Circles

you can draw lines and polylines now and now you’re going to need to know how to draw circles circles are used for many things holes different designs wheels gears and I can go on but you get the idea a circle is very simple in geometry it is defined as all of the points that are equally distant from a single point to draw a circle in autocad use the circle command just type circle on the command line or just the letter C for the command alias or click on it up here in the draw panel on the Home tab in the ribbon
by default you will be asked for the center of the circle as the starting point pick one anywhere then you will be asked for the circles radius enter in 10 units in this case press Enter zoom in or out if you need to know there’s your circle very simple very easy to do you may want to create a circle according to its diameter start the circle command again
pick your first point
and now instead of clicking your point again you can go to the command line and click on the diameter function or option or type in the letter D
remember on the command line when it gives you additional options and they’re highlighted here the blue letter at the very beginning which is typically just the first letter but will oftentimes include the first two or three that’s all you’ll have to type in you don’t have to come down here and click just hit D for diameter press ENTER and not type in 20 we just drew the exact same circle and just in a different way that’s important to know because sometimes you have the diameter and sometimes you have the radius so well if you have one I know what the other is that’s true number wise but oftentimes when you’re drawing an AutoCAD for example if I have this line and this line
need to draw a circle what do I have do I have a radius or do I have a diameter well that depends by start circle and I draw from this endpoint and I want to draw to this endpoint I have a radius not a diameter that’s true but if I want the circle to come to the middle of these two lines I will need the diameter I’ll show you the difference I’m drawing with the radius now
so I will type an end for my end point and draw there that’s my circle let’s start again the circle command type en D for endpoint or snapping to the endpoint of this line it would now hit D for diameter press Enter stretch
I’ll type in end again and go to the endpoint of that line
and there you go I
just found the middle point between these two points and drawing a circle you’ll find situations similar to this while you’re drafting you won’t always have just the radius you won’t know where the center point is you won’t know where the end point is you’ll need to have to draw a circle in a different way well that’s good because you can there are other ways to draw circles inside AutoCAD besides using the center and radius or center in diameter those other methods are drawing a circle by three points about the circle another one is by drawing two points about the circle and then the third option that you won’t have here in this list is drawing it two tangent points and radius say well how will I know when to use what well that’s great we’ll look at an example open up the file that came along with this training video from the fifth project chapter and go to the circle and arcs example file click open
this is a very simple example of some ways to use the different methods of drawing a circle the 3-point option allows you to draw a circle based on three points along the circle so start your circle command
and instead of picking your center point click on the 3p option or type in 3p so let’s say we have these three lines we don’t know where our Center is we don’t know where anything is really all we know is that we need to come from the middle of this line the end of this line and the end of that line and our circle needs to go about those so let’s pick our first point type in mid for midpoint breasts enter
look for the green triangle glyph in the midpoint tag click now type in E and D for endpoint enter and click up here after we get two points AutoCAD will generate a preview of our circle it will always pass through the midpoint here and the end point there
we don’t know the radius or the diameter or the center of the circle but we do know that we need it to pass through the endpoint of this line here press ENTER and there you go we drew our circle very simple very easy to do let’s try it again
type in 3p enter pick one point pick two points and
now the third point
there you go the two-point option works exactly the same way but with one less point let’s draw it
Circle Command
been to pee for two points press Enter now I want to show you a new object snap it’s called quadrant just type in qu a and this will snap to the quadrant of a circle
that means either the left or right most points or the top and bottom most points the center of a circle and draw Plus through it align straight up the y-axis and align straight across the x-axis these are the points on the circle that you will snap to
pick here
and now we can have our circle go anywhere
we can draw a lot of different shapes if you turn on your ortho command just as we did with the line and polyline we will draw this circle either across the Y or the x-axis
there we go press ENTER to start Circle command again and the circle command will always default to the center point radius drawing method so if you want to do anything else you have to tell AutoCAD that you want to do it differently
type in qu a again
and there we go this is a good start to a snowmen now let’s look at the other option that was available to us if you start the circle command you can see we have the 3 P to P and the T TR or the tangent tangent radius just type in the letter T and follow the instructions on the command line
asking us to specify the point on an object for the first tangent of the circle so let’s say we have these two angled lines we want our circle to be tangent to this line and tangent to that line
so you will see that the glyph is up here of a tangent line with the three ellipses that means it will draw it tangential to this line
this line for our second point and now we have to give it a radius let’s give it a radius of five units press Enter and there you go
circle is tangent as you can see to that line here
and it is also tangent to this line that can be very useful when you’re trying to figure out an arc for two different ends you use the trim command just type in TR press ENTER select everything hit enter again
click the circle and then click the line and then the line
and now
created a nice rounded corner for your object
when you type in a radius or diameter for a circle you can either type in the value but you don’t always have to do that you can just pick your point so keep that in mind the three parallel lines that we had here were three units apart but you can pretend you don’t know that just draw a circle
going to erase this one first
Circle command pick an endpoint and then for the radius he can pick the endpoint again
and there you go I didn’t know what that radius was
but they are at 10 units apart you can draw circles in a lot of different ways with a lot of different methods which one you pick will depend on the information you have and what you’re trying to create