FreeCAD Help & Showcase

Good tutorial

Personaly when I need to rework STL file, I prefer re-design the whole part in the part design workbench.

I use the STL to define datum plane/point/line, so the final part is way more lighter, and I can easily modify the part.

and the main point for is that the cylinder are real cylinder in this case.

Thank you very much.

Well said, polygons for circles can be very annoying to work with, especially if trying to fillet an edge...