Reduce the size of AUTOCAD File

Issue:

Drawing files in AutoCAD end up being much larger than they should, often with no obvious data in them. Other symptoms include:

• Failure to copy and paste elements.
• Hanging for a long time when selecting text with the properties palette open.
• Drawing file takes a long time to open.

Causes:

This happens when data is imported from a DGN file and the original linetypes were not mapped or were incorrectly mapped to AutoCAD linetypes. This produces a huge object database in the drawing that cannot be purged with the standard tools. Furthermore, if you copy and paste an entity from an affected drawing into another drawing, the entire database is also copied and the problem is spread to the other file.

Solution:

Open affected drawings in AutoCAD 2015 (or a later version) and use the PURGE command. Be sure to enable the checkbox labeled "Automatically purge orphaned data." For AutoCAD 2012, 2013, and 2014, there is the DGN Hotfix.  

AutoCAD DGN Hotfix for AutoCAD 2013/2014 
AutoCAD DGN Hotfix for AutoCAD 2012 

The purge feature in AutoCAD 2015 was added to as a result of the hotfix being rolled into the program, with enhancement (i.e., it is better than the hotfix). 

The hotfix includes two files: 

• DgnLsPurge.dll. Once loaded, it allows you to purge DGN objects using the DGNPURGE command. 
• AcDgnLS.dbx. This keeps the DGN objects from propagating to new files when copying, pasting, or inserting from other files.

Refer to the associated readme files for instructions. Most likely the hotfix files will need to be unblocked in order to work and there is a screen shot about this in the readme. 

To use, enter the DGNPURGE command on the command line in AutoCAD to remove unwanted DGN elements. It gives no feedback until done, so on very big files you will simply need to wait until it is finished, which could take several minutes. After it is done, use PURGE > All on the drawing. 

The large file size problem is partially solved with Service Pack 1 for both AutoCAD 2014 and AutoCAD LT 2014, stopping the propagation of unwanted line types between files. The service pack does not contain the DGNPURGE command, which is needed to clean already affected files. 

Using DGNPURGE on multiple files at once 

There is a third-party plug-in called Drawing Purge that can be added to AutoCAD which will let you purge multiple drawings all at one time. 

AutoCAD LT and the DGN Hotfix 

AutoCAD LT does not have the NETLOAD command which is needed to load the hotfix DLL file, which means the DGNPURGE command is not usable within AutoCAD LT. However, AutoCAD LT 2015 has the enhanced PURGE functionality, so it is recommended to use version 2015 to purge files. As an alternative to the hotfix, converting a DWG file to DXF and then back again, or to DGN and back, or using WBLOCK to write a new file has the potential to remove unwanted DGN elements. 

DXFOUT to remove line types: 
 

1. Open the file with AutoCAD LT.
2. DXFOUT the full file.
3. In a new file DXFIN the file created in previous step.
4. After importing the DXF, generate a new DXF file (DXFOUT).
5. In a new file DXFIN the file created in previous step.
6. Purge all.
7. Save the file.

WBLOCK to remove line types:

1. Open the file with AutoCAD LT.
2. Enter the WBLOCK command.
3. Select the "Entire drawing" option.
4. Click the location button at the bottom-right to name the file and pick a location to save to.
5. Click OK.

DGNEXPORT to remove line types:

1. Open the affected drawing file using AutoCAD LT.
2. Enter DGNEXPORT at the command line.
3. Select V8 DGN under 'Files of type' and click Save.
4. When the Export DGN Settings message box is displayed, verify that the correct seed file and units are selected.
5. Click OK.
6. After the DGN export is complete, open a new template and enter DGNIMPORT at the command line.
7. Select the newly created DGN file and click Open.
8. Verify that the Conversion unit is correct.
9. Click on Mapping setups and select new and make sure Mapping type is Import.
10. On the new Mapping setup, click on Modify.
11. Go to the Linetype tab, change all rows to ByLayer (right-click on the first row which has been set to ByLayer and the select Copy, then select all the rows and right-click > paste).
12. Click OK.

COPY and PASTE

If you have installed Service Pack 1 for AutoCAD and AutoCAD LT 2014, try the following procedure if previous methods fail:

1. Open the DWG file.
2. With the LAYER command, assure that all layers are on, thawed, and unlocked.
3. Copy all objects in the drawing to the clipboard (CTRL+A then CTRL+C).
4. Open a new file and paste all copied objects (CTRL+V).
5. Save the file.