FreeCAD and DWG Import

Why is it hard to support DWG Files in FreeCAD?
The DWG format is a closed source binary file format that is not directly supported by FreeCAD. It requires an external 3rd party file converter to first convert then import the conversion into FreeCAD for use.

LibreDWG
GNU LibreDWG is a free C library to handle DWG files. It aims to be a free replacement for the Open Design Alliance Drawings SDK libraries. Be aware that, since libreDWG is a work-in-progress, it lacks support for some DWG entities.


 * homepage: https://www.gnu.org/software/libredwg/
 * license: GPLv2-or-later
 * optional, used to enable import and export of DWG files

Installation Windows
LibreDWG can be configured to work on Windows by downloading and unzipping the appropriate pre-compiled windows binary and adding the folder to your Windows versions system path.

Installation Linux/Unix systems
git clone https://git.savannah.gnu.org/git/libredwg.git cd libredwg mkdir build cd build cmake .. make make install (or use checkinstall, or simply locate & copy the dwg2dxf utility to your executables path, it will be then autodetected by FreeCAD)

Installation openSUSE
To prevent problems you must use LibreDWG package compiled for the installed openSUSE OS distribution. LibreDWG is typically installed with YAST (abbr. Yet another Setup Tool), the Linux operating system's setup and configuration tool.

The more experienced user first gets an overview of possible packages provided. Note: openSUSE has several options to choose from when downloading LibreDWG. To view these options, visit Survey of provided LibreDWG packages on openSUSE.

For e.g. Intel or AMD 64-bit desktops, laptops, and servers the (x86_64) release is the one to select. So libredwg0 and libredwg-tools are of the right choice to install.

It is recommended to grab the binary packages directly. Then select the correct distribution for your installed openSUSE OS.

In any terminal/console (root rights required) the installation will be carried out with:

ODA File Converter

 * homepage: https://www.opendesign.com/guestfiles/oda_file_converter
 * license: freeware
 * optional, used to enable import and export of DWG files

The ODA File Converter is a small freely available utility that allows to convert between several versions of DWG and DXF files. FreeCAD can use it to offer DWG import and export, by converting DWG files to the DXF format under the hood,then using its standard DXF importer to import the file contents. The restrictions of the DXF importer apply.

Installation
On all platforms, only by installing the appropriate package from https://www.opendesign.com/guestfiles/oda_file_converter. After installation, if the utility is not found automatically by FreeCAD, you might need to set the path to the converter executable manually. open Edit → Preferences → Import-Export → DWG and fill "Path to Teigha File Converter" appropriately.

For more detailed instruction see this tutorial.

Usage
The program may be used with the command line interface or the graphical interface. Be sure to convert the DWG files to an ASCII-Format.

Command Line Format is:
 * 1) Quoted Input Folder
 * 2) Quoted Output Folder
 * 3) Output_version {"ACAD9","ACAD10","ACAD12", "ACAD13","ACAD14", "ACAD2000","ACAD2004", "ACAD2007","ACAD2010"}
 * 4) Output File type {"DWG","DXF","DXB"}
 * 5) Recurse Input Folder {"0","1"}
 * 6) Audit each file {"0","1"}
 * 7) [optional] Input file filter (default:"*.DWG;*.DXF")

Example for Linux

ODAFileConverter "/home/dwg-data" "/home/dxf-data" "ACAD2010" "DXF" "0" "1" "test.dwg" The second number (audit) needs to be 1 otherwise it fails

Example for Windows

"C:\Program Files\ODA\Teigha File Converter 3.08.2\TeighaFileConverter.exe" "Path-To-Input-Directory" "Path-To-Output-Directory" "ACAD2010" "DXF" "0" "1" "Name-Of-A-Test-File.dwg"

QCAD pro

 * homepage: https://qcad.org/en/qcad-command-line-tools#dwg2dwg
 * license: commercial
 * optional, used to enable import and export of DWG files

QCAD is a well-known open-source DXF-based 2D CAD platform. It also offers a paid pro version, which is basically the open-source version plus support for the DWG format. When buying the pro version, QCAD also includes a DWG to DXF conversion utility that can be used by FreeCAD.

CADExchanger Workbench
Installing the CADExchanger Workbench allows for working with DWG files through integration with the paid commercial file converter product CADExchanger. Just follow the instructions in the GitHub repository. You can discuss this workbench on its forum thread.

At the moment, the CADExchanger way is the only one that allows to work with 3D DWG files, by converting them to other 3D formats.

DoubleCAD XT
There is also DoubleCAD XT (https://www.turbocad.com/content/doublecad-xt-v5). The program is free for personal and commercial use. It requires a free sign-up to receive an activation code via E-Mail. This Program is windows-only. Note: it does not seem to have been updated for years.

NanoCAD 5.0
There is also nanoCAD 5.0 (https://nanocad.com/products/nanoCAD/download/). The program is free for personal and commercial use. It requires a free sign-up to receive an activation code via E-Mail. This Program is windows-only.

Export your AutoCAD files in friendly format
Exporting your AutoCAD files in a more FreeCAD friendly format, like DXF R12 or R14, SVG, and if version supports it, IGES. All are better alternatives to the DWG format when using FreeCAD.

It is important to note that there is no difference between the contents of a file saved in DWG or DXF formats, provided it is the same version (ex. DWG 2014 vs. DXF 2014). Both formats are maintained by Autodesk, and they both support exactly the same features. The difference is that DWG is closed (machine-encoded) while DXF is open.

Promote the use of alternative formats
Simply put, stop accepting work done in DWG format. In practice, this is often easier said than done. Still, it would not be bad practice for users and supporters of FreeCAD to avoid and reject the DWG format whenever possible.

Use the LibreDWG library and file bug reports
In development version as mentioned above you can switch from the proprietary ODA Converter to the free software LibreDWG library for DWG (and DXF) files. Please do this and report any problems you encounter.