| 摘要 |
PROBLEM TO BE SOLVED: To reduce resistance and improve sharpness and durability of an edge by changing a cutting surface (a surface abutting against material)of the edge of a saw from a conventional plane to a joint type of a U shape and a U shape. SOLUTION: The cutting surface, which has been conventionally a plane, of the edge of the saw is made to be U-shaped, and further a U-shaped groove is provided in a center of the edge.
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