8 Jun 2020

Working with large STL files

Another post about 3D printing, I haven’t had enough time to use my 3D printer has much has I’d like so I’m learning a bit slowly. A problem I have encountered several times is that I find a great model on thingiverse but they always provide STL files only, which I would say is like machine code in software, the end result, what I'd like is the source code so I can modify it more easily.

Usually CAD softwares like OpenSCAD or FreeCAD can do some work with STL files, but in case of large files, it becomes much more complicated. For mother’s day I was tasked to do a cachepot looking like a Buddha’s head. I found KFix’s Buddha, which is a restored version of prk_mek’s head of buddha:

To transform that to a cachepot I need to cut the top of the head and then dig a hole in it. When opening it with FreeCAD, it was quite slow (my computer is 9 years old… and FreeCAD seems to be quite mono-threaded) and at some point when working with the file, FreeCAD kept crashing, so not going anywhere here.

I tried with OpenSCAD, I did manage to do the modifications I wanted, but it failed to calculate the final rendering, so another failure.

I did what I didn’t want to do: install a proprietary software. Even worse, a cloud-based one. It seems that a lot of people are using Autodesk’s Fusion 360, and it looks like a very good tool despite those 2 main issues. But again, I imported the STL file then Fusion 360 told me it's limited to 10 000 faces mesh files, and this file has over 200 000 faces… so nope, not better (and now I keep receiving emails from Autodesk despite not giving them my consent for that… 😡).

So how are people doing with those files? Then I realized that the softwares I was using are meant to build things, not to modify mesh files. So I turned to Blender, a very well known software used to make animation movies (there are other softwares specialized in working with mesh files). It's a different kind of software, so new things to learn but it had no issues whatsoever with a big STL file and I did manage to get what I wanted: