Convert Surface to Solid

[Anonymous]

Ok, I give up.

I need to manipulate a mesh body.  I've been working on it for HOURS...reading threads here and elsewhere, and also trying whatever I could think of on my own (I've been doing simple CAD work for many years).  None of the several suggested processed I've followed have worked so far and I'm exceptionally frustrated.

In an empty design, I inserted an STL of a hummingbird. It's a surface only, not a solid, with about 250k faces. I got it from reputable source for use in a CNC router project. I'd really like to convert my CNC processes over to Fusion 360 if possible.

I simply want to move the mesh body to the ground. In the process of inserting, there is an option to do so (both center and move to ground). But after the insertion is complete that option no longer exists.  Why can't I simply select the body, select MOVE, specify "point-to-position" and move it to [0,0,0]?  Better yet, why can't I simply "move to ground" after insertion?  If it can be done "during" insertion, why not "after"?

I tried simply "moving" it.  I can free translate it, but that's not exact. I can't seem to select any edges or points on the body to move it exactly to [0,0,0].

So I tried converting it to a solid.  Reduce the face count to < 10k, convert mesh to Brep. It's still just a surface, not a solid.  To make it a solid, I tried boundary fill (when I attempt to select a "cell" part of the surface, but not all of it, disappears).  Thicken doesn't seem to be the answer.  Stitch isn't it.  Building a box around it and joining/intersecting/etc. won't work (because the bird isn't a solid body).  Everything seems to work only for solid bodies.  I can't select specific points on a mesh and I can't convert the mesh to a solid.  So I'm at a dead end.

I understand that Fusion 360 can be used to design everything from micro circuits to space shuttles.  Why can't I simply move this bird to ground?  What simple thing am I missing?

Thankful for any advice.  I don't know how to include a file for you, but if that's necessary, give me some hint and I'll go try to figure that out.

[davebYYPCU]

Are you saying, insert to ground, when inserting, did not work?

If it does work, do that.  I would imagine the Fusion team added that to avoid your problem.

Manipulating? Use external Software, bring it in when machine ready.

Converting - still a surface, if it was manifold it will be a solid.

Your happy with < 10k faces?

You did answer your own question, Fusion doesn’t play well with STL.

Attempting to use STL other than for output, is a time soaker.

Might help....

[TrippyLighting]

.stl files contain triangulated meshes, the least common denominator of all forms of 3D geometry representation.

triangulated meshes lack topology in a mathematical sense and are of limited resolution.

CAD software including Fusion 360 represents geometry as BRep which can include NURBS surfaces.

This is a mathematically precise representation, free of resolution and with topology. This is the opposite end of the spectrum.

When you attempt to convert a .stl mesh into a BRep, every facet of that mesh is going to be converted into such a NURBS surface. That's the reason the limit of 20k polygons exists.

NURBS geometry is computationally more demanding than a mesh.

There are methods that can help to convert triangulated meshes back into NURBS surfaces, but often that goes along with loss of detail or requires a good bit of experience.

[TheCADWhisperer]

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@Anonymous wrote:

Ok, I give up.

I got it from reputable source...

I don't know how to include a file for you, but if that's necessary, give me some hint and I'll go try to figure that out.

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I recommend that you create your own geometry rather than using someone else's mesh (subtle pun intended).

In any case, Attach the original *.stl or File>Export and then Attach the *.f3d file here (I would prefer the original stl file.)

[Anonymous]

daveb: thx for the thoughts.  Move to ground works while inserting.  But after inserting there is no option to do that.  So the steps are:

1. insert to ground.

2. manipulate (scale, move, etc.) the stl object, such that it's no longer on ground.

3. now I can't move it exactly to ground.

Yes, in this case, 10k faces will work just fine.

[Anonymous]

TrippyLighting:  Thanks for the insights on the mechanics of stl and other shape geometries.  I did read much of that in my research, hence my stabs at reducing faces, converting to Brep, etc.

Through my reading of this forum over the last year, I know you are an expert and have answered thousands of questions.  So I appreciate you addressing mine.

I use F360 for design of woodworking projects (e.g. tables, etc.). I use VCarve for CNC design.  I'd like to convert to F360 for the CNC design also, so that I only need to be concerned with one app.  But if F360 can't handle the stl objects involved in 3d relief carving, then it's not going to be useful for my CNC process.

Couple thoughts:  Are you saying that F360 isn't good for what I want to do and I should stick with VCarve for CNC project design?  Or is F360 the way to go, but I need to do something differently?  BTW, I'm rooting for F360...

thanks again.

