Procedures for Development Methods

PROCEDURES FOR DEVELOPMENT METHODS

1. Parallel line method

Suitability: This method is suitable for the solids having uniform cross section for their full length (Example: Prism and Cylinder)

Procedure:

1. Draw the topview and frontview of the solid.

2. Determine the development length (L) which is equal to the perimeter of base and mark adjacent to the front view.

3. Refering the front view (for height) and using the development length marked in previous step, complete the outer lines of the layout.

4. Locate the distance between the lateral corner edges by measuring them from the true size views. (ie., from the top view) and mark the same on the stretch out line and name the corners. 

5. Draw the folding lines perpendicular to the stretch out line (ie., length of development line) using thin lines.

6. For cylinders, the stretch out line of the curved surface is taken as the circumference of the base circle which is divided equally into any number of equal parts (normally 12)

7. If the object is cut by a plane, mark the same in front view and project it to the development. 

2. Radial Line Method:

Suitability: This method is suitable for the solids having uniformly varying cross section for their full length (Example: Pyramid and Cone)

Procedure:

1. Draw the topview and front view of the solid.

2. Draw one of the slant edges as a vertical line and draw the true size of the slant surface (triangle) from that line, joining at the vertex.

3. Draw the outerlines using thicklines and the folding lines using thin lines.

4. For cones, divide the circumference of base into any number of equal parts (normally 12) and draw the sector of the development by determining the angle subtended at centre using the true length of the generator.

5. If the object is cut by a plane, mark the same in front view, taking the points of intersection on cutting line as P, Q, R etc., and project the cutting line to the development.

3. Triangulation Method

Suitability: This method is suitable for the solids which can be assumed to consist of number of triangles.

Procedure: 

1. Draw the topview and front view of the solid.

2. Divide the topview and front view into triangles. 

3. Draw the true length diagram to find the true lengths of the sides of the triangle.

4. Locate the surface opening line and draw the triangles in an order side by side using the true length taken from the true length diagram. 

5. Complete the outerlines using thicklines and draw the folding lines using thin lines.

4. Approximate method 

Suitability: This method is suitable for the solids bounded by double curved surfaces. 

Example: Sphere

(Note: Triangulation method and Approximate method are not dealt in this text books)