Development of a Portable Brinell Hardness Tester for Wood
Seiji HIRATA, Kaneharu MAKINO
In order to make it easy to measure the hardness of wood in woodworking classes, a portable Brinell hardness tester was developed. The tester automatically indicates the hardness of wood using a digital readout. A 3 mm steel ball was used in order to reduce the load weight which is required for pressure insertion of the steel ball. However, there is no limitation to the size of the test object or the measurement position. We obtained the following result by measuring the hardness of various wood materials The results were as follows:
(1) Even 7th graders were able to measure hardness.
(2) Because the steel ball was small it was easy to measure the difference in hardness between early wood and late wood.
(3) We confirmed that wood closer to the pith is harder than wood close to the bark.
(4) In vertical grain, the coefficient of variation along the direction of fiber is smaller than the radial coefficient of variation.
Key words : portable tester, wood, Brinell hardness, junior high school