CONVERSION OF VALUES OF A STANDARD RULE 



81 



For a 1%-inch saw kerf plus jig-inch shrinkage = j^g = .25, 

 1 



100 X =80 per cent. 



1.25 



Then, 



'""^^S-a"'"^ 



+4.8 per cent. 



The following table will convert values for the International j-inch log rule to 

 products of saw kerfs of other widths, allowing j^-inch shrinkage in each case as 

 for the original rule. 



TABLE XIII 



Conversion of International Rule j-incii Saw Kerf for Other 



Widths of Kerf 



* This per cent applies only to the residual portion of the log after deducting the waste for 

 slabbing and edging. The ratio between the per cents utilized is the basis for correcting for saw 

 kerf. 



Log rules which make no allowance for shrinkage may be adjusted in the same 

 manner by omitting this factor. Table XIV, Page 82. 



Correction for lumber thicker than the standard. For this purpose the same 

 formula as for saw kerf is used, substituting the actual thickness of lumber (0 for 

 1 inch, and using i^ as a constant representing saw kerf. 



Let 1 = standard thickness of lumber; 



/= actual thickness of lumber. 

 Then, 

 1 

 l+K 



t 

 T+K 



= per cent of lumber, minus saw kerf by standard rule; 

 = per cent of lumber, with thickness of t; 



and 



=per cent correction. 



1 

 l+K 



t 



t+K 

 For ^-inch saw kerf the results obtained are given in Table XV, Page 82 (§ 48) : 



