Outer shell issue combining two solids

I have two separate solids that I am trying to combine using outer-shell. Depending on how the two solids are positioned against each other it will create reversed faces and does not delete the interior. Does anyone have any insight into why this is happening. Thanks for the help.

How about uploading the SKP file so we can see what you are working with?

Sorry thought i had linked it.


You need to make the file accessible. Currently it shows that permission is required to download it. How about just uploading it here?

its 25 MB which apparently is to large to allow me to upload. I’ll see what I can do.

If you are trying to combine them for 3D printing, you can just leave them as two separate intersecting solids. Most slicers will handle them just fine. This is also an advantage if you want to change the angle between the two solids, since you can just move or rotate the groups or components.

On the other hand, if you need to combine them to get a total volume or some such, please ignore my suggestion.

The two solids are each a collection of flat planes. Depending on their orientation, the planes may intersect in a way that produces a tiny edge that doesn’t get created. This leaves a hole in the single outer-shell object. A clever work-around suggested by @DaveR (called “The Dave Method”) will probably fix your issue. This picture will hopefully help explain what I’m talking about:

Note the object on the left and how the hidden lines meet exactly. This is a happy union. The piece on the right has a “wavy” intersection created by uneven alignment between the two. Your particular problem is similar and compounded by the curved cylinders intersecting.

unfortunately I need to make it a solid because I am looking to eventually convert this into a CAD file that could be used to CNC a mold.
It sounds like I need to make sure the lines on each of the solids match up in order to avoid edges being created, which is a little difficult given the shape of the two objects. Thanks for the info.

Not necessarily but you may need to work at a larger scale.

Try The Dave Method.

That is really cool I typically just do grouping and haven’t used components much but this will definitely help working on the small scale that I am.