Working with STL files?

[nraynaud]

Hi all, 

I am trying to work with a simple STL file, but I can't find a usable workflow.

The part is a simple Settlers of Catan road form thingiverse ( http://www.thingiverse.com/thing:1238980 ) :

I need a ton of that parts, so I want to shell it (the bottom is flat), draft it and maybe even subtract it to create a negative mold.

I imported the STL file, and simply converted it to a BREP, but it kept all the triangles as surfaces even the coplanar ones, I tried fiddling with face groups before conversion, but it looks like they are not used for that (or I didn't discover the workflow).

I tried to directly convert it in the sculpting studio, but the conversion was rejected because of the model complexity.

I tried to pull a high vertex count plane towards the mesh in the sculpting environment too, but it take dozens of minutes to do any operation, and I couldn't get any good result.

Does anyone have a good idea of how to recover this shape in a usable form in the model environment?

Thanks for your help

[TrippyLighting]

I hope this does not come across as arrogant or lazy, however an number of "us" have explained in great length detail what the available option are to work with triangulated mess...sorry...mesh files. If you search the forum for the term "stl file" you'll have several days worth of reading that cover all possible aspects of this.

In general .stl files are the least comon denominator to convey a 3D shape. They contain a triagulated mesh  with a finite resolution and in order to retain details they are usually very dense.

If you want to convert this into someting more editable that also retains all the detaills you'll have to convert this high density triangle mesh into a quad-mesh, that then can be converted into a T-Spline. You could start with InstantMeshes  and see if that will create  a mesh good enough for import and conversion into a T-SPline.

[MichaelAubry]

Cool project.  Totally do-able. Curtis Chan did a project that is similar: 

For this particular shape I think you can have great success by deleting the bottom and side walls (which can be done in the Fusion mesh preview environment in Fusion or any other stl manipulation software like Meshmixer) and replace with natively fusion created solid geometry (like a block w/ a draft) and Combine the results.

The blending of the solid and mesh will require some tinkering using Combine. Key is make sure there's a closed volume for it to combine into.  I discuss how to do this to make a mold in this video (fast forward to around minute 20:00) which should give you some ideas.  

Good luck and have fun!

Mike

[nraynaud]

I have spent some time googling for smart ways to handle STL files, interesting answers might be there, but they are lost in lazy tutorials and "my mesh is sideways" questions.

Generally I give the people who work with me a rule when dealing with others: you can only answer "RTFM" to someone if you give them the exact link to the answer in said manual at the same time, never assume they have found a detail in a ocean of data or crappy manuals while they were in a rush or often interrupted.

I understand your point about STL files, but after looking, I can't find the original CAD files. I did that before even googling how to import STL files and again before coming to ask here, knowing that it would probably not be a pleasant experience.

[nraynaud]

Thanks, I'll chew on that, I had not seen those video it looks like I need to get 2 more apps, tho. I hope they are free.

[MichaelAubry]

Awesome!

You don't have to buy anything extra. Mesh preview is already in Fusion. Just turn it on: http://www.autodesk.com/products/fusion-360/blog/july-27-2016-update-whats-new/

Or download Meshmixer here: http://www.meshmixer.com/

Have fun.

[nraynaud]

Thanks for your help,

I spent a bit of time with all that, I can't find a smart workflow.

Meshmixer can reduce the triangle count, but it's not really useful because fusion 360 can remesh too

Remake just never finishes saving the quad .obj file (it's just hogging the CPU until I kill it)

Instant Meshes doesn't give a result suitable for import as a sculpture thingie, either I reduce the triangle count and it doesn't follow the shape, or I increase the triangle count and it would be stupid to try to import it in the spline system. I'm a bit skeptical of this idea in general, because I also need the crease information to reproduce the shape.

I could get fusion 360 to convert the mesh to a solid, but it fails to shell it.

I went with the mesh direct conversion to b-rep, sliced the bottom to shell it and stuck the top of the road back on it, but everything is very slow, and I many operations fail.

I guess it's the last time I try to use STL files with fusion 360, it's really frustrating.

Thanks again for having tried to help.

Nicolas.

[TrippyLighting]

I've been successful in  converting this Mesh into a quad mesh with InstantMeshes and Blender, but in both cases Fusion 360 reports errors that Autorepair is not able to repair.

Again, I find Fusion 360's error messages unintelligible. I'll keep working on this though!

[TrippyLighting]

Also, if you need really close reproduction none of these semiautomatic remeshing tools will do that very well for exactly the reasons you describe. You either have to deal with some loss of detail, or you retain the detail but then end up with high polygon counts so the T-Spline becomes un-editable.

You would need to look into re-topologizing tools such as Topogun,which is a standalone software or Retopoflow, which is a plugin for Blender. But they have their own learning curve.

[TheCADWhisperer]

Something like this?

[nraynaud]

Thank you for your help,

I can't see the history in your file. 

I would like to shell then draft the road itself, and maybe later make a mold (I don't know yet if I will print and cleanup a positive and make the mold in silicon or directly print the mold in ninjaflex).

I am not sure what you did to the top side, I hope it's not a scaling of the plug side, but an offset. This gave me the idea of testing if the "thinken" function works on the mesh (it's the same thing as shell).

But mostly I'm looking for workflow, not just for someone to do my work.

Nicolas.

[TheCADWhisperer]

I am not a big fan of using someone else's stl files.

In my opinion, these are not even very good files. If they were better - I might spend more time on this.

My recommendation would be to start over from scratch using the existing stl only for reference.

Good luck!

[MichaelAubry]

I think the issue you've been having coming from Recap to Fusion might be this: are your default mesh settings set to triangulate mesh?   If so, (and we need to change this btw as being the default) please kill it:

 

The forum post on the Recap site discusses

If your conversions errors are this then I bet that's the issue:

I've attached the file I've had success with.  With the complexity of the surfaces I don't think you'll have success with draft or shell, but that STL for sure is something we can at least convert. The example I've created shows great potential just using combine.  

Have fun and good luck!

Best,

Mike

[TrippyLighting]

---

@MichaelAubry wrote:

...and we need to change this btw as being the default...

The forum post on the Recap site discusses

 Ohhh,...yes...pleeeeease 😉

[MichaelAubry]

We're working on it.

Michael Aubry
Technology Evangelist - Fusion 360
Manufacturing

MOBILE 503 545 5283
TWITTER @Anonymous_Aubry<>

Autodesk, Inc.
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