autocad 2017autocad 2017

The AutoCAD release last year included enhancements to its dimensioning capabilities, allowing users to create multiple types of associative dimensions within the same command and then place them all on a specific layer. AutoCAD 2017 takes dimensioning a step further with its tools for creating and editing centerlines and center marks, associative objects that refer to centers of holes and axes of symmetry.

Center mark and centerline menu

Since their introduction into AutoCAD decades ago, the evolution of centerlines and center marks has remained stagnant. Both were created independent of the surrounding geometry, so once they were drawn, they were done. The updates for AutoCAD 2017 finally changes the functionality of these features for the better.

Centerlines and Center Marks Stay Consistent in AutoCAD 2017

Both the Center Mark and Centerline tools are available in the Annotate ribbon tab. The Centerline tool creates centerlines that remain associated with lines and polylines. The Center Mark tool creates center marks that are in association with a circle, arc, or polygon arc, depending on where it is placed.

Here’s where the evolution is obvious: When the associated objects are moved, the centerlines and center marks update along with it.

For example, changing the angle of one of the objects associated with a centerline would rotate the centerline to an angle halfway between the two angles of the associated objects. Simply moving or changing the size of the object will relocate or size the new center objects.

In the view below, you can see that the centerlines and center marks updated automatically as the grips are stretched.

Center lines and center marks updated automatically

System Variables for Controlling Centerlines and Center Marks

The CENTERDISASSOCIATE command disassociates centerlines and center marks from objects, and the CENTERREASSOCIATE command associates them again. And that’s only the tip of the associative iceberg. Below is a breakdown of the system variables that control the appearances of centerlines and center marks.


CENTEREXE controls the length of the extension line beyond the object for centerlines and center marks.



CENTERMARKEXE determines if extension lines are created for center marks.



CENTERCROSSSIZE controls the size of the central cross for center marks.



CENTERCROSSGAP controls the gap for the extension line between the central cross and the extension lines of center marks.



CENTERLTYPE sets the linetype for centerlines and center marks.



CENTERLTSCALE sets the linetype scale for the centerlines and center marks.


CENTERLAYER sets the layer that centerlines and center marks are created on.


Centerlines and Center mark objects also have grips that allow editing, and the multi-functional grip menu offers additional controls.

multi-functional grip menu

The Properties palette will allow you to see and edit centerline and center mark properties.

properties centerline center mark

The CENTERRESET command will reset the extension lines of a center mark or a centerline object back to the current value of CENTEREXE.

Autodesk gradually irons out the kinks with each new update to AutoCAD. Check out our previous blog entry to learn how the new Autodesk desktop app helps you stay on top of security patches and updates for Microsoft-based Autodesk products. Contact us if you want to learn more about controlling centerlines and center marks.

We’ll be keeping this blog updated through the year to track all of AutoCAD’s evolution.