STL to Solid - "Part object is not a shell" error

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chrisb
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Re: STL to Solid - "Part object is not a shell" error

Post by chrisb »

What's the use of this post besides citing a 4 years old post of Normand?
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bejant
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Re: STL to Solid - "Part object is not a shell" error

Post by bejant »

chrisb wrote: Tue Mar 14, 2017 7:27 am It was funny reading Mark's comment urging to upgrade.
(snip)
I do miss Mark's comments. He helped me a lot with my first FreeCAD steps.
I miss his comments too - sometimes he wrote some pretty humorous stuff. He joined the forum not long after I did, and he helped me a quite a bit along the way as well.
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NormandC
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Re: STL to Solid - "Part object is not a shell" error

Post by NormandC »

chrisb wrote: Fri Aug 17, 2018 9:55 pm What's the use of this post besides citing a 4 years old post of Normand?
If you look closely at Maryfreecad's post, new text was added inside my quote. The following is *not* mine.

Maryfreecad wrote: Mon Aug 13, 2018 2:33 pm I have the same problem. Is there anybody to help please?
As the "IMPORTANT: Please read first before asking for help" announcement at the top states:
Please provide a complete description of your problem
The best way to get quick and efficient help is to not spare any details. What workbench and tools are you using? What steps did you take? What was the result? This will avoid back-and-forth exchanges and save time for everybody.
And please post the STL file you're having problems with, or a link to download it (without registration please).
scottdmills71
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Re: STL to Solid - "Part object is not a shell" error

Post by scottdmills71 »

versions 16,17,18 linux xubuntu 18.04
netfabb 2019 windows 10

thingiverse files
https://www.thingiverse.com/thing:291123
https://www.thingiverse.com/thing:1897860
https://www.thingiverse.com/thing:3555943
https://www.thingiverse.com/thing:2767754

Are there any new techniques to the process? I have tried 3 different versions of the software 16,17,18 and when I cant convert the part to a solid, no techniques i have tried are ever successful. I know I am not giving any specific file that I am having trouble with so here is just 1 that I would like to convert I have downloaded and tried techniques on all Battlestar galactica cylon raiders from thingiverse. Fantastically detailed models, however I want to convert the models to a functional toy within freecad, rather than printing and ripping apart physically. I have mnaged to get meshes out of almost all of them, but cannot convert to solid. I have ran them all through netfabb 2019 and repaired , took them back to freecad 16,17,18 and still cannot convert to solid. Is there anyway that I can just take the converted mesh find the holes and manually close them ? I can do it by using advanced utilities to create shapes however that is painstakingly slow when there are thousands and thousands of faces. Isn't there a better recipe to follow for converting something I download on thingiverse into something new from a STL file.
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quick61
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Re: STL to Solid - "Part object is not a shell" error

Post by quick61 »

scottdmills71 wrote: Mon May 27, 2019 1:39 am versions 16,17,18 linux xubuntu 18.04
netfabb 2019 windows 10

thingiverse files
https://www.thingiverse.com/thing:291123
https://www.thingiverse.com/thing:1897860
https://www.thingiverse.com/thing:3555943
https://www.thingiverse.com/thing:2767754

Are there any new techniques to the process? I have tried 3 different versions of the software 16,17,18 and when I cant convert the part to a solid, no techniques i have tried are ever successful. I know I am not giving any specific file that I am having trouble with so here is just 1 that I would like to convert I have downloaded and tried techniques on all Battlestar galactica cylon raiders from thingiverse. Fantastically detailed models, however I want to convert the models to a functional toy within freecad, rather than printing and ripping apart physically. I have mnaged to get meshes out of almost all of them, but cannot convert to solid. I have ran them all through netfabb 2019 and repaired , took them back to freecad 16,17,18 and still cannot convert to solid. Is there anyway that I can just take the converted mesh find the holes and manually close them ? I can do it by using advanced utilities to create shapes however that is painstakingly slow when there are thousands and thousands of faces. Isn't there a better recipe to follow for converting something I download on thingiverse into something new from a STL file.
Not really. To this day, the STL format remains, for all practical purposes, a one way trip. Sure, one can convert between the two with simpler objects, like a cube, but anything with a curved surface, even when it converts to a solid, its still a bunch of flat triangles on the surface. The more triangles there are, the harder it is to work with.

I looked at one of the models you linked to and it is full of self intersecting faces, like a gaggle of them. This will never convert successfully to a solid. Even if you do get a "solid" out of it, it will be so full of selfintersect errors one would not be able to perform any further operation with it. One would be better off to do whatever needs to be done in a program like Blender. Much more useful for working with meshes.

Not really understanding what you mean by "a functional toy within freecad", but anything you might want to do with a meshed object in FreeCAD, converted or not, you can do better in a mesh modeler like Blender. The right tool for the job kind of thing. This coming from someone that has his workbench littered with at least a few custom angled screwdrivers as a result from various attempts to have them emulate a crowbar. :shock:

I can relate to what you are going through at the moment, as I was right there with you when I was first starting out with FreeCAD, and to be honest, it took a country minuet, (much longer than a New Your minuet by any measure), to come to the realization of what I have said above. Yea, it's learning another modeler program. The upside to learning a program like Blender is that it can be a wonderful companion in your modeling tool chest for providing a great way to render your models to photo realistic quality, as well as being the right tool for the job when working with and modifying meshed objects.

