66 FOREST UTILIZATION 



A short blade yields the finest .work, since it can 

 be spanned more tightly. 



The gauge along the back should be finer than 

 the gauge along the cutting line. 



The saw can cut any thickness of trees. 



The saw cuts only by the down stroke while the 

 log is moved against the saw during the up 

 stroke. 



The saw is spanned in a guide frame and is given 

 as many inches inclination toward the log as 

 the feed of the carriage per stroke amounts to. 

 If the saw were not inclined all the work would 

 be done by the lowest teeth. 



The usual set is still the spring set and not the 

 swage set, although the latter is sure to be su- 

 perior. 



Usually the ends of the boards are not sawn 

 through but are held together by the "comb," 

 which is finally split with the axe. 



In filing mill saws, obtain sufficient pitch of teeth 

 to prevent saw from kicking out of the cut. Too 

 much pitch, however, causes shattering. 



Gullets must be kept carefully rounded. 



(b) Gang saws. They are used in large mills for in- 



ferior logs. 

 The best make is Wickes Bros.,' Saginaw, Mich. 



Enormous stone foundations are required. 

 The saw frame has an oscillating motion which 



presents the saw to the cut in an easy raking 



sweep, forcing each tooth to do its full share 



of the work. 

 Gang saws are not fed from a carriage. The logs 



are run through feed rolls, feeding the logs, into 



the saws. 

 Blades are 6 to 10 inches wide and of 8 to 16 



gauge. 

 Horsepower required is said to be for friction, 



3 horsepower ; for first blade 4 horsepower, and 



for every additional blade l /2 horsepower more. 

 Where log heaps (up to 12 logs) are run through 



the gang saw, the logs are slabbed by a "rosser" 



or "log siding machine," so that the logs can 



be placed one upon another. 



(c) Horizontal frame saw. It is used to cut fine 



veneers and valuable timber. Its advantage lies 

 in the fact that very little weight rests on the 

 saw, that the saw can cut on both trips (to and 



