In direct distinction from the drawing out of the point of the staple just described is the upsetting of the head of a bolt. Drawing out or drawing down may be defined as the reducing of a bar of metal to a smaller diameter or smaller cross-sectional area. Upsetting is the reverse of drawing out and "consists of making a thin bar of iron into a thick one," either for a whole or a portion of its length. To form the head of an ordinary bolt make the width between the parallel sides equal to 1½ times the diameter of the bolt, plus 1/8- inch. The depth of the head is equal to one-half of the width of the bead. Thus, the dimensions of the head of a | inch bolt are .75 X 1.5 + .125 = 1.25 - 1¼ inches for the length of the side and 1¼ ÷ 8 = 5/8 inch for the depth of the head. The cubic contents of such a head is therefore, .625 X 1.25 X 1.25 - .9776 cubic inches. As the area of a ¾ inch bar is about .44 square inch it follows that the length to be allowed for upsetting the head is, .9766/.44 = 2.22 - or about 2¼ inches.

Where large quantities of bolts are to be made the bars are heated in a furnace and headed by special machinery. Where the work is done by hand the tools are of the simplest character.