 Hello friends, myself SM Mutt, assistant professor, mechanical department of Walsh and Institute of Technology, Solapur. Today, I am going to explain regarding how to draw the ortho big projection, simple object of the ortho big projections. The learning outcomes for this session is to student will able to draw the simple ortho big projections are there. So, here I am showing one object, this object is to be there. Here, when you have to see the object in, you have to draw here front view in the direction of x. So, when you have to see that object from the front view, you have to calculate the maximum dimensions. Maximum dimension width is given as 75 and height is given as 60 mm, here it is given as 60. So, first of all I am making a block of 75 mm by 60 mm. So, whatever you have to draw in that boundary of this object, boundary of this box. So, there is what you call, there is no chance of any corrections. So, when you have to see the object in the front view, in the direction of x, this width is given as it is, this portion is seen as it is. So, I am first draw the object as it is dark one, this edge. Then the upper portions which is parallel to you and all these things, here it is the total height is 60 mm. So, from top the 10 mm and bottom 10 mm and centrally you get the semicircular part. So, first of all I am leave 1 mm and 1 mm from top to the bottom one, 1 mm and this 1 mm and the center line for this portion, it is given as now 20, 1 mm and 1 mm from top to the bottom one and the center line is. So, draw the center line for this portion because why the center line you have to draw it, whatever the dimensions you have to carry out, right or left, downward or upward all with respect to the center line. So, that is why in this portion also, it is a 75. I am also here draw the center line. So, with this center line you have to draw any dimensions, any age, any circular part. So, whatever the you have to draw it with respect to all these things. So, centrally one hole is to be there, what is the dimensions of the hole, it is a 525. So, take the you would say 525 centrally and draw it, 525 means radius is 12.5 because this hole it is parallel to you say an entity. Now, this semicircular part, what is the diameter for the semicircular part, whatever the center you have to draw it. So, take that dimensions that is it is a 5, radius is 25. So, take that dimensions is already you have to draw it here, then join the edges. These two semicircular parts are parallel to you where to draw as it is, circular part parallel to you as it is. Now, there is one guideway cut portion is to be there, depth and the depth is 10 mm from top to the bottom one and how much the width, width is given as 20 left and right. So, from the 20 and 20 mm from left and right, here you have to go for a 20 mm and from right word you are going for a 20 mm, and how much the depth, depth is given as up to here, there is a move downward 10 mm, downward 10 mm join it, it is whatever the parallel to you all the portions you have to show it. Now, there is one square hole is there this portion, square hole is there from left to right. So, what is the height for that, the height is 20 mm and 20 from the bottom one. So, from the bottom 20 mm, from this bottom 20 mm, it is given that 20 from this edge, this edge is given as 20 mm, so from here 20 mm you have to draw it and this portion is invisible. So, it is a hidden one, so how to show the hidden edges, think over that because this portion hole is there which from the front view it is not seen, it is invisible, but the hole is to be there and that hole you have to show in that front view, how to show you, think over that. So, so when that portions are invisible, they are not seen in the front view, at that time this portion you have to shown by a dotted line. So, invisible lines are there, invisible surfaces are to be there, they have to be shown by dotted lines and that hole is to be left to right and this portion now, this portion it comes in front of you, so join with the, so this is the front view. So, when you go for the front view, then you go for the top view, top view length is already from calculated, draw the generators, when you have to draw the generators, generators are faint one and what is the depth of this one, the depth is given as here it is 50 mm and this depth is 50, so these are the maximum dimensions block. Now, this cut portion is that is shown in the front view, now when it, when you have to see from the top view, this hatcher one, first one's rectangle is to be there sorry and the second one and this portion comes to on the same plane, so from the top view directly you have to draw it, carry forward the center line, then when you should see from the top view, this hole is invisible, so just now, just I am telling the hole is invisible, the edges you have to show by a dotted lines, this portion. Then this semi-circular part, this semi-circular part it is up to from the center line, so it is a 25, you go for a 2.5, draw one center line, this semi-circular part is up to, it is 10 mm from 10 mm, it is up to depth, it is to be this portion of this one, this edge is as shown as a dotted one, when it go for this one, this square hole, left to right and width is given as a 10 mm, so 5 mm and 5 mm from right to left, 10 mm, so just I am told that which portion is invisible, hidden one that is to be shown by a dotted lines, so this square hole is over, center hole is to be over, then this edge, when you to see from this semicircular part, that is to be up to certain depth, how much depth up to this 10 mm is to be there, so this portion you have to shown here by a dotted line up to here, up to that square hole, so this is all about the top view, so it is a front view in the direction of x, it is a top view, so it is a simple object of the front view and top view of the given object, that is the ortho drawing for the given object. References for this topic, that is the book, that engineering graphics by professor M. Ramade, volume 1, division publications, thank you.