Читать книгу The Handyman's Book of Tools, Materials, and Processes Employed in Woodworking - Paul N. Hasluck - Страница 50

Sometimes in cutting wood the surface left is found to be extremely rough, even though the chisel be as sharp as it is possible to make it. This is due to the crushing stress having been too great to be confined to the immediate neighbourhood of the cutting edge, so that it has disturbed the material for some little distance round it. This difficulty is overcome, practically, by giving a compound motion to the chisel, drawing it sideways as well as thrusting it forward. In this way the jaggedness—which always exists, however unapparent—of the edge acts like a saw upon the fibres, and thus relieves the crushing stress, with the result that in making the cut less force is expended. The benefit of this action is more pronounced in the case of the knife than in that of the chisel, as the former permits of a freer sideways motion.