Measures and yields of products and residues 3289 



where: 



W = weight of the load, pounds 



N = number of pieces on the load, with logs less than 20 feet long 

 counted as a half log 



Adams (1976) proposed a method of weight scaling that would systematically 

 adjust for changes in timber size and species composition in the truckloads of 

 mixed hardwood saw logs delivered to a mill. The steps in his adjusting factor 

 method are as follows: 



1. Weigh and stick-scale (check-scale) the first 10 loads. Add the weights 

 of the 10 loads; add the volumes of the 10 loads. 



2. Divide total weight of the 10 loads by total volume of the 10 loads to get 

 a weight/volume conversion factor. 



3. As the next 20 loads come in, check-scale one load at random, and 

 weigh-scale the other 19 using the conversion factor from step 2. 



4. Add the newest check-scaled load to and delete the oldest check-scaled 

 load from the 10-load tallies for weight and volume. 



5. Return to step 2 to compute a new, adjusted conversion factor, and 

 continue the process. 



Any log rule can be used with the adjusting factor system, and a test of the 

 method indicated that over a period of time the weight-scaled volume should 

 average within 3.5 percent of the actual volume. The adjusting factor method, 

 however, does not include a way of determining log quality; so mills that 

 purchase logs by grade cannot use it. 



Several studies have addressed the problem of scaling multiple products by 

 weight. Guttenberg and Fasick (1973) developed a computer program for simul- 

 taneously estimating the saw log and pulpwood volumes on each truckload. 

 Fasick et al. (1974) developed equations for predicting volume and weight of 

 veneer logs, saw logs, and pulpwood based on net truckload weight and number 

 of trees per load; their equations were based on 10 random samples of 200 loads 

 each of tree-length southern pine. A manual that explains the computer pro- 

 grams available to produce multiproduct weight conversion tables from sample 

 loads of tree-length material is available from the Southeastern Forest Experi- 

 ment Station, Asheville, N.C. (Tyre et al. 1973) 



Log weight to board feet lumber scale. — This conversion can be accom- 

 plished indirectly by first converting log weight to log scale as described in the 

 foregoing paragraphs and then computing the overrun. 



English units to metric units. — The American forestry industry has been 

 gradually moving toward the adoption of standardized international units of 

 measure. Table 27-154 gives metric equivalents for the most common units used 

 in forestry. For ease in locating and using this table, it has been placed last 

 among all the tables in chapter 27. 



