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Top and Bottom Walls Not Expected
 
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Top and Bottom Walls Not Expected  

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Dennis
 Dennis
(@dennis-3)
Active Member
Top and Bottom Walls Not Expected

I've purchased my first 3D printer (Prusa I3-MK3) and am chomping at the bit waiting for delivery. I'm not sitting idle and am trying to educate myself on the jargon, tools and limitations to this new (to me) media. I've downloaded all the software and have spent some time starting to CAD up some things I want to print. I use SketchUp in case that is relevant to my problem.

  • In the first attached image, you'll see my model as displayed in the 3D section of Slic3r Prusa Edition. It is a thick walled structure, with inner and outer surfaces with outward normals that I think are set correctly. I noted in my early trials if an outward normal is backwards, all hell breaks loose on this screen. You will note that you can see all the way through the model to the bottom plane.

  • The second image shows a slice near the bottom where it is nicely filling up the thick wall area as I expected. However, you can also see that it has some layers on the bottom plane. I'm not sure, but I think it is only one layer.

  • And again, in the third image at the top slice, I again have a layer where I don't expect one. Again, I think it is only one layer.

    • The settings in Slic3r are basically the default ones when started. Some things that I've tried...

  • I first assumed that the Horizontal shells settings would only apply to the bottom and top when there is a wall explicitly there in the model. Then, I thought it was a default setting to apply no matter what. So, I tried them with both set to zero. That made them pretty much go away, but now it has a mesh based on the fill material. (See the fourth image)

  • I unchecked the Ensure vertical shell thickness option since many posts says this causes trouble. It didn't change anything.

    • Now, I don't know what my problem is... CAD software, surface normals, stl output, or bad settings in Slic3r.

    Thanks for any ideas.

    Posted : 09/05/2018 6:57 pm
    Dennis
     Dennis
    (@dennis-3)
    Active Member
    Topic starter answered:
    Devil's in the Details...

    Thought I'd reply to my own. Maybe it'll be of use to someone else of how small of an issue can manifest as something so large. After many hours of Internet learning the issues of "Reversed Edges", "Reversed Faces" and much searching in my SketchUp model, I found the issue. I had accidentally deleted two tinny triangular facets in the model. The two circled regions should be yellow to be a continuation of the shell.

    Posted : 10/05/2018 12:17 am
    matthew.m34
     matthew.m34
    (@matthew-m34)
    Eminent Member
    Re: Top and Bottom Walls Not Expected

    I've had similar issues with stls from some of my models or 3dhubs customers. You can use a STL repair program like Netfabb to fix them using automatic repair. Fixed a gear I made easy. Usually, it's caused by flipped polygons.

    Posted : 12/05/2018 12:27 am
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