Welcome to Autodesk’s Meshmixer Forums. Share your knowledge, ask questions, and explore popular Meshmixer topics.
Showing results for 
Show  only  | Search instead for 
Did you mean: 

How to remove internal void of thin-walled object

Message 1 of 7
1611 Views, 6 Replies

How to remove internal void of thin-walled object

I downloaded 3ds models of the tanks used for the Space Shuttle from NASA's website. I intend on these rendering these in slices of laser cut cardboard, but unfortunately the models are *too* accurate, and include the vacuous space within the boosters where the fuel would ordinarily go, and so at 1/138 scale the cardboard is too thin along these walls. I exported the files as .obj's, intent on editing them in Meshmixer, but have yet to successfully replace this empty cavity with solid material. I attempted to take the Boolean intersection and difference between the model and an all-consuming shape, such that I could use the leftover solid material to solve my dilemma, but I had no luck with the Boolean solver for either approach.


I'm including the original 3ds file of the External Tank, but the obj file I've been working with provides this error when posting to this forum 

"The attachment's et-source.obj content type (application/octet-stream) does not match its file extension and has been removed."

And when exporting the model from meshmixer as an STL, when attaching the file in this forum I receive this error

"The attachment's et.stl content type (application/ does not match its file extension and has been removed."

Tags (3)
Message 2 of 7

Exporting the STL directly from 3ds provided this: Nothing apparently, as the STL simply disappears when I attempt to post it.

Message 3 of 7
in reply to: bryan.m.boone-1

Tried to convert your .3ds file to a MM import format (.obj as well as .stl) via Rhino and Cheetah3D:

Running EDIT/Separate shells  ends up with many nearly coplanar objects (e.g.: the rocket's tube is composed by several rings) which are very hard to process.

Seems you already tried to upload a native 3DMax  export. 

Maybe you could try to upload that export in a zipped file? 

(or: if that doesn't work: upload it to some file sharing service and post the link to that download)

Gunter Weber
Triangle Artisan

Message 4 of 7
in reply to: MagWeb

Here's the original zip'd folder of the models, the External Tank is under 'ET', naturally. 


Here's the original source of the models


And here's a simplified model offered by NASA, although I still am unsure how to use .3ds files


EDIT: I'm using the sliced cardboard (using slicer for fusion360) in a lesson plan about 3d printing, so I'd appreciate knowing whatever process I need to follow-through, as I'll have to slice both the boosters and the ET (To match a previously made shuttle which was far less troublesome).

Message 5 of 7
in reply to: bryan.m.boone-1

Ok, got the same conversion on these files..


One option is to run EDIT/MakeSolid on this. To get a satisfying result you'll need a very high SolidAccuracy and MeshDensity (I tried 1024 on both values > long processing time and big file size). Now on this result you might run EDIT/SeparateShells to isolate and discard the interior shell finally.


Another option ( not knowing the software you use further on ) which might work is to keep the different unconnected shells and to discard interior surfaces only:

- In SELECT double click on the tip and the end of the tank to select these shells. Hit Y to separate them.

Ohne Titel.jpeg

- Run EDIT/GenerateFaceGroups and pull the AngleThresh to get a single group for the interior surface:

Ohne Titel 2.jpeg

In SELECT double click the interior group to select it and run Edit/EraseAndFill at Replace/FillType = FlatRemeshed:

Ohne Titel 3.jpeg

Do the same on the tip:

Ohne Titel 4.jpeg

Keep this selection and run Deform/Transform. Move the selection to intersect the end part:

Ohne Titel 5.jpeg

On the other part run EDIT/GenerateFaceGroups too (you want to get the interior surfaces to be single groups too). In SELECT: select these groups:

Ohne Titel 6.jpeg

Discard them and rin ANALYSIS/Inspector to fill the holes:

Ohne Titel 7.jpeg

Ohne Titel 8.jpeg

Show the end/tip-part as well, click it with Shift pressed to activate both objects and run EDIT/Combine:

Ohne Titel 9.jpeg


Gunter Weber
Triangle Artisan

Message 6 of 7
in reply to: MagWeb

You are a genius! That worked superbly, thank you so much! Without you, ~2 dozen 5th graders (11 year olds) would've been very angry at me Friday 😅

Message 7 of 7
in reply to: bryan.m.boone-1

Imagine what the kids would have done with a hollow fuel tank! :fire: 😉

Gunter Weber
Triangle Artisan

Can't find what you're looking for? Ask the community or share your knowledge.

Post to forums