WOODCUTTERS 1 M PL EM ENTS. 



^07 



results as shown by the "Nonpareil" saw. Triangular teeth 

 should he f inch high and h inch wide. The spacing between the 

 teeth should be double the width of the teeth, and this suffices 

 for coniferous as well as broad-leaved wood. Wider spacing 

 than this, by reducing the number of teeth, impairs the efficiency 

 of the saw. The slit made in a piece of wood by a saw is termed 

 the kerf. 



The teeth are sharpened with a triangular file (better with a 

 two-faced one) and this should be done until the sides of the teeth 

 which meet the wood are as sharp as knives. Saws which work 



Fig. 89. 



J 



A 



both ways must have their teeth sharpened on both sides. As 

 all forest saws are set, the stroke of the file must be always, as in 

 fig. 89, on the inner side of the teeth. 



When a saw has been properly sharpened, the tops of the 

 teeth must not project above a general 

 line, or the projecting ones will be 

 broken. A good saw in constant use 

 will require sharpening only every five 

 or six days. 



It is highly important that the teeth 

 should retain their proper shape, whilst 

 constant use of the saw and frequent 

 and unskilful sharpening gradually 

 alter it. Messrs. Dominicus & Sou, 



of Remscheid, have introduced perforated saw-blades by which 

 this defect may be remedied. Fig. 90 shows how this is done, 

 and how the teeth drawn successively on the blade below the 

 original set, can be filed down to gradually by the workmen, as the 



Fi.:. 91. 



original teeth become worn-out. Fig. 91 shows how the per- 

 forations are made in a straight cross-cut saw. 



