BENDING WITH BALLS OR BOBBINS.
This style of work is much practiced on small pipes, such as 2 in. to 3 in., especially by London plumbers. Method: Suppose your pipe to be 2 in., then you require your ball or bobbin about 1/16 in. less than the pipe, so that it will run through the pipe freely. Now pull the pipe round until it just begins to flatten, as at Fig. 37, put the ball into the pipe, and with some short pieces of wood (say, 2 in. long by 1½ in. diameter) force the ball through the dented part of the pipe, or you may use several different-sized balls, as at A B C, Fig. 40, and ram them through the pipe with a short mandrel, as at D M. You will require to proceed very carefully about this ramming, or otherwise you will most likely drive the bobbins through the back at L K J. You must also watch the throat part, G H I, to keep it from kinking or buckling-up; dress this part from the throat toward the back, in order to get rid of the surplus in the throat.
FIG. 40.