I have this simple mesh I am trying to CSG together:
It’s very very simple: every part but one is on a 0.1 stud grid. And yet, it will not CSG together nicely. I get all sorts of odd-numbered errors, missing faces, smoothing errors, and separate meshes where the engine has decided that it isn’t going to combine two coplanar parts.
My challenge to you is: union all the parts in this coupler such that the final mesh has an orientation that is a multiple of 90 degrees in all axes without any internal faces.
Avoid building on a 0.1 grid with CSG. The only way to get the system to work reliably is to only use numbers that can be represented in floating point for sizes, positions, and rotation matrices.
As stated above, build in larger scale!
Also remember that keeping something “on a grid” not necessarly will actually do it due to floating point. You can try this tutorial to “fix the position” of parts. In some cases it might not work as there are several reasons for an error to appear
Since you’re doing this on a rather small scale, you should move the parts closer to the origin of the workspace (0,0,0), this’ll make it more precise.