Fig. 2902.
To bend an angle iron into a circle, with the flange at the extreme diameter, the block and pins shown in [Fig. 2902] are employed. The block is provided with the numerous holes shown for the reception of the pins. The pins marked 1 and 2 are first inserted and the iron bent by placing it between them and placed under strain in the necessary direction. Pins 3 and 4 are then added and the iron again bent, and so on; but when the holes do not fall in the right position, the length of the pin-heads vary in length to suit various curves.
To straighten the iron it is flattened on the surface a and swaged on the edge of the flange b, the bending and straightening being performed alternately.
Fig. 2903.
When the flange of the angle iron is to be inside the circle, as in [Fig. 2903], a special iron made thicker on the flange a is employed. The bending is accomplished, partly by the pins as before, and partly by forging thinner, and thus stretching the flange a while reducing it to its proper thickness.
To Forge a Bolt by Hand.—The blanks for bolts must be cut off sufficiently long to admit of one end being upset to form the head, the amount of this allowance, obviously, being determined by the size of the head.