In Fig. 469, let A B D C be the side elevation of the required article. Below it and in line with it draw a plan, as shown by E c d F H G. From D in the elevation erect the perpendicular D L. Then L C represents the flare of the article and C D is the width of the pattern throughout. Across the plan, at the point where the curved end joins the straight sides. draw the line d H at right angles to the sides of the article. As the plan may be drawn at any distance from the elevation, this line must be prolonged, if necessary, to meet C D extended. Produce C D until it meets d H, as shown by g. Then g D and g C are radii of the curved parts of the pattern.
Lay off on a straight line M O in Fig. 470, the length of the straight part of the article, as shown in the plan by c d. At right angles to M O draw M S and O B indefinitely. Upon these lines set off from M and O the distance g C, locating the points S and R, the centers for the curved portions of the pattern. From S with the radius g C strike the arc M U indefinitely. In like manner, with same radius, from R as center describe the arc O V. From the same centers, with radius equal to g D, describe the arcs N T and P W. Step off the length of the curved part of the article upon either the inner or outer line of the plan, and make the corresponding are of the pattern equal to it, as shown by the spaces in N T and P W. Through the points T and W draw lines from the centers S and R, producing them until they cut the outer area at 0 and V. At right angles to the line S T U or R W V, as the case may be, set off V X Y W, equal to MOPN, which will be the other straight side of the pattern. Then U M O V X Y W P N T will be the complete pattern in one piece.
If it were desired to locate the seam midway in one of the straight sections, in adding the last member as above described, one-half would be placed at each end, instead of all at one end, as shown. In like manner such changes may be made as are necessary for locating the seam at any other point, or for cutting the pattern in as many pieces as desired.
Fig. 480. - Plan and Elevation.
Fig. 470. - Pattern.
The Pattern of a Regular Flaring Article Which is Oblong with Semicircular Ends.