CAD File Formats

The OpenFlexure project is currently build using OpenSCAD, which is a script-based parametric CAD package. This enables one set of source code to create all the different versions of the microscope, which is really helpful as it means any improvements to one version get automatically included in the other versions. It's also a completely free and open-source solution, which is fitting for an open source project.

A common request is for editable files for use with a commercial CAD system, for example SolidWorks or Autodesk Inventor. Unfortunately, this is surprisingly difficult to do. OpenSCAD will export STL or CSG files, which represent the geometry that's been created. However, this misses out on all the parametric information - the underlying maths that enables one set of source code to create multiple different versions of a model. So, while it is possible to get a mesh or a volume into e.g. SolidWorks, it represents only a snapshot of the output of the script, not the whole project. That means that when the main project is updated, anything that's been modified in SolidWorks will be out of date. Similarly, if you make an improvement with another CAD program, it's hard to re-integrate that into the project without re-doing it in OpenSCAD.

We don't want to exclude people just because they don't know how to use OpenSCAD, and so if you would like to play with the designs in the program of your choice, feel free - and if you improve it, please do raise an issue on GitHub, and attach some STL files, and with any luck your improvements will be re-implemented in the main project. However, there are at present no plans to move the project out of OpenSCAD. FreeCAD is a promising option, but we've not had time to really try porting the microscope, and the geometry generated by OpenSCAD is currently too complicated for FreeCAD's OpenSCAD importer to cope with.

One compromise could be to separately export different bits of the microscope body as individual STL files (e.g. the actuator core, the stage mechanism, etc.) - there isn't currently a way to do this, but it would be nice to have one. If you can see a sensible way to do it (ideally automatically, rather than manually commenting stuff out) we'd love to see a suggestion from you!