Sawmill men will find that little surmise or conjecture is involved in 

 determining the board foot-cubic foot ratio* This ratio can be computed 

 very easily by comparing the yield of lumber with the cubage of the logs. 

 The number of board feet of lumber per cubic foot of log gives the board 

 foot-cubic foot ratio 9 just as the number of board feet of lumber per 

 board foot log scale gives the overrun (percent) ratio « Typical ratios 

 appear in table 4. 



Table 4» Board foot-cubic foot ratios and overrun ratios" - 



Location 





: Board foot—: 



Over— s 







of 



; Species 



i cubic foot % 



run : 



Log rule 



sawmill 





: ratio : 



ratio : 



used 





Montana 



West white pine 



7.30 



1.21 



Scribe 



Dec.C 



Arizona 



Ponderosa pine 



7.41 



1,08 



Do 





Montana 



Do 



7.78 



1,21 



Do 





Oregon 



Do 



7*74 



1*10 



Do 





Oregon 



Do 



7,56 



1*02 



Do 





3 Carolina 



Loblolly pine 



5,50 



1,27 



Doyle 





Montana 



Engelmann spruce 



6o94 



1.09 



Scribo 



Dec.C 



Oregon 



Douglas fir 



7,69 



1.14 



Do 





Oregon 



Do 



7,43 





Do 





Virginia 



Hardwoods 



5,99 



1,30 



Doyle 





Virginia 



Do 



6o30 



looa 



Do 





Wisconsin 



Do 



6,68 



1J.6 



Scrib e 



Dec* C 



2/ By the "board foot-cubic foot" ratio is meant the number of board 

 feet of rough-green lumber produced per cubic foot of log„ By the 

 "overrun ratio" is meant the number of board feet of rough-green 

 lumber produced per board foot log scale a 



As table 4 shows, the board foot-cubic foot ratio is not the same for 

 all mills and runs of timber any more than overrun percent is the same 

 in all instances o In fact, the board foot-cubic foot ratio depends 

 upon the same factors that influence overrun percent a 



Converting factors for products other than lumber can be worked out 

 just as simply* Many of the measures used in the timber industry, 

 such as the cord (128 stacked cubic feet) and the unit (200 cubic 

 feet, gross volume), are companions of the cubic foot. Their 

 relation;; to solid cubic feet for some common products is given in 

 table 5« 



-13- 



