Technical Drawing 2, WASSCE (PC), 2017

Question 1

 

Figure 1 above shows a metal bracket.  Draw full size, the bracket showing all centre of the arcs, circles and points of tangency.

Observation

 

The question require candidates to reproduce the given pattern which
involves drawing of lines, arcs and circles to be tangential.
         
Many of the candidates attempted this question but most of them could not reproduce the pattern correctly.

Candidates were expected to do the following:

TANGENCY

(i)locate centres A, B and C;

(ii)draw 5 centre lines; 

(iii)draw circles Ø55, (R55 alternate B), Ø20, Ø26 and Ø30;

(iv)draw arcs R20 and R30;

(v)locate centre for arc R70 (42 ½ from A and 50 from B)  or (15 from A, 50 from B – alternate B);      

(vi)draw arc R70 tangential to circles Ø55 and R20 (or circles R55 and R20);

(vii)locate centre for arc R32  (59½ from A  , 62 from C) or (87 from A; 62 from C alternate B);

(viii).draw arc R32 tangential to circles Ø55 and R30 (or circles R55 and R30 – alternate B);

(ix)draw 2 straight lines tangential to arcs R20 and R30;      

(x)use correct scale 1 : 1;      

(xi)draw neatly.

The solution is shown below: