investigation the waste of current sawing and offering a new method of sawing based on reverse engineering

this study was accomplished in iran to investigate waste of common log sawing methods and to propose new sawing method. the old methods were performed due to difficulties on carrying logs out of forest. it seems necessary to change old methods due to development of sawmills and forest harvesting plans. the dimensions of wood products were collected to calculate the waste of old sawing methods . the computer software , autocad 14, was used to simulate sawing base on old sizes and nominal sizes and then the volumes of wood products were calculated to estimate the yields for old methods and new methods. the yields of two old sawing methods, double taper sawing and square sawing, were respectively estimated 60.6 percent and 51.9 percent. the waste of resawing to manufacture wood products was estimated 60 percent so that total yield of sawing and resawing was reduced to 33.6 percent. in new method base on reverse engineering nominal sizes of wet lumber thickness were estimated between 1.4 centimeter and 6.7 centimeter by adding contraction and sanding factors to final dimensions of wood products. after sawing logs to nominal thickness and producing lumber with nominal width between 1.4 centimeter and 21.9 centimeter, yield of sawing to manufacture wood products with nominal dimension was estimated 75.3 percent by this study, so this new method is offered as a best choice with ability to increase yield up to 41.6 percent.