Isometric Drawing

≈ 40 min

Isometric Drawing

Orthographic views are accurate but need assembling in the reader's head. An isometric drawing shows the whole object in one pictorial view.

The rules are strict. Three axes: one vertical, and two at 30° to the horizontal. Lines parallel to these three axes are isometric lines and are drawn to true length. Lines not parallel to any axis are non-isometric lines — they are not true length and cannot be measured directly. You locate their endpoints by boxing, then join them.

Circles become ellipses. A circle on any isometric face appears as an ellipse, because the face is inclined to the viewer.

Worked example. To draw a sloping chamfer: box the full block in isometric first, measure along the isometric edges to find where the chamfer starts and ends, and join those two points. Measuring the slope itself with a ruler gives a visibly wrong angle, because that line is non-isometric.

Core checkpoint: Measure only along the three isometric axes. Everything else is found by boxing and joining.

In isometric drawing, at what angle to the horizontal are the two non-vertical axes drawn, in degrees?

Which lines on an isometric drawing are drawn to true length?

Only lines parallel to one of the three isometric axes.

All lines on the drawing.

Only vertical lines.

Only the sloping lines.

How should a sloping (non-isometric) edge be drawn?

Box the object, locate both endpoints by measuring along isometric edges, then join them.

Measure its true length and set it off with a protractor.

Estimate it by eye once the box is drawn.

Draw it first, then build the box around it.

What shape does a circular hole on a vertical face take in an isometric view?

An ellipse, because the face is inclined to the viewer.

A perfect circle, since holes are always round.

A hexagon.

It cannot be shown in isometric.