7 6 FOREST UTILIZATION 



C. Additional parts of high grade saw mills: 



I. "The log haul up" (elevator) consists of a flanged foot 

 wheel and. an inclined trough, on the bottom of which 

 runs a strong endless chain driven by sprocket wheels. 

 The chain has steps (called welds) at intervals of about 

 6 feet. 



The haul up is driven by a separate engine or from the 

 main shaft by double gear wheels. It consumes a great 

 deal of power. 



At the upper end of the haul up, a log flipper "boxes" the 

 logs out of the trough onto the log deck, which is usu- 

 ally inclined toward the carriage. 



On the log deck, the logs are freed from dirt and bark 



by hand. 



II. "The nigger," handled by the sawyer, throws the logs on 

 the carriage and turns them by a boxing movement. 



III. "The hog" is a steel box within which the edgings and 



trimmings are cut into' small slices by very strong 

 knives rapidly rotating. 



IV. "Dust conveyors" convey the output of the hog and the 



sawdust automatically to the boilers. 



D. The edger. 



The boards, falling from the log, are conveyed automatically or 

 by hand to the edger. 

 I. Parts of the edger are : 



(a) One or several circular saws of 12 inches to 28 



inches diameter. 



(b) Feed works, either power or hand driven, consist- 



ing either of a carriage or of feed rolls or of 

 barbed chains by which the boards are fed into 

 the saws. 



(c) Edger table. 

 II. Task of the edger is: 



(a) Removal of defects, knots, bark edge at the side of 



a board. 



(b) Splitting boards into pieces of different quality. 



(c) Rapid sawing to proper width required for special 



purposes. 

 HI. Kinds of edgers. 



(a) Hand feed edger, with one or two saws. 



(b) Power feed edger, usually with a single saw. 



(c) Gang edger. 

 IV. Pointers. 



(a) The distance between the various saws in gang 



edgers is regulated by overhead levers or by 

 hand wheels. 



(b) Several boards can be fed at one time. 



(c) The attendant of the edger must be a lumber in- 



