Towards STEP components

Hi all,

Some may remember the topic about STEP files. Unfortunately, OpenSCAD being entirely mesh based doesn’t give nice solid object in a STEP file that can then be adapted in other CAD.

I have found a nice video that explains some methods for editing stl files.

Simple example:

If we take the electronics drawer and import it into FreeCAD we get this:

A somewhat uneditable object, but if use the “Part” workbench. And select from the menu, Part->Create shape from mesh. Then select the “Sew shape” tick in the popup and click next we now have this monstrosity:

Not the progress we were perhaps hoping for? However, by next selecting Part->Create a copy->Refine shape, we start are able to combine all the triangles on the flat surfaces:

Now we are starting to get somewhere! We still have a lot of triangles for anything that is curved. Before we go any further we need to. Create a solid with Part->Convert to solid.

At this point we could export the STEP file in a more useable state. Or in FreeCAD we can go to the “Part Design” workbench, and move the solid into a body. We can then play around doing some cuts and extrudes.

For example it isn’t too much work to convert the mounting points at the front into real cylinders. This can be done by making a sketch of some circles off 3 points on the mesh, cutting away the existing mount, extruding the circles (before pocketing the screw holes back through). As you can see we can now select the cylindrical face.

What about the main body?

This process doesn’t work for the main body. There are a number of mesh issues we hit with the microscope. The mesh analysis tool in FreeCAD actually makes a mess of repairing them. Even if I use ADMESH to fix the STL first FreeCAD still claims that there are a lot of mesh problems, even when ADMESH says there are none:

I think if we can get past these mesh problems we can do something similar for the main body, this would make it much easier for people to adapt the design for their needs.


That is interesting. Does the FreeCAD interface actually give us useful information to help to find the original cause of the mesh errors by showing where they are in yellow/red?

Thanks very much for this - I think a lot of people will appreciate that tutorial, including me :slight_smile:

Yes. The yellow and red bits are the errors. You can also turn off wither it displays the different error types. To work out what type of error it is. I think we also need to know why admesh thinks there are no errors after fixing, yet FreeCAD thinks there are errors.