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BELL SYSTEM TECHNICAL JOURNAL 



of spearing the little solder discs as with the straight wire, the solder is 

 punched in the shape of a horseshoe and squeezed in place on the hook or 

 positioned by tool with the hooked wire in place on the spot. Hooked wire 

 attachments will withstand pulls of the order of three to four pounds before 

 pulling off. Under severe vibrat ion hooked-wire attachments have the same 

 tendencies as straight wires towards breaking away of the wires from the 

 top of the solder cone forming a small crater in the latter. However, the 

 crater does not progress deeply enough into the solder cone to impair their 

 strength or cause failure under ordinary conditions. 



Fig. 13.7 — Examples of headed phosphor-bronze wire. 



The most recent development for wire supports involves the use of headed 

 phosphor-bronze wires as worked out by A. W. Ziegler. In this procedure 

 individual wire lengths are cut and one end upset in a cold heading tool 

 which provides a Uttle cone-shaped head with a base of about 22 mils as 

 shown in Figure 13.7 for 6-mil diameter wires. The head is carefully pre- 

 tinned, leaving a small globule of solder at the end. Depending upon the 

 size of the crystal plate, globules of 1000, 3000 or 7000 cubic mils of solder 

 are used. The attachments are made in a wire soldering tool which attaches 

 the wires to both sides of the plate simultaneously. This tool is illustrated 

 in Figure 13.8. The prepared wires are fed into positioning guides, which 



