Most candidates were able to:
- name types of wood screws;
- sketch the screws;
- label the parts of the screw;
- state the advantages of plywood over solid wood.
However, they were unable to explain the given gluing terms (shelf life, pot life and cramping time). The expected response to question 3 is as given below:
(a) (i) Types of wood screw are:
- countersunk head screw;
- raised head or oval screw;
- round head screw;
Philips head/Podzi drive screw/star head.
Sketch of the screw
(b) Advantages of plywood over solid wood
- Plywood is more uniform in strength than solid wood.
- Plywood is more economical than solid wood in the use of valuable wood.
- It is easier to bend plywood than solid wood for curved work.
- Plywood is more durable than solid wood.
- Plywood can be obtained in larger sheets than solid wood.
- Plywood can be nailed at the edges without splitting while solid wood cannot.
(c) Explanation of Gluing Terms
It is the length of time a glue can be stored between manufacture and mixing for use before it deteriorates due to slow chemical action.
It is the length of time the glue can remain usable after mixing.
- Cramping Time It is the length of time a job should be left in the cramps before it can be safely removed.