12 BULLETIN 440, U. S. DEPAETMENT OF AGRICULTURE. 



OVERRUN.i 



With average timber and a normal lumber product, the overrun 

 at a mill employing an inserted tooth circular saw is negligible if not 

 lacking. A solid tooth circular saw does a trifle better, showing a 

 possible average overrun of 2 or 3 per cent. The figures obtained 

 at a number of efficient band miUs range from 5 to 8 per cent, the 

 most common being 6 per cent or a fraction over. A short mill tally 

 at a band mill sawing pine timber from a National Forest sale in 

 the southern Sierras showed an overrun of 5 per cent. 



A mill taUy of 4,190 logs made during the summer of 1914 at a 

 representative single band mill in the northern Sierras gave the fol- 

 lowing average overrun of the decimal C scale: Sugar pine, 7 per 

 cent; yellow pine, 6.9 per cent; Douglas fir, 10.3 per cent; white 

 fir, 2.5 per cent; incense cedar, 15.6 per cent. These percentages 

 are perhaps shghtly above the average on account of the manufac- 

 ture of sawed ties from many top logs. A second tally of 4,890 logs 

 at another single band mill during 1914 gave the foUowing overrun: 

 Sugar pine, 2.6 per cent; yellow pine, 0.7 per cent; Douglas fir, 8.1 

 per cent; white fir, 1.1 per cent; incense cedar, 16.6 per cent. Most 

 of the oveiTun occurs in the logs of poorer quality. 



TIMBER QUALITY. 



The proportion of the various grades produced depends not only 

 upon the quality of the timber but also upon the efficiency of the 

 operation, the size of the miU, and the facihties for marketing lum- 

 ber. Inefficient operations do not cut as high a proportion of the 

 better grades as efficient ones. Small mills without a marketing 

 organization do not take as much care in separating grades, and fre- 

 quently put all lower grades into box. 



In speaking of the quality of a tract of timber it is customary to 

 say that it will produce a certain per cent of uppers, meaning No. 2 

 shop and better. The poorer yellow and Jeffrey pine stands in east- 

 ern California produce about 20 per cent uppers; better stands pro- 

 duce from 25 to 30 per cent. Normal mixed stands of sugar pine, 

 yellow pine, Douglas fir, white fir, and incense cedar produce from 

 25 to 3 1 per cent. In sugar and yellow pine stands the pine commonly 

 cuts from 32 to 45 per cent uppers^ yellow pine alone from 30 to 45 

 per cent, and sugar pine from 35 to 55 per cent. 



A comparison of the lumber grades produced from sugar and 

 yellow pine may be made from Table 2, which shows the results of 

 two mill tallies made by the Forest Service during the season of 1914. 

 The first of these was for 2,230 logs at a single-band mill in the south- 

 ern part of the Shasta National Forest, and the second for 2,490 logs 



1 This information on mill overrun of log scale is derived from a comparison of the figures of scalers and 

 tallymen at several representative mills. The log scale is commonly made by the Spalding rule, which 

 is somewhat similar to the decimal C rule used on National Forest timber sales. Overrun is greater in small 

 or very large logs; less with saws of heavy kerf, and greater when thick planks or timbers are sawed. 



