This section is from the book "Practical Sheet And Plate Metal Work", by Evan A. Atkins. Also available from Amazon: Practical Sheet And Plate Metal Work.

Fig 211.

The setting out for the pattern is shown in Fig. 244. The bead is first of all allowed for by lengthening the pipes by the distance A B, which is equal to the length C D E measured around the bead. The position of the point G is found by the rule explained in connection with Fig. 239.

Fig. 242.

F is the middle point of B E. The points G and F are joined together and the length G J made equal to F B; then F H is drawn parallel to G J and made the same length as the arc K L. Now, if H be joined to J, the point W, where it intersects the line F G, will give the centre of gravity of the section shape. The line N M is now drawn in an average position, its length being marked off equal to the outline BK LO. M N is then produced to meet the centre line in T. The pattern is now laid out as that for a cone frustum, the lengths T M and T N being used as the radii, and the length of the arc R S P being made equal to four times the length of the quarter-circle on V M.

Fig 243.

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