SAWS. 



183 



angled triangle, the shorter side of the triangle or face of the 

 tooth being at right angles, or nearly so, to the line of their 

 insertion on the saw. In English saws the hypotenuse, or 

 back of the teeth, is cut-out in a curve (Fig. 88). Such teeth 





Fig. 87. Oblique triangular teeth. 



Fig. 88. Oblique socket teeth. 



are used only in the case of one-handed saws, or in pit-saws 

 used by woodcutters for sawing timber longitudinally. 



Forest saws which cut both ways require teeth of a different 

 shape. They are always symmetrical, and usually bounded by 





Fig. Xl. Erect dog teeth. 



straight lines : dog teeth, as in Fig. 89 ; curved teeth, as in Fig. 90, 

 the Harz saw 7 ; or are so-called M teeth, Figs. 91 and 92, 

 which cut both ways. American saws have teeth as shown in 

 Figs. 93 and 94, in the latter, dog and M teeth are combined. 



Fig. 91. 



Simple M teeth. 



Fig. 92. 



M IWl 



Fi'_ r . '.I!'.. IJcvellctl American teeth. 



Space must be allowed between the teeth for the escape of 

 the sawdust, which requires four to six times the space of the 

 wood from which it is taken. This is provided by giving the 

 teeth a much greater depth at a b (Fig. 95) than their cutting 



