AutoCAD Tips & Tutorials

Create a circle with a width

There are various reasons that you might need to create a circular object with a specific width, such as matching cable widths, or showing cross sections. I've come up with 3 ways to go about this. The right one for you will depend on your needs.

Fit a polygon

An excellent method uses the POLYGON command and fits it using the PEDIT command:

Create a 4-sided polygon, using the POLYGON command.You can circumscribe or inscribe it. At the prompt for the radius, enter the radius of the circle that you want. I used a radius of 4. Of course, this creates a square.

Start the PEDIT command, select the polygon, and use the Fit option. Presto! You have a circle. Then use the Width option and specify the width that you want. (I used 0.25.) The result looks bigger, in this case, but still has a the same radius of 4.

Use a donut

The DONUT command is very old, but can give you the result you want, especially if you know (or want to calculate) the inner and outer diameter. (Try typing doughnut on the command line. It works!)

Start the command, and specify the inner and outer diameters. Because I wanted the same result as for the previous method, I used 8 and 8.50. Then specify the center. Press Enter to end the command, because you'll be prompted to place other donuts, and you don't want too much sugar at once.

Use a lineweight

You can use the CIRCLE command and give it a lineweight. This method has a few problems:

• The object only looks thick; if you change the circle's properties, it no longer has that lineweight.
• Lineweights are listed in millimeters by default. (This is because lineweights were originally designed for use with carousel pen plotters, and the width of plotter pens is generally measured in millimeters.) If you're working in inches, this may make calculations difficult. However, you can change that default, using the LINEWEIGHT command. In the Lineweight Settings dialog box that opens, change the setting to inches.
• If you turn off the display of lineweights (the LWT button on the status bar), you lose the thickness.
• If you want all of your properties to be defined in your layers, you need to create a special layer for your circle.

On the other hand, this may be simple for you. Just draw a circle, select it, and enter the lineweight in the Properties palette (Ctrl+1).

Trim the circle in half and use PEDIT

Jon e-mailed me with the following additional solution: If you use a circle and trim it in half, pedit that, you can then give the resulting pline arc thickness, mirror it and pedit join it into a circle.

I was also able to use the JOIN command to join the two circle halves.

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