Fig. 106. Fig. 107.
The rough forging should always be made a little larger than the finished tongs; finishing it to size when the handle is welded on. When both jaws are forged, they are cut in the center and the handles are welded on. When the handles are well upset and scarfed, the shanks of the jaws are drawn to equal size. Care must be taken in having the scarfed ends equal in size or a poor weld will result. The handles at the weld are drawn square with the corners tapered off. The jaws are now drawn and fitted to size. Notice that the lip tapers on the edge, also on the flat part. A small flute is fullered lengthways on the inside of the lip so that round as well as flat iron may be held. The hole is next punched thru the eye with a hand punch. A piece of ⅜-in. rod of soft steel is cut to the proper length and used for a rivet. It is heated and inserted into the holes in the jaws and hammered on both sides with hard blows. The jaws of the tongs are now heated red and worked back and forth to loosen the rivet in the eye. The jaws are fitted to the size of the stock they are to handle as in [Figure 107]. The regular stock rivets should not be used in tongs. The ⅜-in. round piece headed from both sides fits the holes thru the eye best.
Fig. 108.
In making tongs to hold a larger piece of stock, the square bar should have an offset. The jaws should then be forged as in [Figure 108]. Notice where the hammer strikes the bar to offset it.
In forging tongs, the handles should be welded to the jaws to give practice in welding.
Pig Iron.
Pig iron is made by smelting the iron ore in a blast furnace. The ore is charged in a furnace mixed with lime stone as a flux, and melted by using coke or coal as fuel. The resulting metal is called pig iron. It contains from three to five per cent of carbon, two to four per cent of silicon and various small amounts of sulphur, phosphorus and manganese.