Machine WoodWorking2, WASSCE (SC), 2016

Question 1

(a) Candidates were asked to illustrate the following timber defects: loose knot and thicknesser.
(b)State two possible results of planing a timber with a loose knot on the thicknesser.
(c)State the main function of each of the following parts of a tree: crown, trunk and roots.

Observation

(1)

(ii)

 

(b)        -           loose knots fall off and bind in between the rollers of the machine or fly and cause injury;

            -  result in kick-back;

            - are harder than the surrounding wood tissues this dull or chip the cutter;

            -           deface the finished work piece.

(c)(i)  Crown
produces nutrients to feed the tree / support the spread of branches /flowers /fruits / and seeds                                                                                                                                                                                                                             
(ii) Trunk
supports (carries) the crown / used to produce timber                      

(iii) Roots anchor the tree and absorb moisture and minerals from the soil / it prevents soil erosion.


Some of the candidates did not understand the difference between cup and cup                              shakes in timber defects. Cup defects is an artificial defect.