PATTERN MAKING 



131 



and more accurate lines will be the result. A coat of shellac 

 brushed over the ends and faces of the blocks, if sand-papered smooth 

 after being allowed to dry, will greatly assist in laying out the 

 teeth, hardening the surface, and enabling sharper lines to be 

 drawn. A template must next be made of the exact form of the 

 tooth required. This will always be given full size in the detail 

 drawings furnished to the pattern maker. 



Should the wheel be of small diameter the template may be 

 laid out and cut on the end of a long strip of zinc, but it is better 

 to fasten the template to the end of a wooden bar, as shown in 

 Fig. 242 a narrow slot having been cut through the back end 

 of the zinc to allow of exact adjustment to the diameter of the 

 wheel. 



This wooden bar is hung centrally on a peg or dowel which 

 must be placed exactly in the center of the hub. For this purpose 



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it is customary to use a block of wood as a temporary hub, the 

 center of which may be easily found from the periphery of the 

 blocks by the dividers. A very slight, sharp notch is made in the 

 exact center of the end of the tooth template, which must be radial 

 to the hole in the opposite end of the bar on which the template 

 revolves. This notch is shown in Fig. 242. 



To use the template, place it over the center pin arid bring the 

 notch exactly in line with one of the spacing lines on the outside 

 of a block and with a very sharp pointed awl mark the tooth on the 

 end of the block. Then swing the template to the next line and 

 mark as before, continuing the process until a tooth has been laid 

 out on the end of each block. The wheel is now turned over and 

 the same process repeated on the other side. It will be readily 

 seen that if the spacing lines have been squared across the face 



