lines from the top and bottom corners of the square.

Now you got a horizontal circle in isometric axonometric, next up we will draw a vertical ellipse.

The steps are exactly the same – the only thing you need to realise is that the square is going to have vertical edges and 30-degree lines and that is it.

The horizontal ellipse has both opposing edges at 30 degrees.

How To Draw A Square In Axonometric

A square is a four edged two-dimensional shape with equal edges and 90-degree angles between all adjacent edges.

A square in axonometric is really easy to draw – just keep in mind that the 90-degree angle comes out of a geometrical construction – so you need to draw a square that has parallel lines to the axonometric’s system of reference. Draw a line parallel to one of the coordinate axes, measure the square’s edge length, draw the other edge, then by means of parallel lines connect everything together.

How To Draw An Equilateral Triangle

The standard position for a triangle is with one edge perpendicular to the Ox axis. Drawing it this way will help you a lot when it comes to future descriptive geometry assignments when this triangle will represent the top view for some more complex volumes.

Draw the perpendicular edge, measure the length, draw the height of the triangle the use the standard 60-degree triangle to get an even triangle (which has three 60 degree angles).

You can do this with a compass as well – draw one edge of the triangle as vertical with the height starting from the middle and pointing towards the right-hand side.

Then from one of theend of the vertical edge draw an arch with the same length as the edge and intersect it with the height on the right-hand side.

Connect that point to the vertical edge, and you got an equilateral triangle.

Equilateral Triangle In Axonometric

Drawing an equilateral triangle in axonometric might seem more complicated as the shape does not have all edges parallel to the coordinate system.

So the best way to draw a triangle is to first draw an edge, then the afferent height, then constructs the other two edges.

You first need to have the triangle constructed in a triple projection, then copy the length of the vertical edge and of the height in axonometric and then connect the three dots adjacent to get an even triangle.

Difficulty: Complete Newbie

Video Time: 45:28

• Always keep your drawing tools in pristine condition: this will guarantee you will smudge less when drawing technical
• Technical drawing is about line clarity. So always ask yourself if your drawing has clear construction/contour/section lines
• Always keep parallel lines parallel – double check that your triangles and T square are perfectly aligned to your drawing board when drawing

• Most student think they absolutely need a mechanical pencil to draw technical. The truth is that a standard, well-sharpened 2B pencil is enough to get decent results with any technical piece
• Careful of the two pitfalls in technical drawing – smudging the page and not drawing parallel lines parallel. Be on your guard for both of these, clean up your technical drawing style
• Technical is the left-brained, problem-solving type of drawing. Even if you have this gut level reaction that you will not like technical drawing, don’t forget that  – getting better at technical will upgrade your freehand drawing as well