Any tools to help with a broken STL

I am trying to print an STL file that I downloaded it and whilst it looks good, when sliced there are some missing details. I have seen this many times before and when I encounter it I usually move on… But I NEED this file as its part of a wider project, so would like to try and fix it.

I loaded it into Sketchup and it looks fine, but after re-exporting I have the same issue.

Looking at the model, there is a ton of internal geometry and I just wonder if there are any essential tools I should be using to help with this kind of situation…

Does anyone have any general recommendations/advice as to how to clean a model to make it printable? Or is this an impossible question?

I could certainly zoom in and manually remove all geometry and re-draw anything broken (and will if I need too), but I just wondered if there were any helpful extensions that I should be looking to use.

Thom Thom’s Solid Inspector2, CleanUp3, TIG’s Solid Solver are three key tools. When you import the STL into SketchUp, set the units to Meters so you don’t potentially risk losing detail because of the small faces thing.

If you share the STL, we might give you more specific suggestions, too.

Cheers Dave… Already use Cleanup3, but will check the others too.

I did hope that Cleanup would remove the internal geometry but it didn’t… The only thing I could make it do was “Merge Faces” which then removed all of the triangles which is a great help.

Whislt I was waiting I manaully cleaned up the model and removed all of the excess geometry and repaired a few holes… And it STILL didn’t work… But then I scaled it 200% and it sliced just fine… Turns out that for this one, the issue was simply “thin walls”…

But thanks for your advice as I have been meaning to get more tools to help with STL cleanup for a while… So will take a look.


CeanUp3 doesn’t know from internal faces. Solid Inspector and Solid Solver can usually deal with them.

Just checked… I also have Solid Inspector2 and use this a lot… But when I import an STL it usually highlights 1000s of gemoetry that it can’t fix… So I normally give up. Is there anything I am missing with that?

Thanks for clarification about Cleanup… I did wonder why it wouldn’t delete the internal geometry… Going to try Solid Solver to see what it does.



Why don’t you let it fix them? Since STLs are always triangulated geometry and there are always more edges than needed for face creation in SketchUp, it’s not unusual to have a huge number of edges that it wants to fix. Run CleanUp3 first, then Solid Inspector2. Let them both do their thing. If the model still requires a lot of repair work, maybe it would be smarter to abandon it and model your own clean one. And remember to import with the STL with the units set to meters first.

I generally do… But often it says xxxxxx could not be fixed…

I just did a test now on the STL before I fixed it and there are 18 Surface Borders and 154 Internal Face Edges that can’t be fixed.

I have a lot of love for Solid Inspector as its helped me with models that I draw… But i have limited success with STL files that I import.

When you say “set units to Meters”, do you mean going into WINDOW -> MODEL INFO -> Units?

Let the extensions do what they can and you’ll have to do the rest. There are always going to be things that require a human to make a decision about.

I guess that’s the downside of using imported STL files or files that other people have made. Generally I find it better to make my own models so I don’t have to clean up problems created by others or by converting file types.

No. In the Import panel click on Options.

Ohhhhhh… I didn’t even know there were options there :slight_smile: Will try that…

So now, after importing in Meters… Solid Inspector is able to ‘fix’ that model… Thats awesome.

Also, I was sure in my tests I saw cleanup3 delete my internal geometry… But it didn’t on subsequent tests… Its now working again.

If I select “Erase Hidden Geometry” from the pull down it does nothing… But if I clean and then tick the box it does…

So I have learned much today… I really appreciate you help