 Think and analyze TA 101 lecture number 4. So, let us take a look at one of the examples in orthographic views, but before that some fun. Are you available on Fridays or Saturdays for your AutoCAD workshop? If you are wonderful, so we will arrange for the workshops on more than 2 days or rather both days. So, you are 12 batches we will divide those batches into 6 and 6. So, 6 can go on Fridays and 6 can go on Saturdays and then the next week we will have the AutoCAD lab you know Fridays. Monday we have bunch of lectures, Tuesday bunch of lectures, Wednesday, Thursday bunch of lectures, come Friday and you are fried right Friday. Anyways do not worry about that does not matter sense and nonsense some more fun. Did you have a lunch yet it is 2 o clock? So, the reason why I have posed this picture up is to make a point we tend to spoon feed you. Your academic appetite gets satiated over time, gets satisfied over time and that is the reason why that is one of the reasons why you tend to lose interest in academics. In some time may be 1 semester, 2 semester, 2 4 semesters which is bad news bad northeast or south not good. The point that I am making is you should never stop asking questions no matter what can make so otherwise. Keep your curiosity alive and feed me with it I am hungry for your curiosity do not take me for granted question me challenge me. I am bound to make a lot of mistakes I keep making a lot of mistakes you know so always question me challenge me I will be very happy to answer questions then and there if not then definitely in the next lecture. So, this is pertain to the question that I had posed in the previous lecture. So, given the three orthographic views is it possible for us to uniquely represent a solid or vice versa can a solid can any solid be uniquely represented by three orthographic views. So, this is a counter example. So, let us say you have a block or a cube you have a smaller cube on the back side on the back face you have again a smaller cube on the front face cube on the side cube on that side cube on top cube on bottom and then you have a void in there. So, this is pretty much like you know you have this cube placed dot at the center of the space and all such cubes placed on the respective centers of the respective faces. Now, for this solid is it possible for you to represent this uniquely using orthographic views let us see hinge line separating the front view from the top view and another vertical hinge line separating the front view from the right side view. Now, if you sketch the views out you will probably be getting something like this front view top view and the right hand side view exactly the same story exactly the same result. Now, watch out for the conventions that I use I use dash dot dot dash dot dot to represent the hinge lines. So, this object is symmetric both along the vertical as well as along the horizontal. So, I am using dash dot dash dot this convention to represent the line of symmetry usually it is also used to represent the center line. So, since these two are also symmetric about the horizontal and the vertical I am going to be using those lines and of course, where are my projection lines they have to be there. So, the final lines are thick solid lines whereas, the construction lines are gray lines just for reference it is always a nice idea to have projection lines because otherwise things become very difficult to comprehend orthographic views uniquely represent solid almost always, but not every time. For instance in this case it is not possible for you to represent the internal void here. So, be careful about that, but almost always these views they work. Orthographic projections is the fourth lecture second week let us take an example. So, we have to draw the orthographic views of the solid dimensions of which are given let us work it out one by one. So, this could be a little boring, but if you follow the construction you know step by step things might be enlightening for you. The first step preparing your sheet write your name write your subject what you are working on give all the details in the box over here and this is the convention we use for the third angle orthographic view. So, if you have a cone the cone from this side is going to look like two concentric circles and of course, this would look like a trapezium mention the sign over here or depict the sign over there and actually although this is at the center or on this at the center of the sheet it actually is on the bottom right corner of your sheet right there. So, once you have prepared your sheet you are ready once again mention the subject more importantly mention the scale. So, using the scale one is two two now we are looking at the object along this direction. So, this would be the front view of the object that would be the top view and the right hand side view would be from that side draw the hinge line, but before that just estimate based on the dimensions as to how your bounding boxes for the front view the top view and the right hand side view are going to be placed. Once you make those preliminary measurements start with the hinge lines first. So, this is the hinge line that separates the front view from the top view make the bounding box. Now, this is about 114 millimeters this is about 32 here and this is about 32 over there 114 plus 32 plus 32 114 plus 64 which would be something some number 178 I believe that would be the length of this bounding box and the height would be about this dimension 45 plus 18. So, since I am using the scale 1 is to 2 178 over 2 would be 89 I am going to mention there and that is going to