Isometric Projection - 6

Isometric Projection - 6



Good Morning students and a warm welcome to each of you to today's class.

Let me start by congratulating you for taking online classes and making good progress in grasping intricate concepts over the last 5 sessions. Your response (i.e. submission of exercise question answers) is quite encouraging and hope you will continue to do so in times to come.   

Recall that in the last 5 sessions, you have leant the basics of Isometric Projection that included essentials of isometric projection, planar figures, frustums and single solids. I hope that you would have grasped the concepts well and feel confident in learning the next topic that is also the last in this unit. I encourage you to ask your doubts and queries by writing in the comments section at the end of the blog and I will make sincere effort at resolving them while you are working on your exercise. I will also expect quick response with answers from you.     

Today we will learn about Isometric Projection of combination of solids. 





Figure 1: Example of Isometric Projection of a combination of Solid


There will be one such question asked in the final Board examination whch carries 12 to 14 marks out of 70, therefore, pay close attention to the concepts explained herein. You can spend as much as 30 minutes in answering this single question. The sooner you can do it the better.


1. What is a combination of solids?   

You have studied solids like cones, cylinders, prisms and pyramids. You have learnt to draw the their orthographic as well as isometric projections. A combination of objects implies that any two of these objects are placed atop each other. When two such objects are placed together with their axes co inciding with one another, the objects are called as being centrally placed. For example, a triangular pyramid placed centrally over a cylindrical slab.


2. How can you draw centrally placed objects? 

Drawing of centrally placed objects is an elaborate as well as intricate piece of Isometric Drawing. You will agree that it becomes a simple exercise if you follow a step by step approach as enunciated below.

Step by step approach    

I have demostrated this approach practically in the class, therefore there is no need to mug up the text.
  
1. Draw the helping figures (except for a circle and a sqare). You may need to draw multiple figures. Locate the centres of these figures.

2. Draw the isometric projection of the object that placed below to other in the usual manner as you draw single solid object. With the only exception that it is drawing very light.

Note: If you draw the first object in bight, then you might not make out the second object and might get confused. Therefore, draw this object in light shade using less pressure on the pencil. 
 
3. Find the centre of the top face of this first object that you drew in step 1 with help from the helping figure.

4. Extend the correct height from the centre and draw a 30-30 cross at the top.

5. Construct the face of the second object around the centre so located. 


We will now draw some projections as mentioned in the exercise that given below:



Exercise - 6: Combination of solids  

Instructions

a. Write Title, sub title, indicate the direction of viewing, show the common axis and mention dimensions in all the questions.
b. Solve these questions in your drawing file (which will be checked and verified physically once you are asked to submit when school reopens)
c. Please take a picture of your answers and post it in the EG WhatsApp Group.

Q 1. Draw the isometric projection of a square pyramid of base side 30 mm and height 50 mm placed centrally on top of a cylindrical slab of diameter 60 mm and thickness 30 mm.

Q 2. Draw the isometric projection of an equilateral triangular pyramid of base side 30 mm and height 50 mm placed centrally on top of a hexagonal slab of base side 40 mm and thickness 30 mm.