Gaps in exported .stl file

modeling

#1

I’m making a dome for a model building. The .skp looks like this. It is made up of 18 overlapping taper extrusions.
The slicer makes gaps between the extrusions like this
The 3d printed result looks like this

Apologies in advance if this has been resolved elsewhere - I have searched the forum assiduously but in vain.


#2

How about sharing the SKP file so we can see what you’ve got?


#3

I can’t even see any images in your post.

But taking a blind guess, I wonder if your model detail is just too small? Search forum for the ‘Dave method’ of working on a scaled up copy of your component model.


#4

The slicer software for your printer?
Without seeing the model I’m going to guess that you have some faces reversed. Each face have a front and back side - for 3D printing you need to ensure that all faces have the front side facing outwards. From the Styles panel you can assign colors to the default front and backside. I typically set the backside to a bright red or something, so it’s clearly visible.

You can also install my Solid Inspector² extension: https://extensions.sketchup.com/en/content/solid-inspector²


#5

dome 06.skp (2.0 MB)
Thanks for your reply. This is the .skp file
dome layer 36 cura
This the Cura slice - v.15.06.02


and the finished result.
Sorry I didn’t upload the images correctly before - I’m new to this
Andy


#6

Many thanks for your response.
I use Cura to show the slice profiles as the slicer I use for printing doesn’t do this (customised MultiMaker)
I have run your Solid Inspector and corrected 3 faces, but to no avail. Thanks for the tip about the styles panel. Andy


#7

Well its definitely not solid, which is probably the cause of your problem, this is a tough one!

What is all the internal stuff? , Do you want voids inside or just a solid shell?


#8

Many thanks for replying.
I did wonder if it was too small. I did try scaling up to draw and then rescaling to the required size, but it didn’t work then. I may not have tried hard enough. I have to go to work now but I’ll try again later
Andy


#9

Ian beat me to it. I see the same as he shows. It’s no wonder you have problems with it.


#10

Thanks v much for that. The internal stuff is from the overlapping taper extrusions I used to make the crenations. I’ll upload one extrusion when I get back from work.
Andy


#11

The small size is also a problem.


#12

dome 06Ian.skp (2.1 MB)

Good golly, heres what I have so far. All the components are solid, I think it could be better but its 2am and my patience is run for now! If anyone wants to take it up your welcome to do so.

I made the top a solid component and then made a solid tube component first
The alignment seemed off centre with the top piece (the original is the left upper centre)

I then squared a tube component back centrally on the axis like so (The diameter is the same as original)

I copy rotated the tube and made into alternating 1 and 2 unique tubes with the hope of trimming one against the other to tidy it up. That didn’t work as I hoped, I also tried outer shell but my laptop hates that operation and I gave up on that one!

Its very messy still and could do with more work, but solid and would probably print ok


#13

Many thanks again. I think I follow what you did. However when sliced it still looks like this

so the dreaded gaps are still there.
I have thought that the gap is where faces (from adjacent extrusions) intersect, but for some reason apparently do not generate a boundary where they do.
Also, my method generates a great many redundant lines (the messy interior) and I wonder if I have thereby abused Sketchup’s hospitality. Maybe there is a better way of doing it? Crenated domes are common in architecture I believe.
I’ll try the Dave Method again.
Thanks again for your support. It is much appreciated.
Andy


#14

Repeated the Dave method - drew x100 then scaled .01. Same result.
As for the complexity issue, a test array of cylinders got the same result on slicing, even the though the Cura solid view looked solid.cylinder circular array.skp (152.6 KB)
The gaps are still with us.

This should not happen surely? Can anyone advise where to go next?


#15

Have you tried combining all the separate objects into a single one?

Your test model shows the cylinders overlap in the same pattern of your holes seen in your screenshot. To me it looks like you get a boolean effect out of that.

With your latest attached model you have intersecting objects that will cause internal faces when exporting to STL.

I think you should have better results if the object you send to your printer is a single manifold instance in SketchUp.


#16

I’ll try anything. I have tried making the whole model a component - same result.
How can I ensure that the object is a single manifold instance.
By the way I repeated the cylinder array, but by making an array of circles and deleting the internal boundary lines before extrusion. No gaps!
Cylinder array


#17

You may be making life hard for yourself, what is the actual shape you are wanting to produce?

Is it something like this?
Dome


#18

You want to merge the groups/instances in SU into a single one. If all the separate instances are solids you can use SketchUp’s Solid tools (there is a whole toolbar) if you have the pro version.

If you don’t have pro then you can try to explode all the instance and intersect them with each other. Then remove the internal faces (Solid Inspector might be able to get rid of those.)


#19

Very close (I might want to fiddle with the cap - the rest of it is beautiful).
May I humbly ask how you did this?


#20

Do you have Fredo’s plugin, Curviloft?