Topic 07- Axonometric View in Engineering drawing

Introduction

Now we will discuss the axonometric view. In the case of orthographic projection and making multi-views; the method is to draw the three side of an object in three two-dimensional views. However now we will consider the opposite procedure.

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Definition

The Axonometric view is defined as a type of the orthographic projection technique. In this method we orient the object such that the three sides face will show all the features (length, height and depth). The actual dimension might be foreshortened but that case would be discussed and distinguished shortly.

Difference between View and projection

When we try to represent all three sides of an object on a straight plane. That would make its dimensions foreshortened.

If we draw the Axonometric drawing with the foreshortened length; then this would be called an axonometric projection. However, if the true dimension is used then this would make the view larger in size. This enlarged drawing would be called Axonometric view.

Note

We should consider that the same concepts are applied to the different types of axonometric drawing and require no separate understanding.

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Types of Axonometric View

Introduction

Recall that we have already discussed that for an axonometric view. We take an object (which is a cube in this example) and orient it in such a way that it would show all three sides simultaneously. Now consider one corner and the corresponding edges of the axonometric view. Now it is simply intuitive that for any one corner; there would be three edges. Geometrically, that corner can be regarded as a central point and the edges would be called the axonometric axis.

The axonometric axis makes certain angles with one another. This gives different types of such views

Isometric View

The angles between the axis are all equal which makes about 1200 each. The difference between the view and the projection is that it is derived mathematically that each dimension in an isometric view would be foreshortened about 0.82 times. This means that if the actual length is 100 mm. Then, in the isometric projection, it would be taken 0.82 x 100 mm = 82 mm. Thus, the isometric projection is smaller in size.

Note that this value derived is only for the derived for the isometric cases. Other cases are just a little more difficult to draw.

Dimetric

The two of the angles between the axonometric axes are equal but the third angle is a different one.

Trimetric

All the angles are different one. None of them are equal to each other.

Next: Topic 08