For reasons that I don’t fully comprehend, there is a deep rooted false myth and legend about exporting STL files, that says that meshes must be joined using Boolean union operations (not only in Blender, people say that for other softwares), in order to export an STL for check repair and slicing.
And if your design is composed of many objects, curves, meshes, with modifiers, sculpted parts, texts, and you have been told that you have to make booleans of all these elements, adding them one after the other, you will soon be confronted with a very cumbersome workflow, and on top of that with a very often failing workflow, making your Blender and 3D printing everyday life a misery.
The best part is that in fact you don’t have to make these supposed union booleans at all. To demonstrate that in practice, I made a tutorial and a design with many elements, many modifiers, different types of beveled curves and meshes, to show a much simpler and efficient way to obtain a checked STL for 3D printing.
I also took the occasion to make a render of the ring, BLENDER 4.4
Gold mens ring with black enamel
Even if maybe for many people properly exporting STL files is an obvious simple task, I got asked about that topic again, by somebody who was obviously told to make the union booleans, again (the first time I read and heard about that myth and legend of the necessity of union booleans in the STL export workflow, was many years ago, so I had hoped that by now, that myth and legend had disappeard). But to my surprise, I saw that people nowadays are still suffering from that very false teaching.
There was a point, some years ago, where a company who did additive manufacturing said their software didn’t always properly calculate the material volume on multiple meshes, which could lead to incorrect pricing. Because of that they recommended combining (boolean) separate meshes. That volume calculating issue went away but it seems the habit did not.
I don’t know that’s the only reason but I do think that is one.
Yes, back in the day, everybody was instructed to do additive booleans, expecting a correct weight calculation (not doing the additive booleans was resulting in the weights of the parts inside of the solid parts to be added, and sistematicaly ending in a wrong total weight).
Also, the STL files resulting from booleans needed a lot of repairing… before being able to give a correct weight. And even so, the weight would be wrong too many times, because additive booleans tended to to leave inside elements that also added to the weight. In some industries, that was not much of a problem, but by example when manufacturing jewels, 1 gram of gold was around 100 USD, resulting in problematic and expensive mistakes.
At the beginning, some reasons I started using Blender, was to check the inside of STL meshes and correct them in edit mode (Blender was really good to navigate inside the meshes and then sometimes work vertex by vertex to stitch or erase faulty parts) Then I started using booleans in Blender, as the results were better in many percentages of the situations. Also the blue/red viewport normals visualization was always very handy in Blender.
But then because I teached a lot and printed a lot, it was all but natural to question the additive booleans process. Then using remesh/decimate became a lot better, because it delivers a one shell mesh, making the weight calculation a lot more accurate, and also delivering already repaired meshes 99% of the time.
That shows that even for weight calculation, using and teaching to use additive booleans, was inaccurate in the first place.
