54 THE MEASUREMENT OF LOGS— BOARD-FOOT CONTENTS 

 K 



T+K 



T 

 T+K 



= per cent deduction for saw kerf, 

 = per cent of log utilized as lumber. 



Efforts to account for the exact per cent of waste in sawdust have been made, 

 by including, first the saw kerf required for ripping or edging one edge, as shown 

 in Fig. 8, 1 and second, the additional saw kerf for the first slab. But neither method 

 is complete, since boards are edged when necessary on both edges. The best method 

 is probably to include this extra saw kerf, together with the edgings, in the waste 

 due to slabbing, leaving the sawdust as a straight per cent of volume. 



Shrinkage. Where shrinkage is considered, or where lumber must be 

 sawed a trifle full, the extra thickness which is not measured in the 

 green lumber constitutes a waste exactly similar to saw kerf, and can be 

 added to the latter factor in the formula before calculating the per 

 cent of reduction. 



For instance, if a log rule is intended to measure the output of 1-inch 

 lumber after seasoning, and the average shrinkage on inch boards ia 

 rg-inch, and saw kerf |-inch, the per cent of waste in small logs is 



ij i_ 1875 



i+i+A = n875 =15 - 8percent - 



1 By the inclusion of one edge, the formula for sawdust would be: 

 Volume of unit (W+K)(T+K), 



Saw kerf K(W+T+K), 



Per cent of waste J^E±I+?1 

 Per cent of waste {W+K)(T+K) - 



H. E. McKenzie, Bui. 5, California State Board of Forestry, Sacramento, Cal., 

 1915. 



By inclusion of the extra saw kerf but not of the cut for edging. 



Number of cuts =N, 



Average saw kerf per board = if +— ■, 



rr 



Volume of unit =T+K+ 



Per cent of waste 



N' 



r+ *4 



C. M. Hilton, Bangor, Me., 1920. 



