Measures and yields of products and residues 33 13 



TIES AND TIMBERS 



Sizes and specifications for crossties and switchties are explained in section 

 22-10 and table 22-20. The size of timber obtainable from a log is related to log 

 diameter, sweep, and species (table 22-18, figs. 22-51, 22-52). Often low-grade 

 logs will have a greater yield, both in terms of board feet and dollar value, when 

 sawn for timber and lumber instead of just lumber (tables 27-125 and 22-17; fig. 

 22-50). Table 22-44 gives the yield of lumber and residues from 1,000 bd ft 

 Doyle when red oak logs 13 inches in diameter and 8 feet long are cut for 

 crossties and lumber. 



Low-grade hardwoods, particularly logging residues and thinnings, can also 

 be a source of mine timbers. Timson (1978) found that after a sawlog harvest, 44 

 percent of the logging residues measuring at least 4 feet long and 4 inches in 

 diameter outside bark was suitable for mine timber production. Minimum char- 

 acteristics of roundwood suitable for manufacturing sawn mine timbers and 

 round and split props are discussed in section 22-10, table 22-25, and figure 22- 

 62. Species preference is also covered in section 22-10. 



PARALLEL-LAMINATED THICK VENEER 



Subsection PARALLEL LAMINATED VENEER in section 22-10 (page 2705) 

 lists literature related to the subject. Section 28-2 contains an economic analysis of a 

 small scale operation to produce sawn veneer for parallel lamination into high- 

 price furniture, and section 28-21 analyzes the economic feasibility of producing 

 hardwood laminated-veneer flanges for fabrication with flakeboard webs into 

 long-span I-beam joists. Both accounts estimate yield, but the literature contains 

 little experimentally-derived data on yield of thick-peeled hardwood veneer. 



In a study with southern pine (Schaffer et al. 1972), 4-foot-long bolts cut at 

 thicknesses of 0.43 1 or 0.500 averaged 66.6 percent yield of green veneer. Yield 

 increased with bolt diameter (figure 27-21). Allowing for losses during drying 

 and subsequent manufacturing, the dry product yield from logs 12 to 18 inches in 

 diameter should average about 60 percent — about l-Vi times the yield typically 

 obtained by sawing. 



27-3 RESIDUES 



LOGGING RESIDUES 



In general, an upland hardwood tree has about 50 percent of its complete dry 

 weight in the bark-free stem, 30 to 35 percent in tops (with foliage) and stem- 

 bark, and 15 to 20 percent in the central stump-root system. These proportions 

 vary significantly among species and between trees of a species as discussed at 

 length in section 16-1 (e.g., see tables 16-2 and 16-10). Table 16-2, containing 