be 31.5 45 plus 18 divided by 2. So, the scale 1 is to 2 would mean that 1 would actually represent 2 scale and this would represent that I am actually you know scaling this object down by half 1 is to 2. So, this is the front view. So, I am going to mention that over here top view mention that over there about the hinge line draw the projection lines the length remains the same. This dimension over here would be about 32 64 divided by 2 and I will finish this bounding box and I will draw the vertical hinge line here I would be sketching my rather drawing not sketching drawing my right hand side view extend the projection lines and I will draw the bounding box over here. So, this length is the same as this length 32 is about 31.5 is pretty much like a square is a profile view. So, the side view is also called the profile view. So, my profile view for instance I should have also extended the lines from here from here and I would have drawn the 45 degree line over here I should have drawn that be very careful I am bound to make a lot of mistakes. So, let us start with the final version of the drawing I will see this edge from here to here I will see this vertical edge I will see the vertical edge over here although this is like a semi circle I will see the corner of that or the extreme of that I will see this horizontal edge from both sides and then I am going to draw a projector from this point over here up to the top and on this projector would lie this edge likewise on this vertical projector would lie this edge well I am actually going to be working on the right hand side view alongside. So, this is the edge that I draw here the second edge that I draw here then I would draw this edge. So, this is about 64 38. So, 64 minus 38 is whatever dimension divided by 2. So, this dimension is given 13 13 divided by 2 from both sides I would draw this projector from here to here likewise the other vertical projector this dimension is 18. So, I will mark it 9 note that I am working with once 2 scale that dimension is 13 over 2 6.5 this one is again 6.5 this is 13 from bottom from here this is about 6.5 from there I will draw this vertical edge down and this vertical edge down I will also see this edge right there am I done not quite would I be seeing this edge yeah because this would actually correspond to this edge right there am I done again not quite how about these circular holes or cylindrical holes I will have to depict that as well. Now, if I look at this object from this side are these holes visible no, but they have to be shown somehow. So, I am going to show that using hidden lines or dashed lines never the less I will work on them a little later. Let me project this guy here on to the right side view I will start working with the top view. So, this is this edge that I have drawn there this edge that I have drawn in my top view this edge here very easy I draw the center portion mark this as 19 divided by 2 which is 9.5 I guess draw this edge and dimension. So, always a nice idea to dimension while you are drawing different features of the objects in 3 different views this is 9.5 19 divided by 2 and then I will depict this edge and this edge and then I will complete this loop. So, this part is very nicely visible in the top view what else well this this edge and then this this edge right. So, I already know what this dimension is. So, from here I can measure what this extent is all right. So, these edges would also show up on the right side of the top view and then I would mark the center I would mark the center line and then I will draw this semicircle on the left as well as on the right. Well ideally before I did that I should have marked the vertical center line as well as the horizontal center line both sides to you know depict the center of the semicircle as well as the circle. Nevertheless maybe I am not that patient enough. So, I do that now and with these a centers I draw a circle of diameter 5 22 on both sides. So, this dimension is 114 divided by 2 57 that dimension is 64 divided by 2 which is 32. Now, this is of radius 32. So, I am going to be using a leader now the way I depict this leader is as if I have an arrow this line pointing towards the center of this semicircle at 45 degrees or 30 degrees or 60 degrees. If you have many such circular features here. So, this one is at 45 degrees and then I will draw horizontal and then I will depict this is R 16 scale 1 is to 2 and that one again at 45 degrees on the other side of diameter 11 scale 1 is to 2. So, since the 2 circles. So, it is like 2 times 5 that represents the diameter times 11 am I done with the top view not quite or perhaps I do not know you tell me now I should have dimension this before, but I am dimensioning it now. So, this is about 13 divided by 2 which is 6.5. So, as I said before there would be 2 circular features here also getting represented in the front view. So, I chose to first depict those circles in the top view and then project the corresponding feature on to the front view. So, I project the center line first on both sides and then I project the end points of the diameter of the circle on both sides again. So, since the circle is hidden is going to be shown using hidden lines on both sides. So, this is how nicely these projectors they work you do not have to measure things every time. So, the projectors they do that for you indirectly or implicitly. So, things become lot more efficient. So, always nice idea to keep drawing projectors alongside when you are working with the main drawn. Now, to the right side view of the profile view and now extending these projector lines 