3D slicer not representing full a hollow 3D SketchUp design

Hello Sketchup Community!
I am new to 3D modelling and 3D printing.
I tried to model a dust port for my tablesaw in SketchUp free.
Then import the STL in Cura.
Cura displays the STL as in Sketchup but does slice it as a full body instead of hollow cylinders.
By any chance, does someone know if I need to do something in SketchUp to make it hollow?
Thanks for your help,

Most likely your model is not a solid in SketchUp. Share the .skp file so we can see what you’ve got and give you guidance for fixing it.

Hello DaveR,

Thanks a lot for your help! This is my very first model ever…


TableSaw_DustPorts_v2.skp (262.3 KB)

The first issue I see when opening the file is the reversed faces shown in blue. The face orientation tells the slicer which side of the face gets the material and which side is air.

If you look at a section cut, you can see a series of vertical edge segments which shouldn’t be there.

Reverse the incorrectly oriented faces and erase those edges inside and you should be in good shape.

By the way, when you drag out the radius for circles, you should make sure to drag out on axis and not just in some random direction as you have in this model.

Thank you DaveR!
I will try to adjust the model.
I might repost the udpated skp for your review if that’s ok!

1 Like

Here I’ve fixed your model and redrew it fresh with the circles dragged out on axis and with more segments so you’ll get a rounder print. The walls seem a bit thin to me but I just used your dimensions.
TableSaw_DustPorts_fixed2.skp (429.7 KB)


It took me more than 2 painful (entertaining) hours to draw my 1st model!
What Black Magic are you using to do it in few minutes!
Thanks a lot for sharing your expertise!
Have a great weekend!

Black magic, ha! Just the basic tools but I’ve been using SketchUp for a few days more than you have. You will catch up soon enough.

I took my son to get some food. When we get back I’ll do something to show you how I did it.

So with no intent to shorten the number of painful entertaining hours you invest in model things like this, here are the basic steps I used.

First draw the square for the base. Round over the corners and add the holes that go all the way through. At this stage you are only modeling details that would be seen on the bottom face.
Screenshot - 3_13_2020 , 6_11_02 PM

Extrude the base to thickness.
Screenshot - 3_13_2020 , 6_11_21 PM

Now add the circles for the tube portions to the top face.
Screenshot - 3_13_2020 , 6_11_50 PM

Push/Pull again to extrude the tubes to height. Doing it in this order avoids creating internal geometry and reversed faces that would otherwise be a problem.


Hello DaveR,
Thanks a lot for the details!
I will use them to update my model as I printed a very draft to test the overall fitting.
As you correctly pointed in your initial post: the walls are too thin, so definitely need to make them thicker.
Also, the printer prints slightly undersized (like 108.8 mm rather than 110mm). I need to figure out how to address that. Maybe within Cura by scaling it?
Thanks again for your precious help,
Have a good weekend!

1 Like

That looks pretty good for a draft.

As for thickening the walls, it might be easiest to just figure the new radii for the circles and enter them. If you select a circle and its radius is displayed in Entity Info with a white field, you can just type in the new radius.

If you wanted to, you could make the circles different radii and add a bit of taper.

As for the base, are its dimensions critical? You can resize it. I’d make the holes larger to be a little sloppy if they have to match perfectly with other holes.

Of course this would be a good time to start over and model it fresh with the new dimensions. Good practice. :wink:

1 Like

I am so happy you did that new post, as I was wondering on how to make tapers/cones!
I have plenty other projects in mind that need cones! Thank you so much!
I will keep you posted!

1 Like

Good luck. Share your progress and photos of the finished parts.

Dave R,

On the very first post you did, when you reviewed the first model, you mentioned that when creating circles it is better to do it on a axis. I now see how to do it in Sketchup, but I don’t understand:
a) how did you realise I did that way?
b) I suspect doing circles on axis makes the model more “robust”, but is it really bad not doing it?


In your model it is pretty obvious because the vertices don’t line up. Here I’ve added a couple of guidlines from the center to vertices on the outer edge. Notice that the vertices of the inner circles don’t come close to being on those guidelines. Also notice how the wall thickness varies.

On mine I dragged all the radii out on axis (habit now and hard not to do) so all the vertices line up on the guidelines. I increased the number of sides for the circles to make smoother cylinders since you’ll want want to make a reasonably good seal with the DC hose.

Keeping the radii on axis makes the model easier to work with in general. Especially when you start needing to make modifications or in cases where you might need to divide the circle into smaller segments.

For example, I started out modeling the felloes for this spinning wheel as a single piece using a profile of the wheel and Follow Me. Then I “cut” out one of the felloes with the bridle joint detail at each end and erased the rest. After making the remainder a component.I used Copy/Rotate to make the rest of the wheel.This sort of thing is why it’s a good idea to use a multiple of 12 for the number of sides on circles, too. Divisible by 2,3,4, and 6. (there are cases where you might vary from that if you need to divide by 5 but most of the time the multiple of 12 works best.

With Hidden Geometry turned on you can see that the joints all fall on natural dividing points on the circle.

1 Like

This is brilliant!
Thanks for taking the time educating me on that!

1 Like