Observation

(A) This is a question on isometric drawing. Candidates were given an orthographic projection and were required to convert it to isometric drawing.
The drawing includes circles and holes which must be shown in isometric. Many of the candidate attempted this question and performed fairly well, but most of the candidate could not draw the circle isometric and also could not indicate the holes which must be shown in hidden details.

Candidates were expected to do the following:

ISOMETRIC DRAWING
1. Use isometric axes;.
2. Make X the lowest point;.
3. Use the isometric box (L=70,W=70,H=75);.
4. Draw circle F;.
5. Draw circle G;
6. Draw face H;.
7. Draw face J;.
8. Draw face K;.
9. Draw face M and L;.
10. Draw 8 isometric centre lines
11. Draw 10 hidden details;.
12. Indicate X as the lowest point;.
13. Draw neatly

The solution is shown below:

(B) This question plotting the locus of a link mechanism. Many candidates attempted the question and their performance was okay.
Candidates were expected to do the following.

LINK MECHANISM
1. Copy the given mechanism (crank AO, rod AB, direction of movement, point C at correct position, centre lines (1 hor., 1 vert.).
2. Draw the circle R35 and divide it into 8/12 parts;.
3. Draw the different positions of rod AB on crank AO;.
4. Mark out the different positions of point P on rod AB;.
5. Join the points P into a smooth curve;.
6. Show quality;

The solution is shown below.