45 degree line over here. So, from this side I am going to be seeing this edge it is pretty much this edge I will be seeing the edge corresponding to this surface the verticals you know the extent extreme right and left and I am going to be now seeing this edge right there and this edge right there and then I am going to be seeing this edge right there. Now, like I did for the circles over here I will do the same thing for the profile view first I will project the center line rather center line the profile view and then project the extremes of the circle on to the right side and then again in the right side view or the profile view the circle or the circle of features are going to be hidden I am going to be showing those features using here lines. Now, with these two lines cover only this circle or both circles question right they will be covering both circles what else now this slope is something which would be explicitly visible only the profile view not in the front view nor in the top view. So, you would know the extreme point for this feature here this this location you know which is at this height and then you would also in the extreme point for the slope right there right here. So, this slope is going to be represented by a line a slant line in the profile view. So, starting from here ending up to here there you go anything else that I may be missing well let us see as I said are we missing this line or not this line essentially corresponds to this line in the top view are we missing anything else perhaps not you know, but this example I deliberately made three mistakes I will talk about that something that is quite common amongst you. So, you would do that mistake one I have depicted scaled dimensions, but not true dimensions. Now, what is going to happen by convention I should be depicting true dimensions the reason is because I am mentioning the scale over here 1 to 2. So, of course, any person who is interpreting these drawings he or she would know that the drawings themselves are scaled by half, but he or she would actually see the true dimensions if I depict them number 1. Number 2 look at these decimal points 9.5, 6.5, 6.5, 6.5, 31.5 it is not a good idea to show numbers by means of decimals in your drawing always a good idea to show your drawings by means of whole numbers mistake one that I made you should not make those mistake or that mistake even if you are scaling your drawing you should be depicting true dimensions mistake number 2 look at the way I have dimensioned the drawing the larger dimensions they happen to appear to be closer to the object. Whereas, the smaller dimensions they happen to appear to be away from the object again not a good idea should be the other way around smaller dimensions they should be represented closer to the object and larger dimensions they should be represented away from the object. Mistake number 3 dimensions have been repeated. So, try to depict the information as concisely as tersely as possible do not repeat dimensions. Now, if I do not make these mistake oh by the way I already told you about the leader. So, this would be an arrow which is at 45 degrees well just emanating from the center at 45 degrees to the horizontal and then there would be a horizontal line and above that horizontal line you are going to be mentioning the dimension it is called a leader likewise we have a leader here as well what you mentioned that before. So, this scheme of dimensioning is called the aligned dimension look at the horizontal dimensions we have an arrow with arrow heads on the right and on the left and the dimensions happen to appear to be above the dimensioning arrow for the vertical ones imagine that you have rotated this thing 90 degrees clockwise some like this. So, not only would the arrow get rotated also the number would get rotated. So, the arrow the vertical arrow would look like that arrow heads on both sides and the number is going to be aligned with the arrow. So, if you imagine that this is rotated by 90 degrees anti clockwise the number will be appearing on the left of the dimensioning arrow aligned. That is an example as I have mentioned the number above the arrow for the horizontal dimensions and for the vertical dimensions the number to the left of the arrow, but aligned with the dimensioning arrow. So, you would not want to write 32 as this on the right side or even 32 as you know being aligned to the horizontal line that would not be correct. So, if I correct those mistakes if I bring in smaller dimensions inside the larger dimensions outside, but before that in case of horizontal dimensioning dimension or the number below the arrow is incorrect in case of vertical dimensioning dimension on the right hand side of the arrow is again incorrect mention that just to emphasize. So, if I go back for instance and if I try to correct these mistakes of my mistake 1, mistake 2 and mistake 3 and if I depict all two dimensions number 1, number 2 if I depict smaller dimensions closer to the object larger dimensions away from the object and if I make sure that the dimensions do not get repeated let me go forward my drawing would pretty much look like that. Smaller dimensions closer to the object larger dimensions away from the object all these dimensions in true scale. The fact that I mentioned the scale over here gives the interpreter feeling that these drawings are actually scale by half all right and of course, I have let go of repeated dimensions all right. So, first example in orthographic views this is one of the lab problems I will end this lecture here keep thinking and analyzing until meet next time.