To set out the pattern for a gutter or moulding angle which is required to fit on or into a greater angle than a right angle, will demand a somewhat different method to that shown in the last case. Thus, suppose an elbow is wanted to fit on to an angle of 130°, as in Fig. 178, then some such method as that illustrated by
Fig. 179 will have to be used. The shape of the section is first set out and a line E F drawn across the top.
Two parallel lines C D and A B are drawn perpendicular to E F, these representing the width of gutter. Across these a line E A is drawn, called the joint line in the figure, making an angle of 130 / 2 = 65° with A B. The gutter section is divided up into any number of parts, such as 0 to 1, 1 to 2, 2 to 3, etc., and lengths equal to these set out to obtain the full girth of the gutter. It will be seen that the gutter section is divided into fourteen parts, hence the total girth of the section as laid out on the girth line of pattern will run from 0 to 14, as shown by the numbers. Through each division point on the section lines are drawn square to E F, and produced until they cut the joint line. From the points where these lines meet the joint line, dotted lines are drawn down on to the pattern, and through each division point on the girth line square lines drawn to meet them. Thus, consider point 8 on the gutter section, follow the line down to joint line, and then along dotted line to pattern, where it will intersect with the line drawn through point 8 on the girth line. This gives a point on the curve to form the cut of pattern. In the same way all the other points can be determined, and thus the pattern completed. No lap will in this case be needed, the edges of metal being butted together and soldered.
In bending sheets or plates for angles of moulding, care must be taken to bend them into pairs of right and left hand.
Where the gutter or moulding has many bends, it must be formed to the exact shape of section, or else it will be most difficult to fit the corner joint together.