In hand forged wrought iron, upsetting means the thickening or shortening of a piece of iron.
When upsetting stock, the heat should be taken just where it needs to be made large. In case the heat spreads over more of the bar than is desired, water should be poured on the part which is to be cooled.
There are different methods of upsetting. Say, for instance, a bar 10 in. long is to be upset on the end. It is heated on that end, then caught in a pair of tongs, holding the piece vertical, and hammered on the cold end while the hot end is on the anvil. This hammering bulges the iron out where it is hot. The piece should be kept straight while upsetting, as it upsets much faster and is not so liable to fracture the grain of the stock.
Another method of upsetting iron is when the piece is held in the tongs, and the metal is driven back with the hand hammer. This method is a good one when the piece needs but little enlarging. For instance, where small stock is to be welded together, it is quicker and easier to keep the bar straight, as the tongs need not be changed; at the same time the scarf can be partly worked out.
Ramming. When bars from 2 ft. to 4 or 5 ft. long are to be upset they are heated on the end and churned up and down on the anvil, the force of the blow enlarging the part heated. Or, in case the bar is to be upset a foot from one end, the bar being long enough to be handled without danger of burning the hands, it is upset by ramming.
Yet another way of upsetting pieces that cannot be rammed or upset on the anvil, owing to parts that must not be hammered on, is to heat the part to be upset in the same manner as described above, then catching it in a strong vise and enlarging the part by striking it with a hand hammer.