Effects of Roller-Bar Compression and Restraint in Slicing Wood 1-Inch Thick

One-inch-thick slices of clear flat-grained chestnut oak, Douglas-fir, and yellow-poplar were cut at 5 feet per minute using a modified milling machine. Cutting was done at 70? and 200?F., with various amounts of compression and restraint applied by a free-rolling pressure bar 1-1/4 inches in diameter. Physical damage, thickness variation, and forces were measured. Forces as high as 2,180 lbs. per inch of length were observed. In all cases, hot cutting was better than cold. Yellow-poplar cut much better than the other two species and was the only one that could be cut entirely free of physical damage. As compression increased, checks generally decreased on the knife side and increased on the bar side. Increasing restraint had less effect than compression and generally reduced checks on the knife side and had little effect on the bar side. Thickness variation which ranged from 0.005 to 0.190 inch was increased by increasing compression while restraint had little effect. The best cut pieces were relatively smooth with depth of checks from 0 to 1/2 inch and were cupped toward the pressure-bar side of the slice. For evaluation of the strain pattern during cutting, a grid pattern of 10 squares to the inch was cut on one face of each specimen. When heated specimens were required, blocks were preheated in water at 200?F. for 2 hours prior to clamping in the machine. The knife-bar assembly was fastened to the force dynamometer which in turn was fastened to the machine table. A strain-gage type of dynamometer was used to measure the bar-knife forces.

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