Question 2
(2) (a) . Shows the front elevation of a right cone cut by two planes PQ and RS.
Draw half size, in first angle projection;
- The given elevation;
- A complete plan
- The surface development making PR the seam.
Observation
Question 1A
This is a question on a cone truncated at both ends (the top and bottom). The candidates
where to draw the plan and develop the truncated cone using the shorter side as the seam.
Many candidates attempted this question but only a few got it right.
Candidates were expected to do the following:
- THE GIVEN ELEVATION
- For drawing the given elevation half full size......../li>
- For drawing the cutting planes PQ and RS at 30 15 to the horizontal respectively......
- COMPLETE PLAN
- Project down from the elevation to draw the plan.
- Draw base circle on plan and divide it into 12 equal parts.
- Project up from the divisional point on the circle to the base of the cone at front elevation.
- Project lines from the base to the apex of the cone.
- Project down from the cutting plan PQ to locate the points from the inner curve on the plan.
- Join the points to draw the inner curve.
- Project from the cutting plane RS to locate the points the outer curve on the plan.
- Join the points to draw the outer curve.
- Hatch the cut surface on the plan.
- SURFACE DEVELOPMENT
- Draw the horizontal lines from the cut surfaces to the end of the cone for true lengths.
- Draw the perimeter and dividing it into twelve equal parts.
- Join the division points to the apex.
- Draw the arcs for development from the lengths.
- Locate the points of the cut surfaces and joining the points to obtain the curves of the upper and lower cutting surfaces.
- Use the side PR as the seam.
- Draw wealthy
The solution is shown below:
