CAD Formats

This page contain brief description about the different file formats in CAD

FreeCAD Dsvte format: FCSTD

Best-known Open Source CAD file format

DXF

• Open source interface of AutoDesk
• Also, the documentation for DXF is freely available
• This open documentation was then adopted by other CAD, CNC, and CAM manufacturers as a CAD interface due to its simple structure and overview
• Allows cross-program data exchange even across different operating systems
• Primarily plays a role as interface from and to AutoCAD
• Any current CAD and CNC program can handle the import and export of DXF,
• DXF is the industry standard and the lowest common denominator of all CAD systems
• AutoCAD supports DXF (drawing interchange format) for data exchange with other CAD programs in the current version and usually 3-4 older versions.
• The DXF file format directly supports 2D and 3D coordinates as well as for example lines, arcs and simple surfaces, and other complex geometry elements such as blocks, ARX objects, and dimensions.
• It is possible to create, evaluate or manipulate DXF files with simple means, for example with text editors and almost all programming languages, including Excel's VBA
• The DXF file format, like the DWG file format, has been continuously adapted and expanded to meet the requirements of the respective AutoCAD versions
• Newer versions can also display polygon formats/volume bodies and can be read by 3D visualization programs.

DWG

• Documentation of the file structure is not freely available
• Open Design Alliance documentation freely available
• the format was changed with the introduction of AutoCAD 2000, 2004, 2007, 2010, 2013, and 2018 versions
• The formats designated as DWG 2000, DWG 2004, DWG 2007, DWG 2010, DWG 2013, and DWG 2018 [21] are not backward compatible
• This can be partly avoided by saving in older format versions, the use of external converter programs.
• When using the DXF format, the disintegration of unsupported objects into simpler basic objects must be expected
• The first 6 bytes of a dwg file can be read with a common text editor. You specify the version of the dwg file
• Current files of version AutoCAD 2013 to AutoCAD 2015 start with the header AC1027

IGES (Initial Grafics Exchange Specification) *.igs *.iges

• One of the neutral, manufacturer-independent data formats on the market
• Today's experience shows that there are always problems when converting IGES data. Surfaces are recognized incorrectly or surface edge curves no longer match.
• Starting with version 5.3, IGES also has solid elements and about 40 additional geometry elements and 35 non-geometric elements

STEP (Standard for the Exchange of Product Model Data)*.stp or*.step

• It is the most common format for the exchange of CAD data
• The experience has also shown that converting from this format gives the best results
• It goes beyond pure geometry data exchange (like DXF or IGES)
• Only with the STEP transports assembly hierarchies and basic object colors
• Offers a considerably extended approach compared to the formats mentioned so far, because this standard should enable the exchange and archiving of complete product models according to uniform criteria
• Distribution in CAD software?

STL *.stl

• Describes only the surface of a volume. This surface is resolved into triangular facets
• Do not contain any geometrical elements and can only be changed with special systems
• May be published on Wikipedia (Mediawiki Commons)

VRML files (Virtual Reality Modeling Language)

• It is a description language for 3D scenes, their geometries, illumination, animation, and interaction possibilities including noise sources placed in the virtual environment

Specifications for file format original files

• If possible, Freecad: FCStd
• Alternatively DXF (to allow for the widest possible distribution)

It is a precursor of the X3D standard recommended for this purpose by the World Wide Web Consortium

CAD Softwares	Formats	DWG	DXF	IGS	STL	STEP
FreeCAD	dxf, svg, stl, obj, nastran, vrml, step	yes	?	?	yes	yes
SolidWorks	3dxml, sat, ai, psd, cgr, dxf, dwg, eprt, easm, edrw, hcg, hsf, iges, xmt_txt, xmt_bin, 3D-pdf, prt, asm, step, stl, vda, mts, wrl, xps	yes	yes	yes	yes	yes
Solid Edge	asm, par, psm, dft, x_t, x_b, jt, sat, step, xgl, ifc, stl, pdf, 3D-pdf, u3d, sev, bip, dwg, dxf, xml, model(Catia), catpart,	yes	yes	?	yes	yes
AutoCAD	dwg, dxf, dxb, dwf, plt, dgn V8, dgn V7, sat, iges, igs, step	yes	yes	yes	?	yes
Inventor	ipt, iam, idw, ipn, dwf, dwg, dxf, iges, it, sat, step, stl, xgl, zgl	yes	yes	yes	yes	yes
LibreCAD	DXF, JPEG, PNG, SVG, BMP	?	yes	?	?	?
SketchUp	skp, dae, tif, jpg, bmp, png	?	?	?	?	?