Right.
So I want to talk a bit now about units and coordinates.
And this is quite an important thing to kind of get your head around and understand.
Like a lot of things in CAD, it can seem confusing to people at the start, but once you kind of get
your head around it, especially if the coordinates you've always got and moving from CAD system to
CAD system, it's going to work the same and you're just going to know instinctively what's happening,
okay, and how it's working.
So I'm going to presume everyone is starting with no experience whatsoever.
Some of you, it may be obvious the first part of this, just bear with us.
I want everyone to be at the same level.
Okay.
So we're going to start I'm going to pretend you've never seen you've never worked with any coordinates
before.
X and Y means nothing.
And we're going to start from there.
So let's have a look what we've got.
Looking at our blank screen here.
And the easiest way to explain this, if you look down in the bottom left, you will see there's this
kind of right angle shape and it says X and Y.
Okay?
And AutoCAD uses the x, y, coordinate system, X, Y, Z, actually.
But let's not let's forget the Z for now.
So it uses the X and Y coordinate system for 2D drawing, which is what we're interested in at the moment.
And what that means is any if we draw a line, any kind of distance in this direction or this direction
along this kind of axis here is measured in X.
And Appiah and Appiah is measured in why okay now.
People might think y, x, y, y, not millimeters inches.
Well, the truth is, nobody knows what you're going to use.
You might be joining inches, you might be joining millimeters, you might be joining anything.
So it needs a kind of universal way of describing it.
And it uses these x y coordinates.
So X is this direction and Y is that direction.
So if we were to draw a let me delete this.
So if we were to draw a line and I'm going to make this 1000 okay and zero degrees and we have that
line there, this line is actually it's a thousand long, it's actually a thousand in the X direction.
Okay.
So from this point, we've moved 1000 units in the X direction and zero units up.
So if you were to write this down as a coordinate, you would write 1000 comma zero, okay?
And the comma splits up the X and y y.
So.
So I've just I've just drawn up this just to demonstrate.
So if you imagine we have our x ray line running this way and our Y line running that way.
Okay.
And let me just mark those.
Don't again, don't you don't need to be following along here.
I'd rather you just watched and actually grasped it.
What's happening?
Okay, so going this way is X and that way is Y, and as you move, you would go up in value.
So there must be a zero point.
Okay.
And and this is known as zero zero.
It's this symbol we had here down in the bottom left of your corner.
It's where that starts.
That is your zero zero of your drawing.
It's called the origin point.
And it's kind of the origin of your your whole model.
The 00..
So if we were to create a rectangle from zero zero and I'm just going to snap to that.
So this is now from zero zero and this rectangle was let's say it's.
500
by.
400.
Okay, then this point here, if I was to Mark.
This point and write it as a coordinate.
When that coordinate will be 500, comma, 400.
Okay.
So 500 comma, 400.
And if you've ever worked with grid reference and mapping and it's exactly the same principle we have
X, which is along this way and Y and everything, every point is specified as an X and Y from zero
zero.
Okay.
Now, what about if we were to do the same thing, 500 by 400 down here?
Okay, Well, this is zero zero As we move up in this direction, it's plus and this direction, it's
plus it's positive numbers.
But as we move either this way or that way, it's minus.
Okay, So this coordinate down here.
Let's get rid of this would be known.
Well, it's -500 and -400.
Okay, so that's how that coordinate would be expressed.
So this way you get into negative numbers and you might get mixtures of the two.
So if we were to go 300, 200 and draw that there and you might have guessed, but this one would be
so it would be a negative number in this direction.
So it'll be minus, what was it, 300.
But in this direction, we're going up.
So that would be a positive 200.
Okay.
So from 00X direction.
Y direction X always expressed first.
So you know which way that was.
You always know which way that rectangle is going to be because it's always x first minus is down and
to the left and positive numbers are up and to the right.
And that's that's it.
That's a coordinate system.
Okay.
Now if you don't quite get it, you might watch that again.
But what I will say, the best way to learn a lot of these subjects is by using them.
So if you kind of follow along as we're creating things and putting in figures, you'll get it.
And once you get it, you never forget this stuff.
It's like riding a bike, okay?
And if you move on to other CAD systems, this is going to come in handy.
Now, the only thing to bear in mind is we don't actually you've heard of me talking in units and saying,
this is 500 units.
This is.
We're going to be drawing in either millimeters or inches in most cases.
Okay.
But you do need to tell AutoCAD that obviously your drawing is going to look very different.
Your building, your component is going to be very different depending whether it's in inches or millimeters.
Okay.
So you need to tell AutoCAD that unless you do, AutoCAD will just work in what it calls units.
Okay?
So you can change that by typing in units.
Simple as that.
And it will come up with this box and this is where you can set.
So you need to do this.
When you start a new drawing, make sure you're working in the correct units.
At the moment it's set to inches.
So when I have been offsetting these 500 by 400, 1000 by zero, that is all inches.
Okay.
So if it was millimeters, it would be millimeters.
Okay, now I'm going to delete that because that's from an earlier example.
It's not actually the correct size, but if I was to draw that again, I'm going to do is 500 by 400.
Okay.
So you may have seen this box that keeps popping up here and thinking, well, I haven't got that.
Or maybe it's appeared on your drawing, you don't know where from.
It will come up and it will go all the time.
And it's your properties box.
You do use it a lot in AutoCAD and you can bring that up by clicking any object, right?
Clicking and going to properties and it gives you a whole load of information, most of which you won't
understand yet, but.
It gives you.
It does give you the coordinates.
Okay.
The thing is, something like a rectangle.
It has multiple points.
So what I like to do is just create a simple circle snap to the point you want to measure.
And if you click that circle, you can have the center coordinates.
So you can see the center of this is 500.
By 400 K, which makes sense because that's how we drew it.
And if we snap.
If we put one here.
The coordinates of this is -500 by -400.
Okay.
And if we type in units, we're set to millimeters.
So this box is 500 by 400mm.
So when you're creating things, everything will have its own set of coordinates.
And it depends how you're modeling and how you're creating, whether you really need to know them.
Sometimes you'll work with them a lot.
So if you're doing something like surveying where a surveyor is giving you points, maybe you're creating
an architectural layout or landscaping plan, you'll be getting survey points in from a surveyor maybe
saying this is where you know, lampposts are or fences.
We've been out and we've surveyed these and these are the coordinates.
And in that case, it's really important.
And you can just take those coordinates and you can type them in and you can plot things where they
actually are.
Um, in other times, things like mechanical components of map coordinates you will use more in terms
of when you're actually creating an object, a bit like we do when we draw a rectangle.
So.
When we create the size and it's 500 by 300 or whatever, that's that's the kind of way you will use
coordinates in that situation.
The main thing to remember is X always is reference first, which is that way, and the y coordinate
is that way if ever you forget.
If I just close this properties box.
Virus.
We're actually on it, so you can't see it.
But this little icon here will always be at the zero zero Origin.
Okay.
So the main thing to remember is X is in that direction.
Y is up there, which you can check by looking at this and that your origin is zero zero.
And that's about it for now.
That's all you need to know to follow along later on.
If you're getting to 3D, you'll be introduced to another coordinate, which is Z, and that really
is a height value.
So if you imagine looking down on this, if you draw a line from kind of the end of your nose to this
blue square, that would be the Z axis.
Okay?
But you really wouldn't worry yourself with that now until you get well used to working with these coordinates
here.
So.
Yeah, so you know about coordinates now basically, you know about units, you know, to set your units,
whether you're working in inches or millimeters and you know that X is always referenced first in AutoCAD.