Ellsworth M. Longfield

“ Suppose a piece of round rod is formed in the rolls to a true circular profile. A solid of revolution would be created because a ring slipped over the rod and caused to move around it to the right or to the left would always be the same distance from the center of the profile to which the rod was formed. A piece of bar iron formed to a circular profile would also be a solid of revolution. This solid could be regarded as being generated by a rectangle revolving about a center point. Figure 132 is drawn around two arcs whose center is the center of the elbow. ”

“ The spacing of the profile is transferred to each line of stretchout and is numbered to correspond. Measuring lines are drawn through each point in the lines of stretchout. Starting at point 1 of the profile an extension line should be traced upwards to the miter lines, and from there an extension line to lines 1 of the stretchouts should be drawn. Notice that two stretchouts are served by each intersection of the miter line. Extension lines from the elevation into any stretchout must always be drawn at right angles to the sides of the pipe. ”

“ The measurements for the several pieces are taken from the elevation and are plainly marked. The pattern for the body piece, Fig. 140, is obtained by adding 3-inch double edges to the front elevation, and notching for a 13⁄8-inch cleat as shown. The stretchout for the end piece is determined from the front elevation, and the width from the profile. Single edges 1⁄4 in. wide are added to each side. ”