Figure 43
Design of tool for testing the hardness of woods by indentation.
The wood to be tested is cut square with the grain into rectangular blocks measuring 2" × 2" × 6". A block is placed on the platform and the end of the punch forced into the wood at the rate of 0.25 inch per minute. The operator keeps moving the small handle of the guard plate back and forth until it tightens. At this instant the load is read and recorded.
Two penetrations each are made on the tangential and radial surfaces, and one on each end of every specimen tested.
In choosing the places on the block for the indentations, effort should be made to get a fair average of heartwood and sapwood, fine and coarse grain, early and late wood.
Another method of testing by indentation involves the use of a right-angled cone instead of a ball. For details of this test as used in New South Wales see loc. cit., pp. 86-87.
CLEAVAGE TEST
A static testing machine and a special cleavage testing device are required. ([See Fig. 44].) The latter consists essentially of two hooks, one of which is suspended from the centre of the top of the cage, the other extended above the movable head.
