2564 Chapter 22 



22-3 LUMBER, MILLWORK, FLOORING, AND DIMEN- 

 SION STOCK 



LUMBER 



Because the oaks predominate on southern pine sites, perhaps half the lumber 

 volume sawn is oak. Other species cut in major quantities from pine sites for 

 lumber include sweetgum, yellow-poplar, black tupelo, and red maple. Less 

 hickory and post oak lumber volumes are cut than tree volumes would suggest; 

 hickory lumber markets are limited, and much of the post oak is of low quality. 



Data on lumber production from hardwoods growing on southern pine sites 

 are not available, but total hardwood lumber production in the South has been 

 declining slowly (fig. 29-15B bottom). 



Sawmills cutting high-quality eastern hardwood trees derive most of their 

 profits from random-length, random- width 4/4 to 8/4 lumber sawn and graded 

 according to rules of the National Hardwood Lumber Association (1978). Mill- 

 work, flooring, and dimension stock for furniture are manufactured from such 

 lumber. Because hardwoods growing on southern pine sites are small in diame- 

 ter and frequently have short, crooked or defective stems, the yield of the upper 

 commercial grades in desired lumber lengths and widths is frequently too low to 

 support a conventional sawing operation. 



The lumber proportion sawn in each grade, as graded by National Hardwood 

 Lumber Association rules, is related to log grades (tables 12-11 through 12-33) 

 and tree grades (tables 12-34 and 12-40). 



Sawmills appropriate for high-quality, long hardwood logs are described in 

 section 18-10. Chipping headrigs particularly suited to hardwoods are discussed 

 in section 18-9. For conversion of short small logs see section 18-11. 



Time to saw a thousand board feet of lumber depends on mill equipment as 

 well as log diameter, length, and quality (tables 18-54 and 18-55). 



Lumber yields. — Because lumber recovery factors (board feet recovered per 

 cubic foot of log) are generally less than 7 in hardwood sawmills, volumetric 

 recovery of rough green lumber, as a percentage of green log volume, is general- 

 ly less than 50 percent (figs. 18-112 and 22-1). Lumber yield is related to 

 species, sawing accuracy, board thickness, and saw kerf as discussed in the text 

 accompanying figure 18-112 and tables 18-57 through 18-62. 



Lumber recovery factors in hardwood mills are less than in softwood mills 

 partly because hardwood lumber is cut thicker than softwood lumber. Rough dry 

 hardwood lumber can be only slightly less than 1 inch thick to yield moderately 

 long cuttings planed on two sides to a thickness of 13/16-inch; rough dry 

 thickness of panels should be slightly over 1 inch to plane to 13/16-inch. Green 

 4/4 red oak lumber shoud be '/8-inch thicker than required rough size to allow for 

 shrinkage (Freese et al. 1976). Hardwood 4/4 lumber must therefore be cut about 

 l-'/s inches thick, whereas 4/4 softwood lumber is frequently sawn only 15/16- 

 inch thick. 



