Shrinkage and oversizes of beech boards

The carried out investigations had a purpose to find out the proportion between the shrinkage of beech-wood determined on the basis of small lab test pieces (3 x 3 x 2 cms) and shrinkage determined on the boards (25, 38, 50 and 76 mm thickness, 110-120 mm width). The beech-wood tested was selected from two regions of different height above sea-level. The results obtained show that the shrinkage determined on the basis of small lab test pieces cannot be taken as a competent for determination of oversizes on the thicknesses or on the widths of boards. The shrinkage determined on the boards is always larger than the shrinkage determined on the small lab test pieces. Consequently, in reality there is required a larger oversize from that which would be determined on the basis of behavior of small test pieces. The difference between theoretically and practically required oversizes are higher by thickness than by width of the boards. The actually required -oversize is increased if also a standard deviation of shrinkage is taken into consideration. Finally, the charts have been made for determining the oversizes for other thicknesses or other moisture contents different from those comprised by investigation.