The Basics to AutoCAD

Part 10

Today’s tutorial is short and sweet, I hope……..

We are going to take a look at ARCS, for the first time, and CIRCLES, again, as there are different ways of drawing them.

So what is an ARC? An ARC is part of a circle. If you click on the ARC icon , the command line asks for a start point. Once you click in your model space it then asks for a second point and finally an end point.

These points could be anywhere in your model space. Alternatively they could be ends of, centres of or even a point on previously drawn lines. All depending on what is needed for the arc to be completed.

There are several other ways to draw ARC’s. If you go to DRAW in the MAIN MENU RIBBON, click for the drop down menu and then go down to ARC, another menu appears with eleven ways of drawing ARC’s. To go through all of these is really not necessary as they are really too simple to need an explanation.

More often than not you will only use the icon button, which is actually the 3 POINTS arc command. All the other ways of drawing arc’s give you more restrictions and confine drawing of the curve in AutoCAD.

The best way of understanding how to draw arc’s using these other arc commands is just to have a go and put your own points and values into the command line when and if you need to. You should, by now at least be able to understand the basic workings on how to draw almost anything. So these should not pose any problems.

If you have a drawing you can use as a practice drawing try picking different points within the drawing and see how these different commands work. If you do not have one there is a simple drawing for download at the end of this tutorial with lots of points that can be used. It does not matter where you draw your arcs. It’s all about the understanding of how they are drawn that you are looking for.

 

OK, now that you have had a go at that we will look at the CIRCLE drop down in the same place, so go and select DRAW from the MAIN MENU RIBBON and select CIRCLE from the drop down menu.

Again a number of choices a given for drawing circles. Again, the first option CENTER, RADIUS is the one you will probably use more often than not. All the others will restrict AutoCAD with values that you will supply as you draw your circle. If you want use the download drawing go ahead and practice using these commands and see what happens.

 

That’s really all there is as far as the alternative ways of drawing ARC’s and CIRCLE’s. Like I said short and sweet but these need a bit of practice to understand how and why they work.

Next time we will be doing something a bit more involved………..

As usual here are your download files;     the-basics-to-autocad-pt-10     arc-and-circle-01

Here we are again with another AutoCAD installment. Hopefully the lines went well, so this time we are talking Circles and Ellipses……..

Enjoy……..

The Basics to AutoCAD

Part 2

 

So in our first lesson we went over the basic idea of drawing some lines and hopefully you have got that idea mastered. This time we are going for the good old circles and ellipses routine. You know the one where the straight line goes round corners!!!! Well not so much corners just yet. At the end of this lesson we will start to build our drawing that was illustrated in the first lesson, as we will then have some of the components for it.

 

Round and round we go………..

OK standard routine, open your AutoCAD software as you did before. AutoCAD should open to a default dwg, labelled Drawing1.dwg, if it has not and is asking which template you want to open, select acad.dwt.

Drawing1.dwg should now be open and ready to use in your AutoCAD software.

Here we go then, lets draw some circles.

Click on the circle icon in the left hand toolbar, it’s generally about the seventh one down, a circle with a dot in the centre. With your mouse, left click once anywhere on the screen (this is the circles centre point). Move your mouse in any direction away from that point and left click again (this is the circles radius). That is your circle finished.

How simple was that? Can I go now? Oh there’s more………

The only problem is that you are randomly producing circles in various positions and of varying sizes, depending on where you make those mouse clicks. What we need to do is tell the software the position and size of our circle, and that is simple.

Select the circle icon from the toolbar and click in the drawing space, before you make your second click, just type in 50 and press enter on your keyboard. You have just drawn a circle with a radius of 50 units. Well done.

Let’s just go back a step because we still have not told AutoCAD where we want our circle. Take a look at the command line as we draw our circle. When the circle icon is activated _circle Specify center point for circle or [3P/2P/Ttr (tan tan radius)] is displayed. For the time being the part in the brackets is not of too much concern to us. The first part of this line is, it is asking us for a starting point in our drawing space, like 0,0. In fact that would be a good place to draw our circle, so, on the command line type 0,0 and press enter. Now on the command line Specify radius of circle or [Diameter] is displayed. By default AutoCAD is in radius mode, so just type 50 and press enter on your keyboard.

If you cannot see your circle, on the command line type z, then press enter, type e, press enter. Your circle will appear and fill your drawing space.

You will notice that at the centre of the circle there are two arrows, one pointing north and one east with Y and X respectively. This is the WCS icon, World Co-Ordinate System and is positioned by default at 0,0 by AutoCAD. We will cover the use and need for this in a later tutorial, but for now don’t worry about it.

So there you have it a circle with a radius of 50 units with its centre at 0,0.

Right something for you to try…….

Draw these circles with these following details inputting the data onto the command line………..

Don’t forget to start each circle by activating the circle icon from the toolbar……..

