Page:Sheet Metal Drafting.djvu/60

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46
SHEET METAL DRAFTING

Problem 9
THE SCOOP

25. The Scoop.—Figure 66 shows an ordinary flour or sugar scoop. Briefly described, any scoop is a cylinder cut off at an angle. A head is soldered in, and a handle is attached to the head. Figure 72 shows another type of scoop, the body being cut by a curved plane and a cylindrical handle being attached to the head.

The elevation should be drawn, using the dimensions given in Fig. 66. It is not necessary to show the handle in the elevation. After the profile. Fig. 67, has been drawn, it should be divided into twelve equal spaces. Extension lines from each division of the profile should be carried through the elevation, Fig. 68, until they meet the miter line.

Definition of a Miter Line.—The miter line is the line of junction between two shapes; these shapes may be alike or unlike. The miter line of the scoop is the line of junction between the body of the scoop and an imaginary cutting plane.

The line of stretchout is drawn at right angles to the elevation. The spacing of the profile must then be transferred to the line of stretchout and numbered to correspond. The measuring lines are now drawn in. The extension lines from the profile meet the miter line at seven points as shown. From each of the seven points of intersection on the miter line a dotted extension line is carried over into the stretchout. These extension lines must be drawn parallel to the line of stretchout. Starting from point 1 of the profile, follow the extension line until it meets the miter line, and from there follow the dotted line until it meets lines 1 and 1 of the stretchout. Small circles are placed where the dotted line crosses the measuring lines No. 1 of the stretchout in order to mark them definitely. In like manner every point of the profile can be located in its proper position in the stretchout. A curved line drawn through these points will give the miter cut of the pattern. A standard tin lock is added to each side as shown. Over-all dimensions should be placed on the pattern as shown. The pattern for the head can be obtained by reproducing the profile and adding a ⅛-inch burr. It is not necessary to allow for the dish of the head because it is so slight.

Up to this point the discussion applies to both types of scoop,