Looks Good In Sketchup Very bad in .stl file


I am new to both SketchUp and 3d printing. (about 5 weeks now)

This is my first complex part and after working through the several tutorials from Trimble and others on Youtube I was pretty proud of this part! It looks pretty nice in SketchUp but when I get it into the slicer software and print it it’s a different story!

I am willing to bet way down in some pull down sub-menu there is EXACTLY the thing I need to fix this in one click though!

I am going to post several images so you can see what I see…the first two images are in SketchUp (I discovered we have a one image per post rule so several posts follow) …

So what am I doing wrong? Or better yet, what magic tool can I click :slight_smile: (besides smoothing) that will actually take all those “wrinkles” out?


Can a SketchUp model be 3D printed?

Now I did REALLY struggle to get a circle on one end and a rectangle with different radii on the other end AND make it look nice (this is an RC Airplane model part) Now after I got the long period of stretching, shrinking extending, moving, etc to get nice flowing lines I did use he smoothing tool.

and Hey, it looks NICE! I was so happy!


Then I exported it to STL and in the slicing software you see some shading that is not quite, uhhhh, smooth but still not too shabby!


But then when you slice it you can really see it…So how did I screw this up so badly?


Unfotunately, that is probably what your model looks like in SketchUp, too. Only difference is that you have those edges smoothed, right now.

If you can share the file, some folks around here can probably post steps to generate smoother geometry from the get-go, and help create a nice smooth file for printing.


Well duh! to me! I supposed that is much better than screen shots!

So here is how I started. I post this only in case I did it wrong from the git-go .

Note the name, this was my 5th try at doing this cowl :wink:

So this is 5-3 early in the process where I have the firewall and spinner situated – so you can see how I was going–. extrude then stretch out to the guidelines I had drawn.

COWL_5-2.skp (1.2 MB)


This I late in the process I still had a little stretching to do but this is before I smoothed and added color.

COWL_5-5.skp (1.3 MB)


And this is the final version I that the screen shots at top were taken from. This is what the .STL was generated from.

KAV_COWL_chin.skp (1.5 MB)


Other than the wrinkles for my first project I am thrilled to death! Lovely lines!


I would try redoing the geometry. I took it and copied out the top “ring” and 3 “rings’ from the bottom”

The top ring needed a lot of clean up. The goal is to get a single line all the way around. No breaks, and no extra lines. Once that is the case, you can Weld them together using the Weld extension. Then the fun begins! Select the top ring and the second tallest ring and use Fredo’s Curviloft - Loft by Spline to generate new, smooth geometry between the rings!

Do the same process between the rings as you move down the shape:

Once you add the three lofts, you end up with a similar, but much smoother shape:


Holy tamoli! You did that and reposted it in the time it took to me proofread my own posts!

Thank you so much even though now I have some more learning to do! LOL!


Robajohn; Ususally you want the design to be thin walled else the slicer assumes it is total solid and the print requires a lots of filament. Did you have that issue?


Well, early on I saw a thing on a YouTube from a guy named “Master Sketchup” and his advise was to just send it to the slicer as a solid and then in the slicer software convert it to hollow. (LOL “early on”! I have been doing this a whole 5 weeks now!)

If you look at the dialog on the left in the shot below you see “shell thickness” and more importantly “fill density”. As you can see I have fill density" set to 0 and that makes it hollow. Shell thickness sets how thick the walls are. When I actually printed this I did 2 mm walls . (ignore the red arrow as this screen shot is for another question- it just came in handy for your question as well)


If you are getting the thickness needed and not wasting material then
that is what is important, looks like slicers are getting much better now.

Some I looked at couple months back would add what they called infill
and would even add like structure to inside.

Good Luck


To TheOnlyAarron, Thank you so much. I spent the weekend pounding the mouse learning and practicing what you taught me in one short post! My proficiency has increased dramatically. I can do a better drawing in far less time now. Hell, in a few years I might get good at this! :slight_smile:


Happy to help!


Check it out man! You taught me how to do this! I am getting better thanks to all the help from you and others! That one up top that looks so crappy took me about 8 hours to make! This one took me about two hours with far more detail and looking way better to boot!

Again, a big “thank you” to you and all the other coaches on these boards!


It printed while I was at work! I just had to show off my first completed project. Now I will let this thread die a merciful death! ! LOL


Awesome job, @Robajohn!