FromIsometric Drawings

toPlans and Elevations

Isometric Projection

In isometric projection all vertical lines on an object remain vertical while horizontal lines are drawn at 30° to the horizontal. Isometric drawings are usually produced with drawing equipment to ensure accuracy.

Isometric projection distorts shapes slightly in order to keep all upright lines vertical (and because perspective is ignored). Their advantage is that they show the object's dimensions accurately and in correct proportion to each other, making it easy to draw the projection correctly to scale from a plan view.

Orthographic Projection

Orthographic projection shows complex objects by doing a 2D drawing of each side to show the main features. Orthographic drawings usually consist of a front view, a side view and a plan, but more views may be shown for complex objects with lots of detail. A drawing board and parallel motion or T-square is used to project one view from another.

Orthographic drawing may be done using first angle projection or third angle projection. The graphic below shows the differences between the two.

Most drawings that you will come across in GCSE maths will be “First Angle Projection”

How to draw this shape

Follow the method on the board using the isometric paper provided.

First draw a hexagonNow convert this to a cube

Now CUT a cube outNow rub out the unwanted lines

Finally draw in the new exposed lines

This shape needs to be drawn as plan, and elevations

To do this we need to look at three of the faces and work out what we see.

If there is any detail hidden from direct view, it is indicated by dotted lines.

Plan (from the top)

End Elevation

(from the right side)

Front Elevation (from the front)

This drawing is the shape viewed from the left side, the dotted line shows hidden detail!!

The final drawing is laid out as follows:

(PLAN)

(Front Elev.)(End Elev.) (End Elev. From left)

The PLAN is the view you would see from directly above the object.

If there is any “hidden” detail is must be shown as dotted lines to prevent confusion from actually seen detail (from the point of the observer).

From Plans and Elevations

toIsometric Drawings

It is essential to remember which part of the drawing refers to which side of the actual object!!

Plan

FrontRight Left

Using “Isometric” (triangular dotted) paper, transfer these drawings.

Note that this drawing is different from the original in that all the horizontal lines are at angles!!!

The hidden edges are shown as dotted lines.

All distances are kept correct, using the grid dots as a guide.

Now draw the Plan and elevations of the Isometric drawing on the OHT

Plan, Front and ONE side elevation (your choice)

PLAN VIEW

FRONT ELEVATION

VIEW SIDE ELEVATION

VIEW (RIGHT)

SIDE ELEVATION VIEW (LEFT)

2.5 cm

5 cm

6 cm

1 cm

1 cm

2.5 cm

1 cm 4 cm

5 cm

1 cm

1.25 cm

ISOMETRIC DRAWING