|
|
|
Hand Forging by Thomas F. Googerty
|
78 HAND-FORGING
In twisting there are two methods. Flat bars that are not too heavy may be twisted while cold, providing the stock is of the same thickness throughout its length. If it be swelled or tapered it must be twisted while hot. The operation of twisting while the iron is hot is very simple. Say, for example, a bar 10 in. long and 1/2 in. square is to be twisted its entire length. The piece should be cut about 11 in. long. The extra inch is left on until the piece is twisted in order that there may be extra stock to catch in the vise, and when twisted it is cut off. The piece is heated as much at one time as possible in a forge. The heat must be uniform and about yellow; it must not be a welding heat, as this destroys the texture of the iron. When the bar is heated it is caught by one end in a vise, and with a monkey wrench on the other end it is twisted to the right. (See Fig. 44.) If any part of the bar is twisting faster than another, or too much, a little stream of water is poured on the part twisting too fast. In case one part is twisted more than is desired it may be remedied by reheating it and cooling each side with water, then twisting back as desired. A little practice will enable one to get them uniform.
In Fig. 45 may be seen some illustrations of twisted bars. At A three bars of 1/4-in. round iron are welded at the ends, and are then heated
|
|
|
Hand Forging by Thomas F. Googerty