Cura is filling in cutouts represented by Sketchup

As you can see, in sketchup the bottom has a cutout, Cura shows correctly before slicing. But when you slice, it makes the circle a solid piece even with all supports and build plate adhesion off. When I flp the model upside down, the same circle get filled.


I don’t see your SketchUp file but this sounds like a Cura problem, not a SketchUp problem. Last week someone was having a similar problem with Cura although their model was fine in other slicer software.

I made a similar model, and in Cura 3.6 the slice prepare doesn’t give you a preview. Then I tried in Cura 4, and you do get a preview. Here’s how my slice preview looks:

Notice that I have no red edges, which I gather is Cura’s way of telling you there is something wrong with your model.

Here’s my what it looks like in sketchup. This is a two part model and both are having similar issue…

The extruded cylinder is inside out. Fix the face orientation. You should only see white front faces.

The top part of the model is inside out. The white faces are front and the blue are back faces.
A simple try to fix it: Select one of the white faces and right click, from the context menu choose “orient faces”. That should orient all the faces front (white) outside…

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Another version I did, with the faces the right way.

FWIW, I’m going to guess that your first few steps looked something like this.

You outlined the taller section on the 2D circle before extruding the flange. This results in the reversed faces and potentially also creates internal faces which will be a problem.

If instead you extrude the flange and then add the outline for the taller part of the cylinder, you don’t end up with any reversed faces or internal faces and there’s less work to do to clean up the model.

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Wow I did not know cura cares about what’s inside and what’s outside. I will try this later when I get back. Thanks for the help

It was an interesting shape to model. I did something on the lines of what you showed, but was careful about which way the faces were.

I just made a new version, that doesn’t leave any visible lines. I’m sure you know what way I did this time!

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Face orientation tells the slicer software which side of the faces is air and which side is the printing material.

How did you get rid of all the lines? This is my first attempt to do something from sketchup for 3d printing.

I’m doing a copy cat pool skimmer of something that’s commercially available.

My design calls for 2 similar shaped cylinder one to be fit inside the other allowing me to turn them to either open or close. I designed with with a 0.5mm gap, is this enough for a tight fit that would allow it to turn freely?

The lines being visible won’t matter to the 3D print. You can get of lines by ctrl-click with the eraser, or right-click/Soften. With my last version I used the follow me tool to make the complete cylinder, then a couple of boxes and the solid tools to to subtract out the gaps. That way there were no lines to have to hide.

The tolerance may depend on the printer and the material you’re using. You could do a small height test print of just the cylinder parts to see if it gets tight.

I drew the circle then devided by 100 to get my clinder. In cura, I can still see the slight line this is a rather large print so I would like to get the details nailed down before drilling down the 15 hour print. It’s going to be two cylinder sliding into each other and be able to turn freely. I wonder if those lines will have an affect on it. I’m printing with an Ender 3 and it’s very well calibrated I just need my model to be as well :slight_smile:

SketchUp seems to have a 999 limit for segments. That looks smooth enough in Cura.

ahh learning sketchup and cura both at once… I did not know about the 999, the youtube videos I’ve been watching said to do 100 or so. I just tested using 99 and it’s perfect. I’m printing the model at at 25% scale @ the moment to test fit. Using thingiverse is quick and easy but once I get this right, I will feel accomplished!

999 is overkill for most things.

It’s good practice to use a number that is a multiple of 12 as that makes it divisible by 2,3, and 4. An exception is when you have to divide the circle into some other number. The hand wheels on this lathe have five spokes so circles are created with multiple of 5 sides.

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996 would work then! For this kind of model I don’t think the 3D printer will mind whether the angle change for each segment is 0.36144578 or 0.36036036.