Mark
This post made with 0.0% Micro$oft products - GOT LINUX?
gzegers
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Re: STL to Solid - "Part object is not a shell" error

Post by gzegers »

NormandC wrote: Mon May 19, 2014 4:41 pm Then it probably means that the mesh does not form a valid enclosed volume (shell).

Switch to the Mesh design workbench, select the mesh object then go to the menu Meshes --> Analyze --> Check solid mesh.

What does it tell you?

Also, can you attach the mesh so we can have a look at it?
Hi,

I have the same problem. I follow these steps: To convert a mesh object to a solid, here are the steps:
Switch to the Part workbench
Select the mesh, and go to the Part menu --> Create shape from mesh
Click OK to the dialog
Select the newly created shape
Go to Part --> Convert to solid

and get "Part object is not a shell" error.

When I analize the mesh I get "The mesh is a solid"

Anyone can help?

Here is the link to the .stl file. I want to convert it to a solid to make a boolean operation between this geometry and a rectangle

https://uofc-my.sharepoint.com/:u:/g/pe ... A?e=R9OzSK

Thanks!

Gerardo
chrisb
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Re: STL to Solid - "Part object is not a shell" error

Post by chrisb »

Hi and welcome to the forum!

The shape cannot be converted to a solid, because the pieces are unconnected. Before creating the shape you should split the mesh in
MeshDesign workbench with "Split by components".

There seem to be repeated shapes, perhaps you can take advantage of that by using clones.
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jeno
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Re: STL to Solid - "Part object is not a shell" error

Post by jeno »

gzegers wrote: Sat Mar 06, 2021 12:20 am
Hi,

I have the same problem. I follow these steps: To convert a mesh object to a solid, here are the steps:
Switch to the Part workbench
Select the mesh, and go to the Part menu --> Create shape from mesh
Click OK to the dialog
Select the newly created shape
Go to Part --> Convert to solid

and get "Part object is not a shell" error.
When I analize the mesh I get "The mesh is a solid"
Anyone can help?

Here is the link to the .stl file. I want to convert it to a solid to make a boolean operation between this geometry and a rectangle

Thanks!

Gerardo
Hi Gerardo,
I think this is what you are after
blocky.png
blocky.png (57.74 KiB) Viewed 3441 times
From my point of view this is not a job for a CAD

Regards
Attachments
cube-blocky.zip
(890.48 KiB) Downloaded 50 times
ragdollfun
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Re: STL to Solid - "Part object is not a shell" error

Post by ragdollfun »

Hello everyone,

My first post on this forum, forgive me if I'm not clear enough in my explanations, not only is english not my first language, I am new to FreeCAD and to CAD/CAE in general.

I've been struggling for a few days now to turn a STL file obtained from a 3D scan into a "part" usable in FreeCAD. I've tried the instructions below originally posted by NormandC without success:
NormandC wrote: Mon May 19, 2014 3:31 am Hello,

To convert a mesh object to a solid, here are the steps:
  1. Switch to the Part workbench
  2. Select the mesh, and go to the Part menu --> Create shape from mesh
  3. Click OK to the dialog
  4. Select the newly created shape
  5. Go to Part --> Convert to solid
  6. Select the newly created solid
  7. Go to Part --> Refine shape
The last step is not necessary, but it will clean the solid of most of its residual edges on planar and cylindrical surfaces.
After reading through the different answers in this thread, it was finally chrisb's answer which helped me solve the issue:
chrisb wrote: Sat Mar 06, 2021 12:42 am Hi and welcome to the forum!

The shape cannot be converted to a solid, because the pieces are unconnected. Before creating the shape you should split the mesh in
MeshDesign workbench with "Split by components".

There seem to be repeated shapes, perhaps you can take advantage of that by using clones.
So here is my recipe which builds upon the different answers one can find in this thread:
  1. Import your STL file into your project.
  2. Select "Mesh Design" workbench.
  3. There are 2 crucial requirements that your mesh needs to satisfy if you want to be able to turn it into a "Solid":
    • First, you need to make sure that your mesh is entirely connected. In order to do so, you can use the "Split selected mesh into its components" tool in order to separate the parts of your mesh which are not connected into different "components". Now you simply select the component that forms the actual object that you want to turn into a "Solid" (and optionally you can delete the "parasite" components that you do not need).
    • Next, your selected component (or the original mesh if it was already made out of a single component) needs to pass the "Checks whether the mesh is a solid" test/tool, which checks that your mesh forms a closed form, meaning that there are no holes. At this point, if your mesh/component does not pass the test, I used the "Close holes interactively" tool in order to close any holes that might appear in the structure (clicking on the border/edge of holes seems to do the trick for me).
  4. Once you have a single fully connected mesh that passes the solid test, switch to the "Part" workbench. Finally you can follow NormandC's steps to the letter:
  5. Select the mesh, and go to the Part menu --> Create shape from mesh
  6. Click OK to the dialog
  7. Select the newly created shape
  8. Go to Part --> Convert to solid
I hope this post will be helpful to anyone coming to this forum looking for a full answer.
Bladevane
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Re: STL to Solid - "Part object is not a shell" error

Post by Bladevane »

@ragdollfun - I just came across this thread as I was having a very similar problem. Thank you for the explanation. And by the way, your English is as good as it needs to be.
Last edited by Bladevane on Tue Jul 12, 2022 7:07 pm, edited 1 time in total.
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