Technical Drawing 2, WASSCE (SC), 2017

Question 4

 

(a) Construct a square and a heptagon on a common base of 40mm.           

(b) The front front elevation and the plan of a regular hexagonal prism are shown below.  Draw the auxiliary plan on plan X1Y1.  Show all hidden details.

Observation

 

This question require candidates to construct a square and heptagon using general method for both on a common base.
Most of the candidates attempted this question and got it right.

 

(A)CONSTRUCTING THE SQUARE AND HEPTAGON

Candidates were expected to:

(i)draw the given base NG = 40;           

(ii)construct the square, MNGP on line NG;      

(iii) bisect line NG and drawing its perpendicular bisector;

(iv)draw the diagonal NP or a line at 45o to NG to intersect the bisector at  point 4;          

(v)draw arc NP with radius NG at G or a line at 60o on NG to intersect the bisector at point 6;           

(vi)bisect the distance between points 4 and 6 to locate point 5; 

(vii)use the distance between points 4 and 5 (or 5 and 6) to Point 7;  

(viii)use radius N7 or G7 at point 7 to describe a circle;   

(ix)use side NG as radius to mark off points on the circle and joining the points into a heptagon;       

(x)draw neatly.

The solution is shown below

ALTERNATIVE METHOD

 

(B) This question requires candidates to draw the auxilary plan of a given component.

The three major steps involved are:

  • correctly locating the X1Y1  axis
  • projecting lines from the front elevation
  • transferring ordinate dimension from the plan to draw the auxiliary plan

 

Most of the candidiates that attempted tis question did not get it right.

 AUXILIARY PLAN

Candidates were expected to:

  • draw the given plan;
  • project from the plan to draw the front elevation;  
  • draw the given elevation;  
  • draw the axis X1Y1 at  60o to the horizontal;
  • project lines from the front elevation at 90oto the X1Y1axis;
  • transfer the corresponding ordinates from the plan to the X1Y1axis;
  • locate the points of the auxiliary plan and join the points for the auxiliary plan;         
  • indicate all hidden details;     
  •  draw neatly

The solution is shown below: