The Center Mark and Centerline tools of AutoCAD

Among one of the many new features of AutoCAD 2017 were the introduction of Center Mark and Centerline tools. With the help of these tools, it’s now fairly easy to add a center mark to an arc or a circle, you can also add a center line with ease using the center line tool.

In this article, I will explain how you can leverage the benefits of these AutoCAD tools to best possible extent, let’s start with Center Mark tool.


Center Mark:

To add a center mark to a circle or arc select this tool from Centerlines panel of Annotate tab. The cursor will change into a Pickbox, click on the circle or arc and press enter to exit the command. You will notice that a default center mark will be added as shown in the image below.


By default, the center mark will span the complete diameter of the circle and it will remain so even when you change the radius of the circle. When the radius of this circle is changed using grips or using properties palette the center mark will adjust its size to the new dimensions of the circle.

You can modify the properties of this center mark using properties palette. Double click on the center mark to bring the quick properties palette, in the bottom of quick properties palette you will find an option for hiding the extension line. Select No from the show extension option to hide the extension line from center mark.


The default centerline extends beyond the circle circumference. You can change the size of this extended length from the quick properties palette or manually using grips of center mark.


As the name suggests this tool will add a center line in between two parallel or non-parallel lines. To add a center line select the Centerline tool from Centerlines panel of Annotate tab and click on the two lines.

The center line will be automatically added in between the selected lines. If the lines are intersecting then the center line will pass through the angle bisector of the lines as shown in the image below.

Center Mark and Centerline

In this case, also the center line will remain attached to their lines and changing the position or orientation of lines will change the center lines as well.

Changing properties of center lines:

The properties of these center lines and center mark such as linetype, linetype scale and linewidth can be changed using system variables as mentioned on this Autodesk knowledge network page. Alternatively, you can also use CHPROP command.

As an example, I will change the linetype scale and linewidth for the current center line. Type CHPROP on the command line and press enter, then select the center line and press enter again. You will see that the command line now shows lots of options related to the center line.

Center Mark and Centerline

Select Lweight from the command line and type 1 and press enter. Select ltScale from command line again and change its value to 1.5, this will increase the linetype spacing to 1.5 times of the initial value. Press enter twice to accept the values and exit the command.

You will see that the new properties will be applied to the center line, you may need to activate the lineweight option from the status bar to see it in drawing area.

Do you have questions related to this tip? Let me know in the comments below.


  1. Expanding the article to include the numerous system variables associated with the new centermark and centerline would help. Since the system variables are tied to the drawing the user’s template needs to be updated for the extensions lines, linetype, etc. for the new commands.

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