PRECISION TOOL MAKING 



383 



fit together within an overall limit of + .001 — .000 in., that the 

 punches and perforators must be accurately centered in the die 

 openings with a clearance all around for the punches of .0003 in. to 



Fig. 8 — Second operation punch and die for perforating holes in rack. 



.0005 in. and for the perforators about .0001 in., it is apparent why, 

 with the possibility of the errors being accumulative, each individual 

 section must be made very accurately, the majority not exceeding a 



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Fig. 9 — Phosphor bronze rack for panel dial equipment. 



limit of ± .00001 in. In addition, the slot in the die holder which 

 holds the die, shedder, and punch plate sections, is made to almost 

 exact dimensions and must have its sides parallel with each other and 

 perpendicular to the bottom surface. 