45,80              radius 25

60,50              radius 23

75,80              radius 25

90,50              radius 23

105,80            radius 23

75,80              radius 23

45,80              radius 23

105,80            radius 25

90,50              radius 25

60,50              radius 25…  if you can’t see the drawing type z, press enter, type e, press enter.

Well what do you see? It should look something like the Olympic rings??!!?? If not have another go, there is no substitute for practice.

But what if I’m only given the diameter of a circle? Hmmm I thought you would ask that. Simple really, the radius of a circle is always half that of its diameter, so whatever the value of your diameter, your radius will be half that value.

AutoCAD can also draw your circle if you give it the diameter value. If we go back to drawing our normal circle, we first specify its centre point, then in the command line AutoCAD asks for Specify radius of circle or [Diameter]. Rather than enter a numerical value just type d and press enter. This is now telling AutoCAD to draw our circle to a diameter value we are about to give it. Get the idea? Try doing the exercise with the details for the rings but rather than radius values use them as diameter values. Don’t forget type d and enter before you enter your numerical values. See what happens.

 

Ok so that’s the basic principle for drawing circles. How about a squashed one, an ellipse? Well believe it or not they are almost as easy.

Firstly an ellipse is basically a squashed circle as I just said, it is made up from two main constraints, its axis. There is always one long axis and one short one. AutoCAD draws an ellipse by using the values of these two axis.

Select the ellipse icon, usually a couple of icons below the circle icon. Left click in the drawing space this gives you the end of your first axis. Move the mouse away to another random point and left click again, this gives you the end of that same axis. You will notice that now you have defined the length of the first axis the ellipse is shown by AutoCAD, but as you move your mouse around it changes size. Left click again, anywhere away from your last position. This defines the length of the second axis, although you may notice it is only half the width of the ellipse that you are defining. There is nothing wrong with that it’s just the way AutoCAD draws ellipses.

And there you have it, a squashed circle!!! Have a play with drawing them freehand for now and get used to how AutoCAD draws an ellipse.

OK this is all well and good but Mr. Brookes is back asking for an ellipse as part of a design he needs. He has given us its finished size of 350 units by 225 units. To produce an ellipse to exact sizes we need to use the good old command line. So let’s get started.

Select the ellipse icon from the toolbar. Note the instruction in the command line, it/s asking for a start point for one of our axis, Specify axis endpoint of ellipse or [Arc/Center]. Again for now we are not interested in the detail within the brackets. Click anywhere in the drawing space of the AutoCAD window. Once you have done that another command appears Specify other endpoint of axis, now rather than just picking any point we have a definite size to work to. Let’s use the larger size for the length of this axis, type 350 in the command line and press enter. Your ellipse now comes into view on the screen and if you move your mouse around without clicking you will see it changing shape and size in one direction only. That is because we have restricted one axis to a definite length.

OK now on the command line the next request is Specify distance to other axis or [Rotation]. Again we will ignore the detail in the brackets for now. This command is asking for our second size, but be careful here. Before we enter any values read the line again, Specify distance to other axis. AutoCAD is asking for a distance from the edge of the ellipse to the centre of the ellipse. If you move your mouse around a little you will see a line from the curser to the centre of the ellipse. So the finished size we have been given of 225 needs to be halved and entered, type 112.5 and press enter. And there you have it an ellipse to the exact size requested from Mr. Brookes.

Have a practise by selecting your own random sizes and see what happens. As I said ellipses are as easy as circles but just a little more involved when you have the exact sizes.

 

Well now you know how to draw lines, circles and ellipses. As promised we are going to start our drawing now. Below is an illustration for beginning our drawing. Just go and enter all the values via the command lines as you have done previously. For the time being it does not matter where the circles are placed, we will be moving them at a later date.

When you have completed the drawing to this stage you will need to save it ready for next time. Just save the file as you would any other file on your computer. From the file drop down list select save as, in the Save Drawing As window select a location where you want to save the drawing or make a new folder at a location of your choice.

On the File name line give the drawing the name lesson pt2, and be sure that in the Files of type line AutoCAD 2000/LT2000 Drawing [*.dwg] is selected from the drop down tab. By saving back to this version of AutoCAD, if you need to send your drawings out to other people the possibilities are they will be able to open this file. Click Save.

If you want to get a bit more adventurous in the Files of type line, you could use AutoCAD 2000/LT2000 DXF [*.dxf]. This is a Data Exchange File and is used by a lot of other applications similar to AutoCAD.

Some graphic design software can read dxf files as well, like Adobe Illustrator and CorelDraw.

 

Well that’s it for this time round, get it…………. Round……….circles, ellipses………. Never mind. Go and practise your circles, ellipses and lines from before. Hopefully we’ll get you moving and turning stuff next time…………

Here are your downloads to go with this tutorial………

circles      ellipse      the-basics-to-autocad-pt-2

Don’t forget if you have any questions contact us through the blog.