Those are really good questions. As I don’t know what you know already I’ll take it right back to basics.
When drawing an object you can either draw a pictorial view (showing 3 dimensions - length, breadth, and height) or you can draw an orthographic, which is a drawing made up of some related views, each looking at a different part, each view only showing 2 dimensions.
For instance you might have a drawing of a house. The front would be drawn in the ‘Elevation’ and would show length and height. The end of the house would be the ‘End Elevation’ showing breadth and height. The view looking straight down at the ground, showing the top of the house is the ‘Plan’ and it has lengths and breadths.
The question about 3rd Angle Projection comes in when you start thinking about where each view should be drawn in relation to the others.
There are two accepted ways to arrange the views - 1st angle and 3rd Angle. If you want to read in more depth then the wikipedia article on Multiview Orthographic Projection is ok, but not as clear is it might be.
In the UK we generally use 3rd angle - this means that the view looking at the left of an object is drawn to the left of the front view, the view from above is drawn above, and so on.
The alternative, 1st angle, is the other way around: The view of the left is projected right through the object and drawn on the right; the view from above is projected through and drawn below, and so on.
Now, your 2nd question:
The 3rd angle symbol helps you to know that the views you are looking at are drawn in 3rd angle, like I describe above. This is just to save confusion. The symbol represents a cone that has had the pointy bit cut off. If you imagine an elevation and an end elevation of that object then you would get this symbol. Similarly the 1st angle symbol is of the same cut cone - but the views are switched round showing it is the other orientation.
It’s quite a hard topic to describe in text but I hope that helps - while the wikipedia article is a little more detailed than you probably want the pictures are still pretty good so it might be worth looking at that.
Good luck Bethany and let me know if I can help you further.
Put simply the different angles change where views are around the Elevation.
In 3rd angle the view from the right is drawn on the right, the view from above (the plan) is drawn above; the view from the left is drawn on the left.
In 1st angle the view from the left is drawn on the right; the view from above is drawn below; the view from the right is drawn on the left.
Architects and engineers need to know which is which so that they can tell what it is exactly they are looking at. The symbol tells them which angle the drawing in based on - because without that knowledge they may confuse the views and the object being built/fabricated may end up different to that which was intended.
August 19th, 2009 at 5:12 pm
I Dont Go To Your School Or Anything But I Was Wondering If You Would Help Me /
I Have Questions That Need Answered.
I Suppose I’ll Type Them Out For You So YOu Can Have a Look At Them.
Q1. Explain What Is Meant By 3rd Angle Projection and Describe Why An Architect Or Engineer Needs To Use It.
Q2. Describe What The 3rd Angle Symbol Represents
PLease Help Me (:
August 19th, 2009 at 5:49 pm
Hi Bethany,
Those are really good questions. As I don’t know what you know already I’ll take it right back to basics.
When drawing an object you can either draw a pictorial view (showing 3 dimensions - length, breadth, and height) or you can draw an orthographic, which is a drawing made up of some related views, each looking at a different part, each view only showing 2 dimensions.
For instance you might have a drawing of a house. The front would be drawn in the ‘Elevation’ and would show length and height. The end of the house would be the ‘End Elevation’ showing breadth and height. The view looking straight down at the ground, showing the top of the house is the ‘Plan’ and it has lengths and breadths.
The question about 3rd Angle Projection comes in when you start thinking about where each view should be drawn in relation to the others.
There are two accepted ways to arrange the views - 1st angle and 3rd Angle. If you want to read in more depth then the wikipedia article on Multiview Orthographic Projection is ok, but not as clear is it might be.
In the UK we generally use 3rd angle - this means that the view looking at the left of an object is drawn to the left of the front view, the view from above is drawn above, and so on.
The alternative, 1st angle, is the other way around: The view of the left is projected right through the object and drawn on the right; the view from above is projected through and drawn below, and so on.
Now, your 2nd question:
The 3rd angle symbol helps you to know that the views you are looking at are drawn in 3rd angle, like I describe above. This is just to save confusion. The symbol represents a cone that has had the pointy bit cut off. If you imagine an elevation and an end elevation of that object then you would get this symbol. Similarly the 1st angle symbol is of the same cut cone - but the views are switched round showing it is the other orientation.
It’s quite a hard topic to describe in text but I hope that helps - while the wikipedia article is a little more detailed than you probably want the pictures are still pretty good so it might be worth looking at that.
Good luck Bethany and let me know if I can help you further.
Mr M
August 25th, 2009 at 9:04 pm
Im Still Very Confused Mr M .
Can You Answer Them Questions As If I Was To Answer Them . I KNow Nothing About It .
And I Need The Info For Tomorrow :O x
August 25th, 2009 at 9:43 pm
iv managed so far but really have no clue about a certain bit .
why do architects and engineers need to use it
x
August 25th, 2009 at 10:44 pm
Ok Bethany, I’ll try again.
Put simply the different angles change where views are around the Elevation.
In 3rd angle the view from the right is drawn on the right, the view from above (the plan) is drawn above; the view from the left is drawn on the left.
In 1st angle the view from the left is drawn on the right; the view from above is drawn below; the view from the right is drawn on the left.
Architects and engineers need to know which is which so that they can tell what it is exactly they are looking at. The symbol tells them which angle the drawing in based on - because without that knowledge they may confuse the views and the object being built/fabricated may end up different to that which was intended.
I hope that helps you.
August 26th, 2009 at 7:24 pm
thanks . i get it now . do you answer any questions ?
September 3rd, 2009 at 8:32 pm
Glad that helped in the end Bethany.
If you have any more questions then feel free to ask here and I’ll see what I can do.