Problem 21
VEGETABLE PARER
41. The Vegetable Parer.—Figure 124 shows an elevation of a vegetable parer which is in the form of a right cone cut by a curved plane.
The Elevation.—A "vertical" line which is to be used for the center line, or altitude of the cone, is drawn first. At right angles to the lower end of this line, the base of the cone is drawn. This base is to be ¾ in. long and is to have ⅜ in. on each side of the center line of the cone. A distance of 17 in., which will locate the apex of the cone, is set off upon the center line. The apex and the ends of the base line are connected by the slant height lines. At an altitude of 4 in. a curve that cuts the cone, as shown in Fig. 124, is drawn in. This curve may be drawn to suit the ideas of the designer, and is in reality the miter line.
The Profile.—A whole profile, using extension lines to locate the view, is drawn. The profile is divided into twelve equal parts and each division numbered. Extension lines are carried from each division of the profile upwards to the base of the cone, and thence to the apex. Each one of these extension lines intersects the miter line at some point. Horizontal lines from each of the intersections of the miter line, Fig. 124, are drawn over to the slant height.
The Pattern.—The arc of the stretchout, Fig. 125, using the apex as a center and a radius equal to the slant height of elevation, is next drawn. The spacing of the profile is transferred to the arc of stretchout and the divisions numbered to correspond. From each of these points a measuring line of the stretchout is drawn to the apex. Starting at point 1 of the profile, the extension line should be followed up to the miter line, then horizontally to the slant height? With a radius equal to the distance from this point to the apex, and the apex as a center, a curved extension line should be drawn over into the stretchout until it intersects both lines that bear the number 1. (Is this procedure similar to that of parallel line drawing? Wherein does it differ?) In like manner, each intersection on the stretchout may be traced out. A curved line passing through these points will give the miter cut. A ¼-inch lap is added to one side of the pat-
