The Bell System Technical Journal 



July, 1928 



Precision Tool Making for the Manufacture of 

 Telephone Apparatus 



By J. H. KASLEY and F. P. HUTCHISON 



THERE is probably no field of human endeavor in which hand 

 labor has been more completely replaced by labor-saving devices 

 than in the field of manufacturing. The design and employment of 

 special tools together with semi- and full automatic machinery for 

 operating them have reached a high stage of development and are 

 probably more responsible than any other factors for the present age 

 being generally referred to as the industrial age. The notable econo- 

 mies of present day manufacture result no more from the rapid 

 production of parts thus made possible than from the interchange- 

 ability of these parts because of the accuracy with which they have 

 been produced. 



At the foundation of precision manufacture by machine lies the 

 art of tool making. As a result of the impetus given it by the eco- 

 nomic justification underlying the transition from hand labor to 

 mechanical devices, it has grown steadily in importance and in refine- 

 ment. In large measure, it is the art of tool making which insures 

 the interchangeability of product. 



There are probably few industries in which the refinements of the 

 tool making art have been carried further than in the manufacture 

 of telephone apparatus and equipment, especially when handled on a 

 large production basis as by the Western Electric Company. The 

 purpose of this article is to outline some of the refinements of the 

 tool making art as practiced by this Company and to do this, illustra- 

 tive material will be drawn from among the large number of punches 

 and dies used for punch press methods of manufacture. The methods 

 employed and precision necessary in building the tools discussed below 

 can be considered as representative of the high class of workmanship 

 required throughout the Company's tool rooms. 



Punches and Dies 



Tool Making for Telephone Apparatus Manufacture. Briefly, a 

 punch and die comprises a pair of individual tools so constructed 

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