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How to use OnScale as a CAD Converter

Geometry is the basic building block of any simulation, and while you can create models natively in OnScale, you may also decide to use an external geometry source. CAD tools provide focused and streamlined workflows for creating complex geometry and if you've already designed a model in another tool it can be quicker to use this geometry instead of recreating it in OnScale.


CAD files can come in a number of different formats and file types. OnScale aims to be a flexible simulation tool that can seamlessly integrate into your existing workflow, this includes being able to handle CAD files from a variety of sources. In an update to OnScale in early 2019 we greatly expanded the list of available file formats that you can import. This list now includes:

  • Solidworks (.sldprt)
  • STEP (.step, .stp)
  • Nastran (.bdf, .nas)
  • STL (.stl)
  • Parasolid (.x_t, .x_b)
  • IGES (.iges, .igs)
  • ACIS (.sat)


To handle all of these new file types we implemented a brand new import tool that is more efficient and fully featured. One of the best new features included with this is the ability to export a CAD file with any of the above file types to another format. While OnScale strives to be CAD agnostic there are some CAD and analysis tools that are limited to specific file types. In these cases it is important to be able to convert your CAD files into the proper format, and you can now do that easily within the OnScale tool. This conversion is done locally and does not require any Core Hours in order to complete. Any user can download the OnScale tool and use it for free to convert their CAD files.

In this blog post we'll take a look at how you can start to use the OnScale CAD Converter.

Getting Started

The easiest way to get started with CAD conversion is to import a CAD model into the OnScale Designer mode. To do this, open a new instance of the OnScale Designer mode and click the "Import Geometry" button. In the Import File dialog box you can browse to the file you wish to convert and then click "Import". You should see the CAD file appear in the graphics area:

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Designer Mode Conversion

Converting the file in Designer mode is simple thanks to the new "Export" option in the Home tab of the ribbon. Once the Geometry is imported you can select the "Export" option and then select the file format to export to from the "Save as type" drop down menu. After specifying a name and location for the file, click "Save" to export the model.

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Analyst Mode Conversion

To build this export into an Analyst file, first browse to the working directory where the Designer project was saved. In it you should see another OnScale file with the same name and "cadcom" added to the end of it. This is an Analyst mode input file and can be opened by double clicking it or by opening an OnScale Analyst session and browsing to the file.  In the "cadcom" analyst file you'll find that there is only one command: the CAD command.

This CAD command is new to OnScale and is what powers our new CAD handling capabilities. It allows users to bring in a number of different file formats and mesh them with our default structured mesh, or different element types like general connectivity tetrahedral elements. In this case all we're interested in is the CAD conversion capabilities so we'll focus on the last subcommand called DOUT.  The DOUT command typically is used for outputting debugging information to the console in Analyst mode, but we can also specify that we would like to convert our CAD to another format through it. To do this, we simply replace the * in the second argument with the file extension that we want to export to. In this example we're importing a Solidworks part and want to export to STEP format, so we'll replace the second argument with "step".

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That's it! We can now hit the "Preview Model" button to execute the code and convert the file. When the conversion is complete we'll see the new file appear in the working directory. In addition to STEP files, OnScale also supports export to the OBJ mesh format and Bincad format, with many more on the way. This code can be copied and pasted into any Analyst file to read in and convert a CAD file. 

This conversion functionality is included in every install of OnScale and does not require any kind of submission to the cloud or Core Hour cost. For large CAD files that may require more resources to load up and convert however, these short input files can be submitted to the OnScale cloud to process the conversion with as much memory as needed.

This functionality is now available to try out for free, simply click the "Get Started With OnScale Today" button and sign up to create an account and start simulating.

Get Started With OnScale Today

Ryan Magruder, Application Engineer at OnScale
Ryan Magruder, Application Engineer at OnScale
Ryan Magruder is an application engineer at OnScale. He studied at the University of Southern California, earning a BS in Mechanical Engineering. As part of the engineering team, Ryan assists in developing applications, technical support and software testing.

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