Fig. 2811.
Let it be required to make a pattern for a section of pipe such as shown in section and in plan in [Fig. 2810], which is from “The Pattern Maker’s Assistant.” This pattern would be made to mould, as shown in the section, lying horizontally, and must therefore be made in two halves, the line of joint for the two halves being along a b in [Fig. 2811].
“The body a and the branch b would be made separate from the flanges, and would be reduced in diameter at the ends to receive them. To form a, take two pieces of timber, say three inches longer than the length of a, including the core prints, and measuring a little more than half the diameter of the pipe one way, and a little larger than the full diameter of the pipe the other way, and glue them together at the ends for a distance of 11⁄2 inches, which will serve to hold them while turning them in the lathe.
“The pieces may then be turned in the lathe to the required diameter. During this turning, however, it is essential to insure that the joint of the two pieces be exactly in the centre, otherwise one half of the pattern will be (when the halves are separated) thicker than the other.
“The ends are then turned down to receive the flanges, the reduced diameter being necessary so as to leave a shoulder for the flanges to abut against to keep them true, or at a right angle to the axial line of the body. The branch is turned up in the same way, and the flanges are then turned and put on.
“The end of the branch may be cut to fit the circumference of the body as follows:—
Fig. 2812.