Studies on Quantification of Sensuous Sharpness and Mechanical Sharpness of Wood Cutting Tools. VII.Effects of Shape of Knife Edge on Sharpness of Japanese Hand Plane without a Cap Iron in Wood Planing

摘要

In this paper, the effects of microbevel-shape of the knife, the amount of a gap caused by repairing botton surface, deformity of the bottom surface, and horizontal mouth opening on the occurrence of torn grain, surface quality of the workpiece, and chip discharge in planing of wood with a Japanese hand plane without a cap iron were investigated. The knife with a microbevel length (ℓR) and a microbevel angle (βR)was grinded, and its knife was equipped in the plane for this test. The depth of cut (t) was about 0.05 mm. The microbevel angle (βR) was changed from 0° (conventional knife) to 60° and the microbevel length (ℓR) was changed from 0.0 mm (conventional knife) to 0.9 mm. The materials used for this test were sugi (Cryptomeria japonica), hinoki (Chamaecyparis obtusa), white seraya (Parashorea malaanonan), and agathis (Agathissp.) in air-dry condition. Each material was plained against the grain or with the grain, at the grain angle (φ1) of about 3°. The results obtained were summarized in Figs. 6～13 and Tables 8 and 9. Using these results, characteristics of the wood-planing with a hand plane without a cap iron are discussed, comparing it with the wood-planing with a hand plane with a cap iron.