by Dennis Collin
No, this is not a new chapter in a well-known science fiction saga, it is in fact quite an old issue of on ongoing issue with AutoCAD drawings, namely duplicated AutoCAD objects.
Dependent on who works on your drawing or if you receive drawings from external sources, you may find the drawings become a little 'bloated'. IE. the drawings will have excessive layers, block definitions, line types and text styles.
The PURGE command is very useful for deleting unused references particularly things like large site plan, blocks that have been exploded and are no longer needed.
However sometimes you may find the drawing still seems slow and an excessive file size even though the drawing looks comparatively simple. Also you have applied all the usual tricks like ‘Purge’ and ‘Wblock’ but the issue of large slow files remains.
This can often happen after some External Reference Files (XREFS) have been bound to the host drawing or other drawings may have been copied and pasted into the current file by an inexperience CAD draftsperson.
A symptom of the problem can often be found by noticing duplicate objects underneath others. For example you delete a line, but the command hasn't seemed to have worked as the line seems to remain. In fact the command has worked it is just that there are several lines in the same place making the drawing more complex than it needs to be.
Overkill, also known as Delete Duplicate Objects is a very useful tool in cleaning up drawings prior to issue or during key stages of a projects. Ensuring that the drawing does not have duplicate objects in the same place, that happens to be on the same layer (although options are available to change this if desired.) It used to be an additional command found in the Bonus, later Express tools as an optional install within the AutoCAD setup process. However in recent years the command has been relocated into the standard AutoCAD command toolset.
To run the OVERKILL command you can either access the command by typing it in or locating the Overkill button in the modify panel on the ribbon
After running the command you need to select the elements in the drawing. (The ALL function at the select objects prompt works well for most situations.)
The command provides a comprehensive dialogue box on how the function is to deal with duplicated or cloned objects, if in doubt use the default settings.
Clicking OK will delete the spare elements and a number of items deleted or optimised will be reported on the AutoCAD command line.
As well as deleting duplicate objects, overkill also optimises Polylines (by removing unnecessary vertices). It also 'welds' or joins co-linear lines that overlap.
Overkill will ignore duplicate elements IF they are located on different layers, colours or other settings unless instructed otherwise. If the file still seems slow after running Overkill it may be worth checking the drawing for exploded hatch, deleting the elements if appropriate and reapplying hatched areas.
In summary then the Overkill function is a very useful tool in ‘cleaning’ AutoCAD drawing files. It has on occasion reduced file sizes by up to 90%. But even smaller reductions are useful when archiving drawings to real media, stored in the cloud or transmitted via email.