STL Importer fails to close small polygons

I am seeing a problem using the STL Importer with Sketchup Pro 2016. Specifically, numerous regions of small polygons are not filled:

I can manually re-draw the lines between the existing vertices to close the polygons, but obviously this is not a practical solution.

(a) Has anyone else seen this and
(b) are there settings in SketchUp than can resolve the issue?

Thanks in advance!

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Most likely your STL file contains tiny geometry which can fail to support faces when imported.

When importing STL files, look under the Options Button in the Import Dialog.
There, set the Scale-Units setting to Meters.
After import, use the Tape Measure or the Scale Tool to scale the import to desired size.


Thank you very much! Great tip!

So, it’s been years, this isn’t fixed?

Now that I’m paying an awful lot of money annually for Pro, has this been fixed, in any way?

3D printed objects are usually in the inch and centimeter size scale realm, there has got to be a fix by now?

There is a fix. What version of SketchUp are you using? Please complete your profile with useful information so we can help you.

I am using SketchUp Pro 2021, the latest version, 21.1.279 64-bit.

When I import an STL, such as a bolt or a wingnut, Sketchup will erase tiny geometry, which is what the software did back when it was a Google freeware project.

In this case, I open the same file in MeshMixer, which is very literal about open faces, and the model is watertight.

But if I open the same file in Sketchup, the geometry is erased.

Is there a way to fix this? It’s been a problem with small geometry since the inception of the software.

Yes, see the answer from Geo above.

As @Box wrote…

You might also consider setting the importer to merge coplanar faces which will help to clean up some of the unneeded geometry.

I would just model the thing myself which would avoid time spent cleaning up the .stl and make a much nicer model. I think I spent more time deciding which wing nut to model than I did modeling it. I settled on one with 1/4-20 threads. The image in the background is from the vendor’s site. Dimensions are based on their supplied CAD file but all of the geometry was created in SketchUp.


no, it wasn’t freeware

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I don’t recall there being a paid version when Google initially released SketchUp after acquiring it from @Last Software in 2006 - I was sure it was only available as a free download initially. It was only later that there was a pro version, yes? The definition of freeware is software that is free to download. So any time there is a free version of a software it is appropriate to refer to it as “freeware.”

While useful advice, what I am hearing is that the underlying problem has not been fixed in 20 years?
The software cannot handle small geometries. Work arounds for a problem are not the same as the problem being fixed: Modelling at 1000x size, not using plug-ins such as cleanup3 without first scaling up models, and modelling things fresh or importing them at huge sizes rather than using models as-is mean there is an underlying problem in the software. Even if I import using a trick, I still can’t work in the actual units. Plug-ins and tools will fail, such as the arc tool refusing to make an arc that is below a certain size.

I do recall, having used SketchUp since version 3. There has always existed a payed SketchUp Pro version that allows commercial use.

Not really. Almost any software is free to download today. Using it is another matter. Freeware is software that is free to download and use, in any way you will.


Sounds like you won’t be satisfied with any solutions offered regarding doing the modeling in SketchUp. Maybe you should be looking at some other application for modeling your small objects.


The software is designed to model buildings and has an internal tolerance of 1 thousandth of an inch.

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It can’t be that hard to build a hack that automatically does where all the people that use this software for modeling for 3D printing do. They model in millimeters, and they set it to meters.

I went to the SketchUp warehouse and searched for a blank box, to see what came up as recently created. A key ring, an audio capacitator, a PVC flange, a euro bill, a table set with detailed flowers and cutlery, all came up along with the buildings and low poly life-sized truck models.

People are using this software to do thing other than model buildings. SketchIp is arguably the fastest rapid drawing tool for 3D modeling. It wouldn’t take much to make the 1000X hack into an actual feature, like a “small objects” template.

If you are a programmer, why not give it a try?

Per a request by Jon Weaver, I “hacked” out a menu command that a shortcut key combo can be assigned to.

He requested a 100x scaling, but it should be easily modified for 1000x.