You can see the hole is not correct but the model shows as solid. When I export to STL it ends up becoming filled.

You're right..

I fixed it.

I took the edges of a hole, joined them to prepare a new hole.
I deleted the hole on each side.
Then I did a new hole with a boolean diff with your new solid (without the problematic hole) and the circle (from old edges) I had copied before.

Have fun,

Thanks for the fix.

How did you delete the hole? I tried selecting those edges around the hole and hitting delete doesn't do anything.

Maybe like this! ;)
Copy Move by security against only Move! ;)
Select your circle perimeter then Erase it!
And replace the surface if needing...

Hi Charlie, that's probably a bug in something like surface combining but it's pretty hard to figure out where the bug is looking at just the aftermath.

The side walls for that hole has a broken surface where it's only got half the surface that should be there, it looks like this:



It's hard to select broken faces like this, sometimes window select can work but also if you select the top and bottom faces and use Edit > Separate it will get shook out, then select the other pieces and use Edit > Join to glue them back together then you can invert the selection to get that bad piece selected and delete it.

Was this model only built using MoI v4 or did you use MoI v3 for some of it? It's kind of similar to a cylinder combining bug that was fixed in v4 but maybe there is another type of combination that is still buggy.

- Michael

This was entirely designed in v4 Jan 22 build. This appears to be the second time I've done this so there is a good chance I'm doing something very wrong. I will try and recreate the problem and see if I can tell what steps I'm taking that might be incorrect.

Hi Charlie, well I think it's pretty likely that it's a bug. It could be possible that something in particular about how you're doing things makes it more likely to run into the bug though.

If you can send me the model before cutting the hole that was messed up that could help to track it down.

- Michael

I am guessing this is not helpful but I pulled all the components from various saves and dumped them into one file. There are some steps where I don't have the components because I saved over with another version.



From left to right.
1. Copied edges from another object
2. (missing) Extruded along angle path
3. (missing) boolean cut to get wedge shape
4. Using edges from holes boolean (missing)
5. Created larger tubes for partial boolean
6. Decided small holes were not big enough and made new ones
7. Boolean edges (missing)
8. Boolean box off back of model (missing)
9. Added flared edges and back slant boolean (missing)
10. Final model with bad geometry

I think it happens when I do the second boolean diff with the slightly larger holes (step 6). I've tried redoing the boolean a few ways and can't get it to break again.

Thanks Charlie, I will try it over here too.

- Michael