Dimensions

what is a drawing without dimensions and just a bunch of lines I guess but dimensioning a drawing properly is essential there are many tools in AutoCAD to help us annotate our drawings dimensioning is the process of adding measurement annotation to a drawing let’s open up the dimensions example drawing
you can create dimensions for a variety of object types in many orientations linear dimensions can be horizontal vertical aligned rotated a baseline or a continued dimension which is a chain dimension dimensions can be associative and non associative or exploded associative dimensions adjust to changes in the geometric objects that they measure I recommend that you always use associated dimensions especially if you are placing your dimensions in paper space I’ll show you some examples here these dimensions he
that I’m selecting
in paper space dimension associativity defines the relationship between your objects and the dimension object there are three types of associativity between geometric objects and dimensions now this gets kind of technical here and I apologize for that but it’s important to know the difference because when you run into drawings that aren’t using these features it can be difficult to work with dimensions associative dimensions automatically adjust their locations their orientations and measurement values when the geometric objects associated with them are modified so your dimension will follow the line dimensions in the layout may be associated to objects in model space the dim associate system variable di M a SS OC
should be set to two there are three settings for this system variable zero which is off one and two when it’s set to two the dimensions will follow the line work so if you shorten a line your dimension will move accordingly and will automatically be updated a non
associative dimension which is set to one will not change when the geometric objects are modified and if it’s set to zero then it’s an exploded dimension that means that it’s just a collection of separate objects like a line or text a block for the arrowhead etc it’s not a dimension object therefore if you want to edit that dimension you have to delete each individual piece and recreate it or move each piece as if it were line work dimensions have several distinct elements to them
they have their texts
lines arrowheads
and extension lines all of these can be controlled defined and altered through the dimension styles or through the properties manager
let’s go to this no dim tab just click on it it’s the same line work as in the dimension tab here and in the Styles tab here only there are no dimensions creating a dimension is actually very simple there are several ways where you can get to the different dimensions if you’re on the Home tab in the ribbon you can go to the annotation panel the annotation panel is sort of a short and condensed version of the annotate tab you can create dimensions right here click on the flyout arrow and you have a linear dimension which will lock the dimension in a horizontal or vertical orientation essentially it will give you your X or Y distance the aligned dimension will give you the distance between two points regardless of its rotation or angle the angular dimension will give you the angle of your objects you can do an arc length a radius the diameter an ordinate point and you can jog your dimension as well especially on a radius so in order to create any of these just pick one we’ll start with the aligned now when you dimension you want to make sure you’re using euro snips especially with your dimensioning in paper space so turn on your Oh snaps or you can always type in endpoint let’s pick down here
type in end again
click up here
and there you go this is 100 feet long this is a pretty big piece of steel or wood or something here but that’s okay the unit’s really at right now are not as important we’ll go over how to set units and dimensions later but that’s it you pick two points
another point in your second and then you pick your point where you want your dimension to be shown it’s really that simple
now let’s try a radius
you can only put a radius or a diameter on an arc or a circle obviously a line doesn’t have a radius so you just pick and while you’re putting your dimensions in you can use your scroll wheel on your mouse to zoom in or out click and hold it to pan around
and just place your dimension wherever you want it to be and that’s it dimensions are quite simple to put in once you have everything set up the way you want them you start your dimension command pick your first point pick your second point and then pick your location editing dimensions that can be a bit tricky if you want to edit text you can either type in edy press ENTER and then select your text
press escape to get out
you can double-click the dimension of course here I missed and went to paper space if that happens come down here to the bottom and click on this model button if that model button isn’t there then scroll out and double click somewhere out here
and as you see
can be tricky that’s okay that’s why we have the IDI or edit command now to edit the text you just type in whatever it is you want it to be
it works just like your text editor you have a lot of different options up here and you can even delete the text that is the actual dimension when you’re finished just click outside of your text somewhere
if you want your dimension back use the less than and then the greater then you can see the actual dimension or the actual measured dimension is highlighted that’s how you’ll know that someone just didn’t type in the number which you can do it’ll show up the same way here in your drawing but when you’re in the text editor
it’ll be highlighted letting you know that someone just hasn’t overridden the dimension so that’s it in a nutshell we’re going to look at different things in different ways and in more detail here in the next few sections