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.
The header consists of a disc in which a hole has been drilled to correspond to the diameter of the bolt. A handle 12 or 15 inches in length is welded to the disc. Such a tool is shown in Fig. 49. The hole should he about 1/32 inch larger than the nominal size of iron. To make a bolt with this tool: First cut off the iron to the required length; then heat the end to be headed, to a dull straw color; strike the end with a hammer or against the anvil and upset it so that the portion intended for the formation of the bead will not pan through the header. Then place the hole of the header over the equate hole in the tail of the anvil and drop the cold end of the bolt through it. Strike the projecting portion of the bar and upset it until the requisite thickness of bead is obtained. This will probably leave a head of curved but irregular outline. Remove from the header and square the head thus Upset on the face of the anvil. This will probably thicken the head. Again drop the cold end through the header and strike the head until it is reduced to the. proper thickness. After which, again square the edgea on the face of the anvil. In doing this work, the smith will hold the header in his left hand. The work will be facilitated if a helper assists with a sledge hammer.'
There are a number of simple tools in use for clamping the bar while it is being headed so as to avoid the preliminary upsetting.
We have now studied the methods to be followed in the execution of two simple jobs. One involved drawing out and the other upsetting. Sometimes both processes must be followed in one job. Whan there is a choice between the two the smith should take the one involving the least amount of work.