FreeCAD and DWG Import

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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.

Note that at this time, it is not possible to import 3D DWG in FreeCAD. 3D data is embedded as binary .SAT (ACIS) data, a proprietary and undocumented format.

What Do I Need To Be Able To Import DWG Files?

ODA Converter (formerly Teigha Converter)

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

The ODA 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"

FreeCAD v0.19 and LibreDWG

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

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.

Installation

LibreDWG is included in v 0.19_pre appimages[1]

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.

What Are The Alternatives?

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.

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 know that, contrarily to popular belief, 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.

What Can I Do To Help?

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.

Draft

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• Annotation: Text, Dimension, Label, Annotation styles, Annotation scale
• Modification: Move, Rotate, Scale, Mirror, Offset, Trimex, Stretch, Clone, Array, Polar array, Circular array, Path array, Path link array, Point array, Point link array, Edit, Subelement highlight, Join, Split, Upgrade, Downgrade, Wire to B-spline, Draft to sketch, Set slope, Flip dimension, Shape 2D view

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• Draft Tray: Select plane, Set style, Toggle construction mode, AutoGroup
• Snapping: Snap lock, Snap endpoint, Snap midpoint, Snap center, Snap angle, Snap intersection, Snap perpendicular, Snap extension, Snap parallel, Snap special, Snap near, Snap ortho, Snap grid, Snap working plane, Snap dimensions, Toggle grid

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• Miscellaneous: Apply current style, Layer, Manage layers, Add a new named group, Move to group, Select group, Add to construction group, Toggle normal/wireframe display, Create working plane proxy, Heal, Show snap toolbar
• Additional: Constraining, Pattern, Preferences, Import Export Preferences, DXF/DWG, SVG, OCA, DAT
• Context menu:
  • Layer container: Merge layer duplicates, Add new layer
  • Layer: Activate this layer, Select layer contents
  • Text: Open hyperlinks
  • Wire: Flatten
  • Working plane proxy: Write camera position, Write objects state

User documentation

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• Basics: About FreeCAD, Interface, Mouse navigation, Selection methods, Object name, Preferences, Workbenches, Document structure, Properties, Help FreeCAD, Donate

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