I'm making a piece of armored vehicle, which I plan to send to a 3D print house. Prior to doing so, I union all of the pieces and run it through an STL checker.

During my union-y activities, I came across this curiousity. When I try to union the big piece (selected) to the remaining rivets (the unselected cylinders), the union instead acts like a merge -that is, the two pieces remain (big one and rivet), but now the big one has an indentation where the cylinder intersects.

What up with that?

Hi There,

I found this..., you have to check the surface on the hole.

Hello,

The main model (big piece) is broken(naked edges),.. basically, it is not a solid, so any booleans you make to that will give an unexpected result. With that big piece you can "separate" and then "join" the surfaces back together which will make it a solid.

When making a lot of booleans sometimes the model can become broken, I always check during such to check if the model is still a solid. To do that, you can set up a shortcut key to select solids:- the command is:-

script:moi.geometryDatabase.getObjects().getSolids().setProperty( 'selected', true );

You can add the command in the shortcut keys, and add which key you want(not already in use)

Good tip, Manz!

-Will

Yeah, I have seen a problem where boolean union can in certain situations fail to glue together all the edges of adjacent surfaces. Once you have some edges that are not glued together it will stop your model from having a true volume and it will behave like an open surface.

Like Steve mentions using Edit/Separate and then Edit/Join to repair this problem for now.

I am going to be adding in a kind of "edge gluing" pass to the boolean process to fix this up, I'll try to add that in for the next v2 beta release.

- Michael

Good stuff, thanks!