Tips for Isometric projection of machine blocks

Orthographic projection gives us views of objects from a particular direction only. Looking from the front, we get front elevation and from the top, we get a plan or the top view. The orthographic projection is complete in one direction only. To have an entire detail, we need to prepare at least three different views from three different directions. Still, for a quick reference, a pictorial view will be a better option. 

We have several ways of drawing pictorial drawings on a two-dimensional plane. It can be a perspective or oblique or isometric pictorial drawing. For Engineering Graphics, we usually use isometric projection to obtain the pictorial impression. In isometric projection, there are three principal axes inclined to each other at an angle of 120 degrees. The corresponding planes are the horizontal plane, the vertical plane, and the profile plane. 

For machine blocks, we usually practice with simple cubes, prisms, and pyramids with different orientations. The solid can be resting on the horizontal plane on the base or on one of the faces. Similarly, the axis of the solid can be perpendicular or inclined. For class 12, most of the time, the axes of solids are orthogonal to either the vertical plane or horizontal plane. 

The students begin construction by making of helping figure which can be either a square or rectangle or pentagon or hexagonal or a circle. Care should be taken on finding the center of the helping figure. Similarly, all the vertices must be indexed so that transfer of the points becomes hassle-free.

The next step will then be to prepare the isometric axes and required plane. Depending on the orientation, we transfer the points of the helping figure to one of the isometric planes. We can then draw the main axis of the required height. Please take the length of the axis at least one centimeter more on both ends of the axis. This helps in providing a quick grasp of the height or length of the solid to the viewer.

 After fixing the base and height of the solid, we can then proceed to complete the back end of the solid. For that, we can take either the transferred points on the front end as a reference or a point on the axis as the reference. For cubes, cuboids, and prisms, the base and top are symmetrical and the points on the top can be obtained by using projector lines from the corresponding points on the base. However, for a pyramid, we need to fix a point on the axis at the given height of the solid.

Finally, to give the finishing touch we will provide at least four dimensions. Three pertaining to length, width, and height, and one pertaining to the angles. Moreover, care should be taken of drawing proper extension lines, dimension lines, and dimensions. Please do not forget to print the name of the solid.