I overlap my Parts by .01 to get rid of that issue. I haven’t seen it that obvious before, usually just .001 stud or so.
Either that or don’t Union Parts together, just Negate the corners off for something like that first example.
Maybe it has something to do with floating decimal errors for Position of the Parts?
I tend to go with the Negating option. Sometimes with adding Parts to each other, even if you get the edge to edge surfaces lined up or overlapped, the flat “top” surface still produces a visible line because the 2 Parts aren’t at exactly the right level.
You can fine tune Position by using .0001 stud increments in the Properties window, but it isn’t visible unless you are right next to the Union or the light shines off it just the right way.
I was attempting to make a bowl from unioning through negation however it seems be all kinds of messed up.
I go about it the regular way, starting with a single sphere; http://prntscr.com/kotc8d
I then copy the sphere and resize it by .125 on all sides with the intent of negating it to make the sphere hollow; http://prntscr.com/kotcq4
When I try to make the inner sphere a negative part it moves itself slightly, offsetting as you all are saying. So I undo it, copy the position of where it was supposed to be at, and paste it when I make it a negative part again so that it is in the center of the sphere I want to make hollow. When I finally union the inner sphere(negative part) and the outer sphere, this monstrosity presents itself before me…; http://prntscr.com/kotepl
At this point, I’m at a loss. Absolutely baffled. So I undo to before I union both parts and I move the outer sphere to unveil the beast; http://prntscr.com/kotf5r
Now this, I can say with a indisputable degree of certainty, is something I have never seen before.
Disabled CSG V2, it solved the sphere problem. However it wont even let me union the set of bricks I was having my initial issues with. It wont let me union every part without; http://prntscr.com/kotq5x