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. 381, let A B D C represent the elevation of an article of which Gr H I J is the half plan at the base and K L M N O P the half plan at the top. A C of the elevation is the normal profile or profile of one of the square sides, and L H and M H of the plan show the miter lines between the square sides and the gore piece. C E and D F, the elevations of the miter lines H M and I N, are shown as part of the design, but are not necessary in cutting the pattern.

As only the normal profile, which would be used in cutting the pattern of one of the square sides, is shown in the elevation, the first step will be to obtain from this a profile of the gore piece, or in other words, a section upon its center line, R H of the plan. Divide the profile A C into any convenient number of parts, and from the points obtained drop lines at right angles to A B, cutting the miter line L H in plan, as shown. From the intersections obtained on the miter line L H draw lines parallel to L M, as shown, cutting the other miter line H M, and continue them indefinitely. At any convenient position outside the plan draw the line A1 A2 parallel to H R, and draw a duplicate of the profile A C in the same relative position to A1 A2 that A C holds to A B, and divide the same into the same spaces as A C, all as shown by A1 C1 From the points in A1 C1 draw lines parallel to A1 A2, cutting lines of corresponding number drawn through the plan of the gore piece. A line traced through these intersections, as shown from A2 to C2, will be the profile of the transition piece from which to obtain the stretchout for the pattern.

To obtain the pattern proceed as follows: Upon R1 R2, a continuation of H R, place the stretchout of the profile A2 C2, as shown by the small figures, through which draw the measuring lines, as shown. These are now to be intersected by lines drawn from points of corresponding number upon the miter lines H L and H M. Lines traced through the points of intersection, shown by R T and R S, will give the desired pattern.

Fig, .381. - The Pattern for a Gore Piece in a Molded Article, Forming a Transition from a Square to an Octagon.

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