Metal Works 2, WASSCE (SC), 2018

Question 1

(a) (i) State three precautions to be observed when using the hacksaw blade.

(ii) State one advantage of the adjustable hacksaw over the fixed hacksaw.

(b) State two differences between a four jaw chuck and three jaw chuck

Observation

Most of the candidates were not able to state one advantage of the adjustable hacksaw over the fixed hacksaw. The expected responses to question 1 are as given below.

(i) Stating three precautions to be observed when using the hacksaw blade
Choose the right type of blade.
Fit the blade in the frame with the teeth pointing away from the handle
Ensure that the blade is neither under tightened nor over tightened.
Start cutting with light strokes using the thumb as a guide.
Use the full length of the blade.
Keep the blade straight in the cut.
Finish off cuts with light strokes.
Do not exert too much pressure on the blade.

(ii) One advantage of adjustable hacksaw over the fixed hacksaw
The adjustable frame can be adjusted to take blades of different lengths.

Stating the two differences between a 4-jaw and a 3-jaw chuck

4-Jaw chuck 3-Jaw chuck

Each jaw moves independently.
Has greater gripping effect.
Can hold both regular and irregular work.
Jaws are reversible.
Can grip work either externally or internally.

Jaws move simultaneously.
Has less gripping effect.
Limited to cylindrical and hexagonal work.
Jaws are not reversible.
Holds work only externally.

(c)Sketching the parting off tool