True Shapes The Cylinder

 This type of drawing is asked to be drawn as part of a cut, prism, pyramid, cylinder or cone.  It shows the actual shape of a sloping surface.  They can be quite confusing but are not as hard to produce as they look.

 As there are other slides and presentations depicting how to draw cut prisms, pyramids, cylinders and cones we are not going to show you how to do these things in this slideshow.  Instead we will focus on producing the true shapes.

Here we will draw the true shape of the sloping surface.

Draw 2 lines at 90° to the cut from the bottom and top of the cut.

Construct a clockface on the plan.

Number the clockface on the plan.

This centre line must be parallel with the sloping face on the elevation. Add a centre line at 90° to these two lines. Draw this centre line clear of all the other views to make the true shape clearer.

Now project the lines down from each of the clock points on the plan.

Ignore any of these lines that do not travel through the cut face of the cone. These are shown pink.

Project these projection lines at 90° to the cut line on the elevation.

Use a compass to transfer the distances from the centre line to the clock face. Distances from the centre line to point 11 and point 7 are the same so can be marked on at the same time. Number the corners to stop you getting confused. 11 7

Repeat for all the points

Draw a smooth freehand curve joining these points. Now join points 7 and 11 with a straight line.

Here the true shape is shown more clearly.