MANUFACTURING AND CONDITIONING 



153 



Lumber has been produced chiefly from our great sawmills, some 

 cutting as much as 200,000 to 1,000,000 b.f. per day each, in two 

 shifts. Saw logs pass through a very interesting procedure to convert 

 them from round shapes into square and flat forms used in commerce 

 and industry. On delivery from logging operations in the woods, logs 

 are generally stored in a log pond, from which they are elevated to 

 the second floor of the sawmills by a continuous chain known as a 

 jack ladder. They are rolled down a log deck to a saw carriage, on 

 which they are fastened against knees and headblocks by a setter 



FIG. 88. Typical small portable sawmill cutting about 5000 b.f. per day with 

 5 men. On the left is shown the log deck, saw carriage, and circular saw. Large 

 pile of saw dust in foreground. On the right is tractor which furnishes power 

 for the sawmill. Much lumber is made throughout the East, Lake States and 

 South by these small sawmills. 



and his assistant. The carriage conveys the logs through the saw, 

 of circular type as used in most of the small mills or a band saw. 



Most of our lumber is sawed by large band saws. These are con- 

 tinuous bands of steel which travel at the rate of about 900 feet per 

 minute and make successive cuts of lumber or timber from the log. 

 The lumber is passed through an edger, which trims off bark, knots, 

 or other defects to make the two edges parallel. Then it goes to the 

 trimmer saws which cut off the pieces at the desired lengths. From 

 the trimmer saw, the lumber passes on to the grading or sorting table 



