WIRE-MAKING. 



797 



weight is still further reduced; 50 to 200 pounds 

 at No. 12 becomes 50 to 80 pound coils at No. 20, 

 30 pounds at No. 25, 20 pounds at No. 30, and 5 

 to 15 pounds at smaller sizes. Indications are 

 that still larger coils of rods will be rolled in 

 1902, although it will necessitate larger and more 

 powerful machinery in the rod and wire mill at 

 all points where the rod or wire is coiled or lifted, 

 in the wire-drawing, annealing, cleaning, and 

 tempering rooms. For the users, the lengths are 

 satisfactory except in special instances. For the 

 fine steel wire used for kite-flying, and for deep- 

 sea sounding, the United States Government serv- 

 ice require an unbroken length of 5 miles, or 50- 

 pound coils, while the factories seldom make more 

 than 10- or 15-pound coils at the small sizes 

 wanted. For the strong steel wire used for sus- 

 pension bridges, an unbroken length of wire is 

 required of 3,000 to 4,000 feet. No. 6 to No. 9 

 wire has been chiefly used, and a 250-pound coil 

 of rods would make the lengths required. This 

 the wire-makers could do. Suggestions have been 

 made to use ^-inch wire of the same length, which 

 would require a 600-pound coil of rod, making the 

 usual allowance for waste and breakage in manu- 



down to ^-inch diameter wire. For No. 4 and 

 No. 5 rods the dies are 7 to 15 pounds in weight. 

 For Nos. 5 to 10 wire a 5-pound die is strong 

 enough, and for Nos. 12 to 20 a 2J- or 3-pound 

 die. It is the custom in some mills to use cast- 

 iron dies for larger sizes than No. 12, and steel 

 dies for No. 12 and finer. For sizes smaller than 

 No. 20 the dies weigh 1 or 2 pounds. Some of 

 the 3-pound dies have as many as 10 holes. For 

 fine wire special rectangular dies and flat draw- 

 plates are also used. 



For drawing wire on continuous machines it 

 is possible to use an ordinary die for Nos. 20 to 

 30, but frequently a special die is made by cut- 

 ting a section off a larger die, to make a square 

 or round plate with but one hole. For sizes 

 smaller than No. 30 a thin plate of steel may be 

 used, inch or less in diameter, with one hole. 

 For No. 32 and smaller diamnd, draw-plates are 

 used. Steel dies can be made as fine as No. 36; 

 but by the ordinary method of drilling the hole 

 the slender drill at this size is apt to bend in 

 drilling and spoil the exactness in the size of the 

 hole. Steel wire can be drawn in diamonds as 

 fine as 0.002 inch for commercial use. Smaller 



TANDEM CONTINUOUS ROD-DRAWING MACHINE. 



Floor-space, 14 feet by 2 feet 6 inches. 



facturing. To make such large coils of cable-wire 

 would require the special large machinery re- 

 ferred to for handling. 



The steel wires for a suspension-bridge cable 

 must be one continuous length, without weld, 

 splice, or joint. Copper wire is easily welded or 

 brazed. So also are the low-carbon steel wires. 

 The high-carbon steels, 0.40 to 0.75, are brazed 

 and used successfully to make long lengths of 

 wire for stranded wire-rope, but would not be 

 considered safe to use in a suspension-bridge 

 cable, where the wires are laid parallel, and there- 

 fore each wire must be from an unbroken coil of 

 rod. 



Steel dies may be used for drawing all sizes of 

 steel wire, but for large sizes cast-iron 'dies are 

 commonly used. The largest dies weigh 30 

 pounds, are rectangular, and are pierced with 

 4 to 6 holes. These are used for drawing 1-inch 



wire than this has been drawn only in very small 

 quantities. 



The diamonds used for draw-plates are not 

 equal in value to those used for jewels. What is 

 wanted for a draw-plate is a flat diamond -^ inch 

 thick, and J to f inch diameter, either round, 

 square, or triangular, but any shape can be used 

 than can be drilled without breaking. For this 

 use the slabs, cleavages, and endings which are 

 made by the diamond-cutter in shaping large dia- 

 monds make the best draw-plates. They can be 

 used unpolished or polished, are of the right shape 

 and size, and good in quality. African diamonds 

 are used, although the Brazilian diamond, being 

 harder, makes a better draw-plate; but Brazilian 

 clippings are difficult to obtain. The natural 

 stone is preferred if it can be obtained, and dia- 

 monds that are considered as blemished by reason 

 of defective color, flaws, or foreign substances em- 



