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.

Instead of turning the moulding round the corner and up the gable by two joints, as in the last case, sections of cornices may be made that will come together in one joint at the corner. This particular method of jointing is illustrated by Fig. 187. The shape of one of the mouldings must first be fixed (in this case the one along the eaves), and the section for the other projected from it.

Fig. 187.

In Fig. 188 a section of the horizontal moulding is shown set out, and from this the shape of the gable cornice projected. The latter is obtained by drawing a line S S, at any part, square to the gable-slope line, through the numbered points on the eaves section, running up lines perpendicular to it, and cutting these off, to the left of S S, equal in length to the similar lines on the eaves section. Thus, a' 1' = 0 1, a" 2' = a 2, a0 3' = a 3, and so for the other pairs of corresponding lines. The points obtained are then joined up (as shown by the dotted lines), the resulting figure being the shape to which the moulding for the gable must be made.

In marking the pattern it should be remembered that the cut for the eaves moulding will come out as in the last case - that is, the same as in an ordinary flat square-mitred joint. The cut for the pattern of the sloping cornice will be obtained by first setting down a girth line equal in length to the girth of the projected section - that is, by making 0" 1" = 0' 1', 1" 2" = 1' 2', 2" 3" = 2' 3', and so on. The lengths of the construction lines on the pattern are measured from the elevation - that is, 0" 0° is made the same length as 0' 0, and 1" 1° = a' 1, 2" 2° = a" 2, 3" 3° = a° 3, 4" 4° = b' 4, and in the same way for the remaining lines.

For the joint to be made properly and with ease, care must be taken that the setting out is done accurately, and that the sheet metal is bent to the exact shape of the respective sections.

Fig. 188.

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