MECHANICAL DRAWING

 MECHANICAL DRAWING.

In technical drawing, mechanical drawing is an optional question in WASSCE AND NECO SSCE. 

Mechanical drawing has to do with proper understanding of orthographic Projection, isometric insight view of the object as presented in 2 Dimension, sectional views of objects in 2 dimensions, Screws, lock devices and fasteners and assembly of objects. 

Most often WAEC will give a brief of how to assemble the given mechanical tool while NECO in most cases does not give a brief. Therefore, it is important that the student learn and practice more on mechanical drawing before attempting it. In my own view, mechanical drawing is simpler compared to building drawing at the school certificate level.

Find below some examples of how Mechanical drawing questions are set in WASSCE.

1. The figure below shows a bevel pulley mounting bracket, with the parts assembled, draw full scale the following views

i. Sectional front elevation on cutting Plane T-T

ii. Sectional end elevation on cutting plane S-S

iii. Plan.

The answer to the above question is shown below:

2. The figure below shows the detail of a pulley bracket assembly. Part R is held between the arms of the bracket by the pin S with the point of entry from right to the left.

Draw full size in first angle Projection the fully assembled

i. End view

ii. Sectional view in the direction of X-X

Show all hidden details on the front elevation only.

The answer to the above question is shown below

EXERCISE

Details of a pulley bracket are shown in the figure below. To assemble, each of the bushing is fitted into the bracket and pulley. These are then held in position by the spherical head pin. The washers are to be positioned correctly before assembly with a split pin.

Draw full size in first angle projection assembly

i. The plan 

ii. Sectional front elevation on X-X

iii. End elevation in the direction of arrow Y.

NOTE: Do not show the split pin.