This section is from the book "The New Metal Worker Pattern Book", by George Watson Kittredge. Also available from Amazon: The new metal worker pattern book.

In Fig. 325 is shown an elevation of a bifurcated pipe, all arms being of the same diameter. In this problem, as in many others, it becomes necessary to first make a correct drawing of the intersection of the parts showing the miter lines correctly; after which the method of laying out of the miter patterns is the same as that employed in several other problems immediately preceding this. If, in this case, each arm of the pipe be divided longitudinally into two equal parts, as shown by the center lines, and each half be considered as a separate molding the correct position of the miter lines will at once be determined. Thus the intersection of the three bisecting lines at R gives the point at which the miter lines starting from the points P, E and K must meet.

Fig. 325. - The Pattern for a Bifurcated Pipe.

In line with the upper end of the pipe draw a profile of it, as shown by A C B. A profile will also be needed in one of the oblique arms, a half only being shown at A' C B' on account of the limited space. For the pattern of the upper portion of the pipe, divide the profile A C B into any number of equal spaces, and place the stretchout of the same on any line drawn at right angles to S P, as shown by the continuation of S D to the left, and draw the usual measuring lines. Next drop the points from the profile A C B parallel with S P till they cut the miter line PRE; then placing the T-square at right angles to S P, drop the points from the miter line P E into measuring lines of corresponding number. A line traced through these points of intersection, as shown from E" to P', will give the miter cut on the lower end of the pipe SDEP, one-half of which only is shown in the engraving. The pattern for the piece E F J K is obtained in exactly the same manner, and might be obtained, so far as the half indicated by C' B' on profile is concerned, from the original profile, by simply continuing the lines through to the miter line J F, as shown. For simplicity, therefore, the profile A' C' B' is divided into the same number of equal parts as the original profile, and a stretchout of it is placed upon any line, as T U, drawn at right angles to E F. The points are then dropped from the profile both ways, cutting the miter lines KRE and J F, after which, with the T-square placed parallel to T U, they can be dropped into the measuring lines of the stretchout. Lines traced through the points of intersection will constitute the required pattern, as shown by K' R' E' R" K" X W V.

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