In the previous paper the essential cutting force data such as to predict the power requirements for a chain saw engine over a large portion of its operating range at forest operation was absent with respest to hard woods which belong to higher density wood species. Therefore, cutting experiments were carried out to accomplish these parts. The results were as follows:
1) Four types of cutter tooth which had been investigated in part 2 were re-examined using 3 kinds of wood species such as katsura, Japanese elm and white oak which can be seen in Hokkaido, northern parts of Japan. The obtained characteristics of cutting forces in the radial-tangential plane with 12 combinations showed fairly good approximation to the cutting of spruce and could be represented by hyperboloid regression equations with respect to the speed ratio λ. Thereupon, mathematical models for the analytical determination of cutting horsepower were proposed in table 2.
2) As the result of reexamining specific cutting resistance forces f_H and f_V the ranking of 4 types of cutter tooth got at the cutting of spruce were found not to be applied to these hard woods. The difference will come from the characteristics of wood structure of particular species and types of cutter tooth tested.
3) In the grooving by saw-chain cutter tooth, the side wall of a kerf was cut by the side plate edge and the bottom of that was cut by the top plate edge. Therefore, the magnitude of cutting forces due to the bottom of the kerf seems to dominate the differences of total cutting forces against with the same depth of cut.
4) From this viewpoint, the adaptability of 4 types of cutter tooth to the different kinds of wood species were reexamined. As a result, chipper type saw-chain (51CP) which has a large curved side plate was suitable for the wood species having a gradual transition from early to late wood. Chisel type saw-chain (72LP & 76LP) which have squareshaped junction of both plate edge was suitable for the wood species having clear annual rings such as spruce which belonged to soft woods. Semi chisel type saw-chain (72DP) which have a small radious junction of both plate edge was suitable for cutting either soft and hard woods.