Can Smoothing be Turned Off?


When I import a STL file into sketchup, it starts off fine…a bunch of triangles and faces. Then I start to work it and smoothing takes place.

I don’t want it smoothed…it is harder to work it.

Can I turn off smoothing somewhere?

I have tried to select the model, the bring up the smooth dialog box, but unchecking the boxes does not seem to help.

Can I do something in Styles?

What activates Smoothing?


I don’t know why it would automatically smooth if the edges weren’t smoothed to begin with. You can unsmooth by selecting all of the geometry and then running the Soften/Smooth slider all the way to the left. Alternatively, you could just turn on Hidden Geometry


Triple-click your model, whiich selects all contiguous geometry. Right-click > Soften/Smooth. On the Soften/Smooth dialog, move the slider all the way to the left. You can also make softened edges visible individually with Ctrl+Shift+Eraser.


Curses! DaveR!


Thanks Dave…Turning On Hidden Geometry worked perfectly. And I got a response in under a minute…wow.


Be patient, sometimes it takes a while. :wink:


I’m guessing you are using Windows, and a SketchUp version older than SU2016? Am I correct?
There was a bug in older versions where Soft+Smooth could inadvertently be triggered under Windows versions of SketchUp.


Yes, correct on both…Windows and 2015. Are you saying that 2016 will correct this bug?

On a broader level, I don’t understand why smooth can not be turned off altogether. It makes it much harder to work directly on a large mesh.

Ultimately I’m trying to remove undercuts so I can grind out the shape using my homemade CNC machine.

Is there a better way to remove undercuts from a mesh. Someone suggested a blanketing tool in rhino, so I have been looking for something similar in sketchup extensions?

Thanks Tom…

Any suggestions?


What does the mesh look like?


Good question…it is one side of a Rhino’s head. Here is an image of it with a smooth surface:

Here it is with when I choose to View > Hidden Geometry:

Notice the ear does not show up in the first one because it is hidden. I cut it away from the rest of the head to CNC separately.

I’m not sure how well you can see this but the nostril and the eye have undercuts.

I need to remove these undercuts.


There are a few ways to approach your undercuts.

If the head is actually made of 2 parts, you can use the Smoove tool from the Sandbox extension. Usually Smoove does its thing along the blue axis. But Smoove + Shift lets the tool work perpendicular to a surface. Take a look at this Kitty. In that case, the Smoove tool works on a 3D shape because the cat is low-poly and the Smooving radius is set fairly small. The Smoove tool does not just work on the surface you place the tool on, it will also move any surfaces behind the surface you are adjusting. So the Smoove tool cannot just be use on the rhino undercuts if the rhino is one piece. But give it a try and see if it can work. And the Artisan plugin I linked to in the Kitty example should have a tool that would work.

You also could replace the eye and nostril with new geometry. Cut out the eye and nostril. Position a spheroid model in place and intersect the parts.

You could also Push/Pull new eye socket and nostrils. First you need to delete the undercutting geometry. It needs to be a clean cut so a flat face is formed. Position a circle or rectangular face where it would make a nice cutting plane. Select the cutting plane and rhino > r-click > Intersect. Delete the old undercutting geometry and unneeded outer edge of the cutting plane. Then you can use Push/Pull and the Scale tool to make new sockets. The method is similar to shaping this kidney bean
except you don’t have any Arc cardinal points to adjust the outer perimeter. Though if you want, it would be possible to add cardinal points if you get creative :wink:


Thanks cat… you explained that quit well and in depth. I ended up using two of your approaches. The nostril was very deep so I used the intersect a plain with model approach. It was tricky because I had to keep trimming the plain so it did not cut into other areas of the skin.

The eye just needed a little push pull so I used the smooth tool in sandbox.

Your website is a great find…I’ll be exploring it at length in the coming weeks. Thanks for all your work.



I’m not sure what you mean by this? You want to unsmooth a mesh that has smooth/soft edges?


Quite often for doing sculpture, one needs to see all the edges to model. The OP did not know about HIdden Edges - which makes all edges visible enough to tweak away.


Thanks to this forum I am making progress. If anyone is interested. I have been building web pages about this project. The site also explains how to use the CNC machine I built. I’m using the Rhino Project to explain the process. You can find it here: