Cones

Cones are shapes that have a circular base and come to one point at the top.

Cones The Plan of a full cone is a circle while the Elevation and End Elevation are triangles. Plan ElevationEnd Elevation

Cones In your exam it is very rare for you to be asked to draw a cone that has not been cut. The problems we face are similar to those of a cylinder. We have to construct edges in order to project the cut across the different views. We will now work through an example to show how this is done.

Cones This is an executive brass desk tidy. It is made of a cone shape with the top cut off. You will be given the elevation of the desk tidy. From it you have to draw the end elevation, plan and the development of it.

Cones - the Plan Elevation This is the elevation. You have to draw the plan from it.

Cones - the Plan We know that the base of a cone is circular so we can draw the base of the cone on the plan first. Elevation Extend the centre line from the elevation vertically up the page

Cones - the Plan Elevation Now we need to construct a clockface on the plan.

Cones - the Plan To do this we use a 30/60 set square and draw a clockface on the circle. Plan Elevation Now we need to construct a clockface on the plan.

Cones - the Plan To do this we use a 30/60 set square and draw a clockface on the circle. Plan Elevation Now we need to construct a clockface on the plan.

Cones - the Plan To do this we use a 30/60 set square and draw a clockface on the circle Plan Elevation Now we need to construct a clockface on the plan.

Cones - the Plan Make sure you number these projection lines on the elevation Plan Now project these points down onto the elevation

Cones - the Plan Project the base of the cone up to the centre line to form an imaginary top of the cone Plan

Cones - the Plan Plan Make sure you have drawn in the projection lines from the clockface to the centre of the plan. Project the base of the cone up to the centre line to form an imaginary top of the cone. Now project these points on the elevation to this imaginary top.

Cones - the Plan From where these blue projection lines cross the cut surface, project up vertically onto the plan Plan You will find that you cannot find where lines 6 and 12 cross the projection lines on the plan. The next few slides will show you how you find these lines.

Cones - the Plan Plan Project the elevation across to construct the end elevation. The base of the end elevation is the same width as the elevation and the 2 views are also the same height.

Cones - the Plan Plan Now project horizontally across to the end elevation where the lines 6 and 12 cross the cut.

Cones - the Plan Plan Add the centre line to the end elevation.

Cones - the Plan Plan Use compasses to measure the distance from the centre line to the edge of the cone along these red projection lines. 12 6

Cones - the Plan Plan Use compasses to measure the distance from the centre line to the edge of the cone along these red projection lines. 12 6

Cones - the Plan Now you can draw the curve of the cut on the plan by joining these orange points. This is done using a smooth freehand curve.

Cones - the Plan Elevation This is the finished view of the plan without any construction lines showing. Plan

Cones - End Elevation Plan To draw the end elevation use the shape you have projected for drawing the plan.

Cones - End Elevation Plan Draw a centre line and the clockface points onto this triangle.

Cones - End Elevation Plan Use a compass to mark on the clockface points and number these

Cones - End Elevation Plan Now project across horizontally where the cut intersects each of the projection lines

Cones - End Elevation Plan Joint these points up

Cones - End Elevation This is the Elevation, End Elevation and the Plan without any construction lines shown.

Cones - the Development Now we will draw the development of the cone. A development is a flat drawing of a shape that folds up to make a 3D model of it.

Cones - the Development Plan Set the compasses to the length of a side of the elevation of the cone.

Cones - the Development Plan Now draw a curve at this radius.

Cones - the Development Plan Use the compass to mark the distances between the clockface on the plan around this curve

Cones - the Development Plan Number these marks like shown

Cones - the Development Plan Draw straight lines from these marks to the centre of the curve.

Cones - the Development Plan Use your compass to mark on each line the distance from the centre to the cut.

Cones - the Development Plan To find the length you have to project from the cut across to the edge of the cone on the correctly numbered construction lines.

Cones - the Development Plan You have to do this to see the true length of each of these measurements.

Cones - the Development Plan Once you have marked all the lengths onto the development, draw a smooth freehand curve to get the finished shape of the cut.

Cones - the Development Plan Draw in the edges of the development

Cones - the Development Plan This is the finished development and plan without any construction lines.