Problems exporting model for 3d printing

Hi there!

I created a piece of jewelery which is supposed to be 3D printed. However, every time I export it from Blender 2.8, I end up having some sort of artifacts on the model which are seen in all exported formats to different extent when loading it into MeshUp or to the 3D printer website preview.

This is the view I get in Blender in both, Edit and Object mode:
Image 1

This is the view in MeshUp after export:
Image 3

Somehow it seems to connect vertices upon export which should not be connected and then creates some kind of Z-level difference for a reason I do not know.
The model contains a 3D scanned footprint of a dog which was imprinted into the surface by Boolean->Difference if this information is of any help.

Any suggestions on how to fix this issue are highly appreciated.

Thank you in advance and best regards

P.S. there is a restriction for new users regarding the amount of images and links I can post here in my first post, so unforutnately I am not able to show all images at once…

For completeness please find the other two images:

Belongs to Blender view:
Image 2

Belongs to MeshUp View
Image 4

Check this one - maybe changing export format can help: Preparing a mesh for 3d printing

Thanks, I had a look at the topic you linked but changing to batch mode for export did not help as well as changing other export parameters for the file types I tested (ply, stl, obj, x3d). Anyone else around with an idea what I could do to prevent those atrifacts from appearing?

It’s super hard to tell without actually seeing the file.

My guess is it’s something that happens due to the massive ngons that are created after the boolean. Every application deals with ngons in their own way, especially when you’re dealing with ngons that have super curved edges with extreme number of verts.

I would try two things.

  1. This is faster. Select everything, Triangulate Faces (CTRL+T; EditMode>Face>Triangulate Faces)

2a. This will take more time. Before doing the booleans, make sure your mesh has more then just that one polygon. Make some 20-ish edges grid on it.

2b. A bit faster. just use the knife tool to create those cuts, on the model you already have.

Among Blender default addons, there’s the 3D printing addon, which is useful for detecting artifacts in your objects. Have a try at it.

@ 0rAngE: Triangulate Faces did not result in any change on the model or the exported result unfortunately.

I will try to add a grid before merging although I already put a lot of time in smoothing the edges and scraping the overhangs :frowning:

@kabu: I tried it and when I choose “make Mainfold” it deletes nearly all of my object. I guess its because of the footprint…

I could provide the blender file if this is of any help, it is not that big (about 32 MB)

Thanks for all your suggestions so far! :+1:

P.S.: Closeup of the artifacts:

Your screenshot angles are not helpful. Put proper angles, close ups, wireframe views and shaded wireframe views.

Blender does not merge vertices during exports. Check your object, material, vertex groups to see if some separation happens during export, some formats might by default split object based on those properties.

Also boolean operation is not suitable for cutting up complex holes and merging. If you need such operations you might want to take a look at remeshing in the upcoming 2.81 branch.

Actually one of the easiest ways of making sure a model is going to be print friendly, is runing the voxel remesher on it.

This is a new feature, only in 2.81 builds. Grab the latest 2.81 here:

Select the object, or if you have multiple objects, select them all and Join them.
Then run the Voxel Remesher

I tried the Voxel Remesh and it results in a strongly simplyfied model. Interestingly this one shows the artifacts. It is the first time i get them displayed in blender itself.
Unfortunately I am a bit running out of time as this is meant to be a birthday present which happens to be beginning of november.

I uploaded the file if this might be of any help:
.blend File
.blend1 file

In the meantime I will try suggestion 2b and try to add some verteces to the surface.

Thank you again :slight_smile:

This would be the proper way to ask for help. Your initial posts were screenshots were not sufficient.

The reason why you were getting those “streaks” was because your surface was not flat!
So i selected all those faces and scaled them down Z = 0

The I ran the voxel remesher set to 0.02 (I think)
After that you can optionally apply a Decimate Modifier

I’m uploading the files, it’s gonna take a while. I’ll come back post the links once they’re uploaded.

In the meantime … this is illegal geometry when it comes to printing!!

Decimated

The VoxelRemeshed (wo Decimate) This is a 3.6 Mil mesh! It’s gonna take another ~20 minutes to upload. Wait 30 min before you download!

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Thanks a lot for your help, now the export works perfectly.
Can you tell me which faces were the ones that were not flat? I think i spent i don’t know how long to set all the verteces at the edge of the paw to the Z level of the vertex in the lower corner of one of the edges.

But really thanks a lot for the time you spent helping me!

These are the faces I selected and scaled to Z=0

Mind you, you still would not be able to print this! You still have illegal geometry, that torus ring.
So you’d still need to run the VoxelRemesh on it!
… or do it by many other means where you would get a clean mesh for printing :wink:

Dear 0rAngE,

as you kindly helped me so much, I thought you might be interested in the outcome of the printing process which to my opinion was absolutely successful - mostly thanks to your great help - thanks again! :slight_smile:


Best regards,
Thomas