PATTERN MAKING 



Fig. 162. 



tributed as to give the greatest possible strength to the rim. 

 In the present case, our pattern is so small that it is only 

 necessary to use a thin board, ^ inch in thickness for each half of 

 the web. After sawing to 6| inches in diameter, -J inch for turn- 

 ing, a block ^ inch in thickness is glued on the center of each to 

 form the hub; and six segments 1^ 

 inches wide and -| inch in thickness, 

 are glued around on the outer surface 

 of each to form the rim and groove, 

 as shown in Fig. 162. 



Care must be taken to place the 

 segments so that the grain of the 

 web will be crossed by two of the 

 segments as shown in the drawings. 



On the second half b of the pattern, a thin circular block \ 

 inch in thickness is glued on the inside opposite to the hub block, 

 to form the projection (^ inch) which will keep the two halves of 

 the pattern in alignment, as shown in the cross-sectional drawing 

 in Fig. 159. Having glued up the stock as described, and as shown 

 in Fig. 162, the outside must be planed to a level surface, or so that 

 the six segments forming the rim and the center hub block will be 

 in the same plane. 



The half pattern is now screwed 011 the screw chuck of the 

 lathe as illustrated in Fig. 163, and the inside, or the parting face 

 c, is turned perfectly straight and true. The edge 

 is turned down to 6 inches in diameter, and the 

 quartered circle shown by the dotted lines is 

 carefully shaped. A template, made as shown at 

 <7, will assist greatly at this stage of the work. A 

 recess is turned at the center, and in the face of 

 Pig. 163. a, Fig. 159, 1| inches in diameter and inch 



deep, to receive the corresponding projection on the half pattern b 

 which is to keep the two halves in alignment. 



The half pattern a, is now removed from the screw chuck, and 

 the second half b is screwed on and turned in the same manner 

 except that the central projection is carefully turned to, fit in the 

 recess in a. 





Before removing b from the chuck, test by trying the second 



