Tips on importing files.
Here are some tips on importing files into OneCNC and the reasons we favour the standards of STEP and IGES.
This is information that we have derived from various sources over time and it may help users understand some of the benefits of a neutral or standard format.
OneCNC has the following import methods:
A. STP (STEP)
STEP-File is the most widely used data exchange form.
This is due to its ASCII structure and it is easy to read with typically one instance per line.
The format of a STEP-File is as defined in a published international standard ISO 10303-21 consisting of a Clear Text Encoding Exchange Structure.
The ISO10303-21 standard defines the encoding mechanism on how to correctly represent data according to a given EXPRESS schema, but not the EXPRESS schema itself.
STEP-Files can also be called p21-Files and STEP Physical Files. The file extensions of .stp and .step indicate that the file contain data conforming to STEP Application Protocols.
The STEP read in OneCNC is not subject to version change and provides a robust standard import from all CAD sources that adhere to the published standard.
STEP translation is the preferred file import and export method in OneCNC. The main reason it is preferred by OneCNC is that it is to an international standard, and does not rely on any other files to function and yearly version free.
OneCNC reads its own STEP files directly and it does not require any other shared files or files in other directories that may be subject to change.
This provides for simplicity of operation without the constraints of yearly versions and or the necessity to become reliant on a particular brand of software because of the reliance on a restrictive file system that may change from year to year.
A user may want to open files years later in other software and an ISO standard can be more assured.
B. IGES
The Initial Graphics Exchange Specification IGES , pronounced “eye-jess” defines a neutral data format that allows the digital exchange of information among Computer-aided design (CAD) systems. The IGES standard which is now 5.3 last published in 1996 and has not changed since.
The official title of IGES is Digital Representation for Communication of Product Definition Data, first published in January, 1980 by the National Bureau of Standards as NBSIR 80-1978. Many documents like the Defense Standards MIL-D-28000 and MIL-STD-1840 refer to it as ASME Y14.26M, the designation of the ANSI committee that approved IGES Version 1.0.
Using IGES, a CAD user can exchange product data models in the form of circuit diagrams, wire frame, free form surface or solid modeling representations. Applications supported by IGES include traditional engineering drawings, models for analysis, and other manufacturing functions.
IGES only seems to be of any problem if the exporting CAD does not adhere to the specifications.
C. VDA
VDA-FS is a CAD data exchange format for the transfer of surface models from one CAD system to another. Its name stands for "Verband der Automobilindustrie - Flächenschnittstelle", which translates to the "organisation of the automotive industry - surface translation format". Standard was specified by the German organisation VDA. VDA-FS is now superseded by STEP, ISO 10303. This is especially provided for the users that do OEM automotive replacement parts. This was commonly used more before STEP arrived.
D. 3DM (Rhino)
3DM Rhino is provided by the developers of Rhino in the interests of file translation between Rhino and other CAD. This is provided through the OpenNURBS . The openNURBS Initiative was founded by Robert McNeel & Associates in January 2000, with the sole purpose of providing CAD, CAM, CAE, and computer graphics software users reliable methods for transferring 3-D geometry between applications.
E. DGN (AusCAD)
The DGN is provided by OneCNC to read the files from the original AusCAD. AusCAD was a previously developed CAD/CAM and the forerunner to now OneCNC.
F. DXF
AutoCAD DXF (Drawing Interchange Format, or Drawing Exchange Format) is a CAD data file format developed by Autodesk for enabling data interoperability between AutoCAD and other programs.
DXF was originally introduced in December 1982 as part of AutoCAD 1.0, and was intended to provide an exact representation of the data in the AutoCAD native file format, DWG (Drawing), for which Autodesk for many years did not publish specifications. Because of this correct imports of DXF files has been very difficult over these years. Autodesk now publishes the DXF specifications, on its website for versions of DXF dating from AutoCAD Release 13 to AutoCAD 2009.
As AutoCAD has become more powerful, supporting more complex object types, DXF has become less useful. Certain object types, including ACIS solids and regions, are not documented. Other object types, including AutoCAD 2006's dynamic blocks, and all of the objects specific to the vertical-market versions of AutoCAD, are partially documented, but not well enough to allow other developers to support them.
While this has helped to some degree almost every CAD on the planet often have their own version of DXF because of so many years of non publication.
OneCNC only imports the ASCII format DXF files.
G. SAT
SAT files are current developed by Spatial. They maintain a current version or release number which is now 19 so therefore there is 19 versions of SAT files. SAT or as it is known ACIS was acquired by Dassault Systemes and is not openly published. This is also a very difficult format for this reason.
I. STL
STL is a file format native to the stereo lithography CAD software created by 3D Systems. This file format is supported by many other software packages also. It is widely used for rapid prototyping and computer-aided manufacturing for this purpose. STL files describe only the triangulated surface mesh of a three dimensional object without any representation of color, texture or other common CAD model attributes. The STL format specifies both ASCII and binary representations. Binary files are more common, since they are more compact.
An STL file describes a raw unstructured triangulated surface by the unit normal and vertices ordered by the right-hand rule of the triangles using a three-dimensional Cartesian coordinate system.
STL is definitely not a preferred file format for importing into OneCNC. Reason being it is just a mesh format and any machining done on this format would have the same roughness as the polygons
OneCNC supports the ASCII and Binary formats of STL.
J. SLDPRT (Solidworks)
SolidWorks files use the Microsoft Structured storage file format.
This means that there are various files embedded within each SLDDRW, SLDPRT, SLDASM file, including preview bitmaps and metadata sub-files.
Various third-party tools can be used to extract these sub-files, although the subfiles in many cases use proprietary binary file formats.
The Structured storage (variously also known as COM structured storage or OLE structured storage) is a technology developed by Microsoft as part of its Windows operating system for storing hierarchical data within a single file. Strictly speaking, the term structured storage refers to a set of COM interfaces that a conforming implementation must provide, and not to a specific implementation, nor to a specific file format (in fact, a structured storage implementation need not store its data in a file at all). In addition to providing a hierarchical structure for data, structured storage may also provide a limited form of transactional support for data access. Microsoft provides an implementation that supports transactions, as well as one that does not (called simple-mode storage, the latter implementation is limited in other ways as well, although it performs better).
Structured storage is widely used in Microsoft Office applications, although newer releases (starting with Office 2007) use the XML-based Office Open XML by default. It is also an important part of both COM and the related Object Linking and Embedding (OLE) technologies. Other notable applications of structured storage include MSSQL, the Windows shell, and many third-party CAD programs.
The file reading is performed by a Solidworks provided document manager not by OneCNC so it is also important to have the correct document manager dll installed in the Solidworks Shared directory. This can also be dependant on operating system and SW version. These read files are stored in the Solidworks Shared directory.
K. XT (Parasolid)
Parasolid is a geometric modelling kernel originally developed by ShapeData, now owned by "Siemens PLM Software" formerly UGS Corp USA, that can be licensed by companies for use in their 3D computer graphics software products.
It is used in many Computer-aided design (CAD), Computer-aided manufacturing (CAM), Computer-aided engineering (CAE), Product visualization, and CAD data exchange packages.
When exported from the parent software package, a Parasolid commonly has the file extension .x_t and .X_B. Most Parasolid files can communicate and migrate only 3D solids and/or surface data.
Parasolid files currently cannot communicate and migrate 2D data such as lines and arcs.
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