Manifold Blender > OBJ/STL > Meshmixer = Not Manifold?

[Anonymous]

I have this model, a Blender file, and I want to 3Dprint it for my kid.  (A DH88, like Bulldog in the the Planes movie if your curious).  Anyway, I can get Blender to export it to an OBJ or STL, and I can open the OBJ or STL in Cura and slice it without issue, except I would rather make a few changes and break it into pieces so I can print it bigger.

Importing into Fusion 360 was... interesting.  Apparently, the wrong tool for the job.  I like Fusion 360, so, I thought I'd try Meshmixer.  Got my head wrapped around it, got it to do a cut, but when I went to separate shells... oh boy.  That didn't work.  So, I learned about Analysis and Inspector... Ha!  300 odd pink balls with lines, bunch of blue ones, some red as well.  I get the same results via OBJ or STL import.  Manifold, it 'aint.

So... what am I doing wrong?

I expect Blender is a wonderful and powerful program, but the interface... Meshmixer seems a lot more in line with how I think.  I don't mind learning, but given a choice it would be Meshmixer over Blender.  Just me... not saying that's the right choice for everyone.  I suppose I could go through and fix every one of those pink spheres... probably learn a lot about Meshmixer by the time I'm done.  But, I expect my kid will have moved on to some other thing by then... like College.  If there's some easy Blender to Meshmixer trick that keeps the manifold universe intact, I'd appreciate knowing it.

David...

[Anonymous · Accepted solution]

Pink markers in Inspector point to tiny non connected shells. This is meant for outliers removal (e.g. if you process a scanning result).

In case of a modelled object (recommended exchange format is .obj) you might want to keep all those details. So there's a SmallThresh slider in Inspector which sets the size of what is treated as "small". Pull it down. If the markers disappear: Anything is fine. If they turn to blue or red the tiny pieces own defects (open boundaries = blue, non manifold issues = red) this needs some repair...

Instead of fixing all issues and to construct a single shell object from a bundle of shells for printing in one go, try EDIT/MakeSolid which uses vocalisation to weld shells. MakeSolid starts with a default vocalisation setting. This default result might not be fine enough to embed the details properly. So set a higher SolidAccuracy and MeshDensity (and if there a sharp edges on your source set SolidType to SharpEdgePreserve - which is slower) and hit Update. Voxelisation is easy but costly in file size.

[Anonymous]

Auto correction error: read "voxelisation" instead of "vocalisation" 😉

[Anonymous]

thank you... The inspector adjustments mostly turned the pink to red/blue.  Lots of issues.

I'm waiting for the convert to solid now.  I had tried that earlier, and just had the model turn into something that looked like a 3 year old sculpted out of playdough 😉  On the other hand, the settings you mentioned were bringing back more and more detail... I've hopes for something good once it stops thinking about it.

Since posting, I've also learned that while it will import and slice in Cura just fine... the results are not fine.  Many details simply didn't show up in the layers view, even though they're visible in solid view.

(that converting to solid with preserve sharp edges is sure taking its time)

So, I decided to have at it in Meshmixer, editing the file (well, attempting to do so... lots to learn) and in the process discovered that many parts of the model, while "manifold" are actually hollow... and there's stuff inside.  Gauges and the like. 

So, it's not just an import issue.  The model is not as printable as I had thought.

Well, it finished its convert... mostly there, but significant chunks are still missing, even with all the settings you mentioned cranked way up.  So, I think I'm going to have at a few areas that didn't covert to solid and see if I can make those Analysis issues go away.   Seems, I can convert to solid to see where I need to focus on at least.

Well, might try one more shot on the conversion at max and see what happens.

Thanks for quick reply and useful information.  

David...

[Anonymous]

Just a note at the slider:

If 512 (sliders max here) isn't enough you can even set higher values by editing the displayed values (double click them) or by dragging the sliders over their limits while moving the mouse slightly upwards.

To find proper settings for the sliders try them in SolidType = Fast first. When you're fine with the details (ignoring sharp edges) switch to SharpEdgePreserve finally.

[Anonymous]

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@Anonymous wrote:

Just a note at the slider:

If 512 (sliders max here) isn't enough you can even set higher values by editing the displayed values (double click them) or by dragging the sliders over their limits while moving the mouse slightly upwards.

To find proper settings for the sliders try them in SolidType = Fast first. When you're fine with the details (ignoring sharp edges) switch to SharpEdgePreserve finally.

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Ha!  Now, I never would have tried editing the numbers directly... that's downright sneaky.  And, yeah, still a lot of missing details at the 512/512 and preserve. I'll have another go later...

Thanks again,

David...