Problem 3. Draw the Top view and front view of a circular lamina if the surface of the lamina is perpendicular to HP and inclined at 30° to VP.

Solution: The projections of the circular lamina is shown in figure 3. Let us first assume that the plane is perpendicular to HP and parallel to VP.  The Front view will be a circle and with diameter equal to the diameter of the lamina. Divide the circle in to 12 equal parts and label then as 1’, 2’, 3’, …., 12’. The top view will be a straight line 1-7 , parallel to XY line and can be obtained by drawing projectors from 1’, 2’, …. and 12’. Since the circle is inclined at 30° to VP and perpendicular to HP, reconstruct the top view such that the straight line is inclined at 30° to XY line.  Let the respective points be 11, 21, 31, …. 121.    Draw vertical projectors from points 11, 21, 31, …. 121  to meet  the horizontal projectors from points 1’, 2’, 3’, … 12’ to obtain the points 11’, 21’, 31’, …. 121’ in the Front view. Draw a smooth curve  passing through  points 11’, 21’, 31’, …. 121’  to obtain the Front view of the circular lamina.

 

 

Figure 3. Projections of the circular lamina mentioned in problem 3.