Page 48 - CITS - ED - Mechanical

ENGINEERING DRAWING - CITS

The term solids of revolution is a mathematical concept and a physical requirement in geometry.
Frustums: Pyramid/cone is cut parallel to the base and the top portion is removed. The remaining bottom portion
is called frustum of a pyramid/cone.
If the cutting plane is at an angle to the axis/base, of the pyramids or cone they are called "Truncated pyramids
or cones".
Fig 5 shows frustums and truncated pyramids.
All items we use are solids. Their shapes may confirm to individual geometrical solids like prisms, cones or other
combination.
Figure 6 shows some such items.

Fig 5 Fig 6

Views of solids: When dealing with projection of plane figures earlier was stated that solids are enveloped by
planes and therefore drawing the views of solids would actually mean drawing the views of planes the solids are
composed of.
The faces of solids which are parallel to the planes of projection will be seen in true shape in the respective planes.
When planes are not parallel to the plane of projection the views will have a disorted look.
Figures 7,8,9,10,11,12 & 13 indicate the plan, elevation and end view of some solids for the position defined
against each.

Fig 7 Fig 8

Fig 9 Fig 10

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CITS : Engineering Drawing (Mechanical) - Exercise 4 CITS : Engineering Drawing (Mechanical) - Exercise 4