I have this happen quite often when I try to union things together.
Roblox is using a CAD solver for their CSG, and CAD hates coplanar intersecting/touching faces, if you remove them from the CSG, and it should union without problems, it’s not a fix :-(, but it is a workaround at least
CAD just means “computer-aided design”
You could argue that Roblox itself is CAD software if it has created at minimum a single piece that escapes the confines of the engine. The CSG solver that Roblox implemented doesn’t work that great when rounding errors happen. Try re-inputting the Position and Rotation values of the bricks and see what happens.
This is an example of a CAD program in action:
Parametric part design with boolean operations, would be a more accurate way to describe CAD, also, keep in mind an acronym isn’t always the complete definition of something, begin reading more on the wiki page and you’ll start to understand what CAD means in more of it’s finer details
[quote]
Parametric part design with boolean operations, would be a more accurate way to describe CAD [/quote]
[quote]
Also, keep in mind an acronym isn’t always the complete definition of something, begin reading more on the wiki page and you’ll start to understand what CAD means in more of it’s finer details [/quote]
Maybe you should follow your own advice 
What I get for basing statements off of experience instead of research xD sorry for all the derailing.
[quote] I have this happen quite often when I try to union things together.
https://gyazo.com/7e56d113a9bfde31084b9eca670a9baf [/quote]
If you still have the place/model repro, can you attach that so we can take a look? Like all other things CSG, it may not be fixed anytime soon.
Also this: Documentation - Roblox Creator Hub
[quote] I have this happen quite often when I try to union things together.
https://gyazo.com/7e56d113a9bfde31084b9eca670a9baf [/quote]
If you still have the place/model repro, can you attach that so we can take a look? Like all other things CSG, it may not be fixed anytime soon.
Also this: Documentation - Roblox Creator Hub
I don’t, I just ended up deleting it.
