Square Cants from Round Bolts Without Slabs Or Sawdust

Three designs to create chips or flakes by means of end-milling, peripheral milling, and cutting with shaping lathe were tested. The experimental setup for the end-milling configuration was a Koch headrig-cutterhead equipped with two carbide-tipped knives turning at loaded speed of 62 rpm; rake angle 45?; sharpness angle 37-1/2?; and cutting-circle diameter 11-l/16 inches. Resulting pulp chips indicated shear failures caused at the time of chip formation permit gross chip to be broken into smaller uniform thickness and length. Net specific cutting energy averaged 0.011 hp minute per cubic inch of wood removed. The disadvantages of the end-milling configuration were high energy requirements, exertion of a large force normal to the longitudinal axis of the bolt, a tendency toward tearout at the corners of the cant, and a rough surface on the cant and formation of some fines. The peripheral-milling used an end-clamped, green slash pine bolt that had been previously shaped to leave a known volume of wood for removal in four successive passes at different feeds per knife. Resulting pulp chips were made at feeds per knife of 1/2, 5/8, 3/4, and 7/8 inch; net specific cutting energy was respectively 0.0026, 0.0024, 0.0023, and 0.0020 hp minute per cubic inch of wood removed. Shear failures caused at the time of chip formation permitted the gross chip to be broken into smaller conventional pulp chips in size and appearance. Both specific-cutting energy and the force normal to the longitudinal axis of the bolt were reduced. Surfaces generated were accurate and smooth. In cutting with a shaping-lathe configuration, rotational speed of the log was variable from 2 through 14 rpm. The cutterhead spindle was fixed while the work piece spindle oscillated under control of the cam to generate the shape of the cant. The specific-cutting energy averaged 0.009 hp minute per cubic inch of wood removed. The configuration produced an accurately sized cant with a superior surface and sharp, well-defined corners. The flakes had dimensions suitable for the manufacture of flakeboards with superior mechanical properties.

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