1132 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1953 



used in such small quantities that they are replenished by hand. Copper, 

 however, is plated out of each machine at the rate of 900 pounds per 

 eight-hour shift. Copper shot added to replenish this plate-out from the 

 cells must be spread out evenly over a cell area of more than 500 sq.ft. 

 extending 280 ft. along the machine. When this is done, the average 

 depth of the material added is less than Ko"- As a quality control on 

 the copper plate, the anode-to-cathode spacing in the cells (copper shot 

 layer-to-wire spacing) is not permitted to vary from the specified spacing 

 by more that 25 per cent at any spot on the cell surface and the average 

 must not exceed 15 per cent. Shot must be added at least once every 

 eight hours to meet this requirement, and the addition must obviously 

 be made while the wires are running. It would be impracticable to do 

 this job manually in any reasonable time and with any assurance that 

 the quality of the electroformed copper deposit would not be impaired 

 during the addition. 



Copper shot is, therefore, added to the cells with a mechanical distri- 

 butor which automatically sprinkles the shot into the cells uniformly 

 while the machine is running. It is essentially a hopper mounted on a 

 motor driven carriage which travels on the two upper rails of the acid 

 leg of the machine, the bottom of the hopper being fitted with a rubber 

 surfaced feeder roll and a stripper comb which releases from the hopper a 

 controlled amount of material. The feeder roll is also motor driven and 

 timed relative to the travel speed of the carriage. Both carriage and feeder 

 roll are operated from rubber grips so that the machine operator may 

 stop the distributor wherever he wishes or by-pass any cell if he so desires. 

 To prevent the spillage of shot on the contact rolls between the cells, 

 block-out cams are placed on one rail to operate a cut-out switch which 

 stops the feeder roll while the distributor passes over the contact roll 

 space between cells. The speed of the feeder roll can be varied, and the 

 height of the stripper comb can be changed to vary the amount of shot 

 released per foot of distributor travel. A feed run of the distributor re- 

 quires an operator's attendance and takes about twelve minutes to dis- 

 charge shot to the entire acid copper plating line. The distributor returns 

 to its starting point automatically when the feed-run has been completed. 

 The feeder roll is inoperative while the distributor is returning. Power 

 is supplied to the distributor through trolley operating in fully 

 gurarded feed rail running overhead and parallel to the plating line. 



Copper shot is added to the distributor hopper with tilting bucket on 

 a monorail hoist. The bucket is filled in the raw material storage area on 

 the main floor, raised with an electric hoist to the plating deck and moved 

 on monorail track to dumping position over the distributor hopper. 



