From the course: AutoCAD 2024 Essential Training

Setting drawing units

- [Narrator] We're starting a new chapter now and we're going to start taking a look at how we use our units and our options in AutoCAD. Now we've got a new drawing for you. It's called units&options.dwg. And as usual, you can download it from the library to follow along with this particular video. We will be using a few different drawings in this chapter especially when we talk about units, but for the moment we're using units&options.dwg. You'll recognize it. It's the floor plan with the grids, the dimensions, et cetera and you can see it on the screen at the moment. Now, the first thing we're going to take a look at is our units in our AutoCAD drawings. Now, units are not units that basically you, set so to speak, and everything works fine. The whole idea of units is basically you're setting how the units display in AutoCAD and in your AutoCAD drawings. So you can't say to AutoCAD, oh I want to work in millimeters. Make sure that everything is millimeters for me. It doesn't work that way. You make it millimeters by drawing everything in the model space full size to those millimeters. So you'll notice in the drawing at the moment if we look at the dimensions between the grids. Those are in millimeters. So if you look at something like between grids two and three at the top there in the middle you've got ten three six three, that's 10,363 millimeters, which is 10.363 meters and so on. And basically I've set the drawing up that way and I'm drawing everything full size in the model tab. And that's traditionally how you work, but how do you get those units to display the way that you want them to display? Well that's what we need to work on. Now, the best way to do this is literally to type the word units. And as you start typing, you'll see the units pop up there but also on the dynamic input next to the crosshair you can see the suggestion menu kicks in. So it's picking up every single command system variable and so on, that has units in it. You want the one at the top, the little 0.0 icon units. So if I click on that one there, there's units and it'll bring up the drawing units dialogue box like so. Now what you're doing here is you're setting up your display of your units and how the units operate within AutoCAD. You're not saying to AutoCAD, oh, I want that to be millimeters, please. Doesn't work that way. So let's have a look at how the drawing units dialogue box works. So we're looking at length, so we're talking lines, dimensions, like I mentioned earlier, and how do we want them to display? Well, this particular drawing, I've been working in metric millimeters, so if I click on the down arrow there, the fly out menu appears like normal and I've got five different options. If I work for architectural, you can see it's pretty obvious what I should be working in, which is feet and inches. And I can change the precision of those feet and inches by clicking there on that flyout arrow. If I go to decimal, you'll see, there you go, there's my decimal and my decimal places and 0.00. It's two decimal places. I can go up to eight decimal places in AutoCAD quite happily for precision. Just so you know, AutoCAD measures up to 20 decimal places in the background. You wouldn't know it, but your little processor in your computer is actually calculating distances to that accuracy. Crazy, huh? But it is true. Now obviously I've got other settings there. I could go for fractional. So obviously zero and a quarter, that's feet and inches again. I can also go for scientific. Now if you know what exponential functions are, that basically there is one times 10 to the power of one. And you can see there that I can then go sort of 1.00 times 10 to the power of one, et cetera. So it's all to do with exponential functions and very large distances. Now, I'm going to jump here and go back to decimal, like so. Now, as a rule of thumb, if I'm working in a metric millimeters drawing, I normally leave my precision at two decimal places. Now, I know that might sound a little bit too precise, but that then allows you to have that little bit of coverage where perhaps somebody's drawn something wrongly and you measure it and you go to two decimal places and you don't see something like 15.00. You might see something like 15.01 or 14.98. So that's where that precision is very useful. Now the other one that you've got is your degrees, your angles. Now as a rule of thumb, I would go with double the precision, so I'm using decimal degrees, as you can see. And I'm doubling the precision there because like an angle, like a slice of pie. As it goes further and further out from that vertex on the angle, the distance gets bigger doesn't it, going across the angle at the top. So it's always worthwhile to have that extra precision in your angles. Like I said, I'm using decimal degrees. But there is degrees, minutes and seconds. You've got your gradians and radians there as well. And you've also got your surveyors units as well. Now gradians and radians are basically all to do with a circle and pi and that kind of thing, so just be aware of that. And surveyors units, as you can see, work with points of the compass. So we've got there north zero degrees east. Now, just to make life easy throughout this entire course we are going to use decimal degrees, and the precision is going to be double what we're using for our length here. Now, by default, angles are measured counterclockwise in AutoCAD and arcs are also drawn counterclockwise as well. So the arcs follow this little setting here. So make sure that your clockwise box there is not checked. You do not want a tick in there like that. You want it unchecked like that. And then down here we've got our insertion scale. Now we do cover this a little bit later on and in other courses as well, but ideally, your insertion scale if you're working in metric millimeters in the drawing your insertion scale should also be millimeters. Just before I click on that though, you can see that we can measure all the way up to parsecs in AutoCAD. And for those of you that are Star Wars fans or Sci-Fi fans parsecs are a known unit of measurement. So you'll often hear Captain Kirk in Star Trek for example, say, oh yeah, we're such and such parsecs from the nearest planet. It is a unit of distance. it's a massive unit of distance, but it's there. And we're going from the sublime to the ridiculous when we go back to, oh, we're going to measure in millimeters. But if you're working in metric millimeters in a drawing, ideally set your insertion scale to the same. If you're working in inches, set it to inches. For example, if you're working in feet, set it in feet. We're working in millimeters so let's leave that at millimeters. Now you can see a sample output now, just there. Can you see two decimal places for a distance, four decimal places for an angle. Lighting here, you don't need to worry about. That's when you're working in 3D and setting lighting for visualization and rendering and so on. So you can leave that as it is. One more thing, we're going to click on the direction button. Now, the direction control, I'll just bring that into the center of the screen, basically ensures that to the east is zero and then to the north is 90 and so on. You get that with the 90 degree increments there on the readout. By default, it's normally to the east. So that's your X direction going off to the east at an angle of zero. And that's X equals positive. Going to the left, from the zero, zero origin is where X is negative. And for those of you that have done coordinates at school this is quite easy to understand. I will explain this in more depth as we go through the course, but just make sure that that base angle is set to east and zero, okay. Click on okay there. Click on okay there. And your units are now set in your AutoCAD drawing.

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