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.

The method shown above will apply to all kinds of different-shaped circular vessels, the only difference being in the finding of the centre of gravity of the side section. Perhaps one further example in the way of a pan with its sides curved outwards will make the construction followed plainer.

In Fig. 240 a section showing the shape of the pan is given. The line A N is cut off equal to the length of the arc A D E and N P drawn square to it, and made equal to the radius O A. The line A F, as shown, is marked off equal to the chord A E, and F R drawn parallel to N P, the point R being determined by joining P to A. Then the point G, which is the centre of gravity of the arc A D E, is fixed by making O G equal to F R. The point L, which is the corresponding centre of gravity for the right-hand arc, is found by drawing G L parallel to A B and making K L equal to K G. G is next joined to A and the lines L M drawn parallel to G A. After S has been determined by making A S equal to A N, a semicircle is described upon S M, so fixing the point V on the line A N produced. The length of the line C V will give the radius for the disc.

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