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Chapter 22 



M 149 143 

 Figure 22-63. — Manufacturing system, termed SDR, designed to control crook in hard- 

 wood studs. Logs are live-sawn into flitches; these flitches are dried and then ripped 

 to yield studs. (Drawing after Harpole et al. 1981.) 



Conventionally sawn yellow-poplar studs, even when dried at high tempera- 

 tures, had average crook of nearly Vs-inch. 



Maeglin et al. (1981) found that small yellow-poplar sawlogs converted to 

 studs by the SDR process yielded 84 percent more product value than if sawn 

 into 4/4 boards. See table 22-27 for volume yields, and table 22-28 for grade 

 yields. 



Table 22-27 — Lumber yields from 10 8-foot-long yellow-poplar logs sawn by three 

 methods to two thicknesses (Maeglin et al. 1981)' 



Statistic 7/4 SDR^ 7/4 CON^ 4/4 boards'^ 



Log diameter inside bark at small end, inches 7.5 7.5 7.4 



Log volume, cubic feet 26 26 25 



Scribner Decimal C volume, board feet 127 128 124 



Nominal lumber tally, board feet 218^ 215^ 156 



Lumber recovery factor 8.5 8.5 6.2 



'Data based on logs sampled from four states: North Carolina, Tennessee, Virginia, and West 

 Virginia. 



SDR means live sawing, drying, ripping. Data based on 40 logs per state. 

 ^CON means centered-cant sawing. Data based on 40 logs per state. 



"^Boards were cut using the cant method and full taper sawing; logs were rotated to recover highest 

 grade possible. Data based on 10 logs per state. 



^Of the total volume of SDR studs, 62.6 percent were 2 by 4, 21 .4 percent 2 by 3, and 16 percent 2 

 by 2 inches. 



^Of the total CON studs, 81.9 percent were 2 by 4, 14 percent 2 by 3, and 4.1 percent 2 by 2 

 inches. 



