Blocks for upsetting or thickening small work are placed on the ground in some convenient place, and are capable of being easily moved about. Blocks for upsetting large work that is short are adapted to steam-hammer anvils.

Upsetting-blocks are useful for shaping ends of keys, gibs, bolts, bosses of connecting-rods, lever-bosses, joint-bosses, T-ends, and cones. The simplest class of such blocks consist of thick heavy cubic lumps of iron or steel, having flat tops, resembling Fig. 264. These are moved about to various places, or fixed in the earth, so that the upper sides shall be level with the floor, or a foot above it; and, for some purposes, a foot below the floor, the particular height depending on the length of the work to be upset.

To upset a short rod, or bar, by means of a flat-face block, shown by Fig. 264, the work may be placed with one end upwards and the other end on the block; and while thus held with tongs, or porter, a few sledge-hammers are used by two or three men, who hammer the upper end; but when the piece is too long to be thus hammered, the hammers are superseded by the piece of work which is to be upset, because it is made to hammer itself. This is effected by standing the work upright upon the block, lifting the work up and letting it fall. To do this conveniently, the work is heated to nearly welding, and stood upon the block; three or four men then stand around, with the work in the midst, and each man grips a part of the work, and all lift at the same time, until the lower extremity of the piece is a foot or two above the block, at which time all the men let the work fall, and as nearly as convenient in the vertical direction. After one blow given in this manner, the work is again lifted up, and let down as before; and the process is continued until the metal is too cold for further thickening, or until the piece is thick enough, which may be at the first upsetting.

Upsetting by this means is named jumping, and the plan is more suited to thick rods or bars than to thin ones; rods five inches thick are easily thickened by such means, when a band having one or two handles is bolted to the work. Such handles admit a number of men to lift, without hindering each other through being too close together. By jumping, a joint boss can be formed in the mid part of a rod or lever, or near one end; and the boss may be solid or with a hole. If a round hole is wanted, a narrow slit, or slot, may be punched at the place of the intended round hole, and the opening is afterwards made circular by jumping.

When it happens that a great number of pieces are to be upset in this manner, a guide is fixed near the middle of the block face, to maintain the work in the vertical position while being lifted and let fall.

Several sorts of work require to be upset after the extremities are smoothly finished. For work of this character the upseting blocks are made of lead, or, if of iron, a recess is formed into the top of the block that it may hold a thick block of lead, upon which the work is stood instead of iron. After this lead block is become too much damaged by use, it is taken out and melted, with more lead added to the old block; it is next poured into the recess, and is again used for upsetting as before.