 Welcome back MechanicalEI! Did you know that even the simplest machines are made using machine elements? This makes us wonder, what are machine elements? Before we jump in, check out the previous part of this series to learn about what solid geometry is. Now, machine elements refer to an elementary component of a machine. These elements consist of three basic types. First, structural components such as frame, bearings, etc. Second, mechanisms that control movement in various ways, such as gear trains, belt or chain drives. And third, control components such as buttons and switches. Orthographic projection is a means of representing three-dimensional objects in two dimensions. There are many times when the interior details of an object cannot be seen from the outside. We can get around this by pretending to cut the object on a plane and by showing the sectional view. The sectional view is applicable to objects where interior details are intricate and would be very difficult to understand through the use of hidden lines. The true projection of a threaded portion of a part consists of a series of helixes. And it takes considerable time to draw them. Hence, it is the usual practice to follow some conventional methods to represent screw threads. In this method, the crests of threads are indicated by a continuous thick line and the roots by a continuous thin line. For hidden screw threads, the crests and roots are indicated by dotted lines. For threaded parts in section, hatching should be extended to the line defining the crest of the thread. In the view, from side, the threaded roots are represented by a portion of a circle drawn with a continuous line of length approximately three-quarters of the circumference. Hence, we first saw what machine elements are and then went on to see how threaded parts are represented in sectional views. With your feedback to help us make better videos, thanks for watching. Also, thanks a lot for those constructive comments. You helped the channel grow. So, here are the top mechanical EIs of our last videos. In the next episode of Mechanical EI, find out what thread designation is.