DRAWING TRUE SHAPES - SQUARE PYRAMID

A square pyramid is shown below (Dia A). It is made from cast aluminium. A round hole goes all the way through, half way down from the apex. Drawing the circle on the side view is NOT as simple as using a compass. This is because the circle is slanting away from the viewer, on the front view of the pyramid. The process of drawing the circle accurately is shown below.

NOTE: The hole drilled through the front face is at 90 degrees to the surface. This can be clearly seen on the side view. The dotted lines representing the hole are drawn at 90 degrees

DRAWING THE CIRCLE AT ITS ‘TRUE’ SIZE

The hole through the pyramid is projected from the original circle, on to the side of the pyramid.

However, when looking at the front view, the circle is slanting away from the viewer. Therefore, it does not appear as a perfect circle. It appears slightly elliptical / swashed. To draw it accurately on the front view, divide the ‘original’ circle up with horizontal guidelines (A, B, C, D, E).

Mark each line with a ‘letter’. Then, follow the instructions opposite, projecting the lines and measurements on to the front view.

QUESTION

STAGE ONE

STAGE TWO

STAGE THREE

STAGE FOUR

STAGE FIVE

STAGE SIX

COMPLETED VIEW

MORE DETAILED QUESTION

HINT - HOW TO DRAW THE CIRCLES ON THE PLAN VIEW

Work out the ture shape of the circle on the front view using the technique shown above.

Then, project the lines to the plan view as shown below. The circles on the plan view are sketched accurately as an ellipse / oval shape. An ellipse template / stencil may be useful, otherwise draw the circles on the plan view by hand

CIRCLE TEMPLATE

STAGE ONE

FINDING THE HIDDEN DETAIL ON THE SIDE VIEW

STAGE TWO