In making this drawing it is necessary to make half end views as suggested at a and b in order to assume elements to use in obtaining the line of intersection and which will also aid in laying out the surface pattern. The points assumed in a are projected across the surface of the smaller cylinder to the surface of the larger cylinder, from which they are projected into the front view where they are intersected by projection lines from the points assumed in b. The line of intersection is traced through the points where the horizontal and vertical projection lines from corresponding points meet. The rectangle forming the surface pattern of the large cylinder should then be laid out and the positions of the vertical elements of the cylinder obtained from the top view, (Figure 1). The outline of the line of intersection may then be determined by projection or measurement from the front view, (Figure 2). The size of the rectangle (Figure 4) containing the surface layout of the smaller cylinder is determined by the length of its circumference and the length of the longest element in this cylinder. The lines representing the elements should then be drawn in their proper positions and the length of each measured in either the top or front views and transferred to its corresponding line in the rectangle. The curved outline caused by the intersection of this cylinder and the larger cylinder may then be traced through the points thus obtained.

Drawing Problems.

57. Make three views and develop the surfaces of two cylinders (Figure 86), one of which is 21" diameter and 31" high, intersected at an angle of 45° by a smaller cylinder, 13" diameter. The distance from the top of the larger cylinder to the intersection of the center lines is ". From this point to the base of the smaller cylinder is 31". The front view of these cylinders is indicated at 2, Figure 86. The proportions of this problem are such that the position of the surface patterns should be represented by rectangles having their longest sides parallel with the end margins of the drawing paper. This will cause all points in these developments to be obtained by measurement rather than by projection.

3

2

4

FIGURE 86.

58. Draw a front view only as represented in 4, of the funnel suggested in 3, of Figure 86, and then lay out the surface patterns for the funnel. The proportions are:

59. A rectangular prism having an end 11"x2", intersects a cylinder which is 21′′ diameter, 33′′ high, as indicated in Figure 87, making an included angle of 60° between the prism and cylinder. The distances a and b are 3" and 11". Make front and top views and develop surfaces of both cylinder and prism.

60. An equilateral triangular prism having a base with sides 13" long, intersects a cylinder which is 2" diameter, 31" high, as indicated in Figure 88, making an included angle between prism and cylinder of 60°. The distances a and b are " and 11". Make number of views necessary to assist in laying out surface patterns.

61. Make necessary views and lay out surface patterns for the three-part elbow suggested in a and b of Figure 89.

62. Make all necessary views and layout surface patterns for the four-part elbow suggested in c of Figure 89.

DRAWING PROBLEMS FOR THE WOODWORKING SHOPS

Constructive Design is the adaptation of the fundamental principles of design to the proportions, fitness of form, size and weight of materials used in the construction, of the special problem under consideration.

A constructive design for some particular object made by more or less original effort on the part of the pupil is a matter of great importance, and work of this character may have its beginning through the medium of a few simple problems especially selected for the purpose. In his first attempts to design, the average pupil is apt to aim far beyond his capacity, especially in regard to his constructive ability and the time at his disposal in which to work out and execute the problem that he has undertaken.

The secret of success in beginning constructive design lies in the selecting for the first problem an object that may call for a design which shall be of almost severe and extreme simplicity and then making the working drawing with the greatest care, attention to constructive detail and nicety of execution. Unless this is done, there is danger that many things that are impossible will creep into the design and thus make it of no practical value. Then there is the question of utility. If a problem is worth the time and attention of both shop and drawing room, the resulting product ought to be of value in itself. It should have some specific use and not be merely a thing to look at. With this thought in mind the following problems have been selected. The pupil should be guided by the suggested outlines and sizes presented and make a pencil drawing which is then to be traced and blueprints made for use in the shop. The accompanying halftone illustrations are made from photographs of work executed by pupils in their first year in the high school.