[Anonymous]

CAEWhisperer:  Thanks for the advice.  I appreciate you answering my post.

Unfortunately...I don't have the artistic skill to create a 3D object of a hummingbird design.  So I purchase the design in STL format for my use.

Of course, this is done everyday by designers everywhere and that's why STL files are available for sale (and available freely in many cases).  Therefore I feel like it should be simpler, especially for a product with the deep capabilities of F360.  I feel like I'm missing something simple.  If I need to just stick with VCarve to handle CNC project design, then I'll do that, but I was hoping to convert that whole process over to F360.

thanks again.  Attempting to attach the STL file...

[TheCADWhisperer]

Do you realize that this is only straight lines and triangular planar facets - no curved surfaces?

(Also, it is only single side - does not form a closed "envelope" volume.)

[william-c-anderson]

@Anonymous , I was able to convert your STL file into STEP (using an eval copy of CAD Exchanger) , but the 12 MByte file grew in size to over 400 MByte. I was of course able to directly import the STL into F360, but the mesh was over an order of magnitude too large for F360 to manage. I tried importing the converted STEP file, but F360 "thought about it" for over 15 minutes, and I gave up before F360 did. My assessment: this kind of file is not a good fit for a parametric mCAD program like F360. There may be other ADSK product that are a better fit, I don't know. I do know that Meshmixer has no problem with the STL file.

Having said that, the arbitrary limit to the number of facets that F360 sets on an imported mesh (when converting to BREP) should be a user-defined parameter, IMO. Is there some good reason that this limit is hard-coded? I've just spent several days converting an STL representation of a 3D printer into a micron-exact F360 model, and I've converted dozens of STL files into BREPS and then into clean models; I've got a pretty good idea of the workflow. F360 could be a lot more helpful with STL than it is currently. Just my 2¢...

[Anonymous]

CADWhisperer, Hey.

Yes, indeed, I do realize it's triangles and planar facets. I reduced the original count of 250k facets to 10k before converting to Brep.

And yes, it's single-sided, i.e. a hollow surface, and not a solid. Which, therein, lies part of my problem.  That's why I attempted to make it a solid through Boundary Fill, intersecting it with a cube, etc.  Unfortunately none of those attempts worked.

[Anonymous]

William-c:

Thanks for the attempts and the time you invested in that.

I'm aware of Meshmixer, but don't have any experience with it.  Will Meshmixer allow me to convert the STL to a solid?  If so, would F360 then be able to handle that more easily?  I would be able to grab a point on the solid and move it to an exact location?  It would mill on the CNC router in 3D relief just like a surface mesh? Etc.

thx.

[william-c-anderson]

@Anonymous , no problem. Not much time invested, as I've become pretty adept at importing STL to F360.

I reiterate that I believe this type of model is a "bad fit" for F360 - F360 is for mCAD, not organic surface modeling. Standard solid data structures (e.g. BREPs) are not a good fit for very high facet count, "organic" shapes, IMO.

Meshmixer (an ADSK product) claims to be able to "solidify" this file, but it crashes when I try it. YMMV.

[Anonymous]

Got it, thanks.

[TheCADWhisperer]

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@william-c-anderson wrote:

I reiterate that I believe this type of model is a "bad fit" for F360 - F360 is for mCAD, not organic surface modeling. .

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I have seen @PhilProcarioJr do some pretty organic stuff with Fusion.

No planar facets here...

[Anonymous]

Ah...that's what I'm trying to do.

It seems I shall have to request a lesson from @PhilProcarioJr .

thx again.

[TheCADWhisperer]

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@Anonymous wrote:

It seems I shall have to request a lesson from @PhilProcarioJr .

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Here you go >> a lesson from<<@PhilProcarioJr.

[Anonymous]

Thank you. I will take a look.

[davebYYPCU]

I think you missed my point, 

Meshmixer will do the (manipulate scale move etc) preliminary work, 

when imported, no design work, straight to Manufacture for setups.

I see you have been introduced to T-Spline, 

I’ll presume you are not happy with 10 k faces.

Might help...

[PhilProcarioJr]

@Anonymous 

You might also want to look at this thread...

what-is-really-possible-with-t-splines

Cheers,

Phil

[Anonymous]

Yes, on any given day...it's very possible that I missed the point...haha.

I've downloaded Meshmixer and made a couple attempts to get the STL converted to something I can import into F360.  No success yet, but I'm still learning on that process.  I guess I'll have to go study Meshmixer for a while to figure out that workflow.

Is it like this?: import STL into Meshmixer, then somehow convert it to another format, then export/save that conversion, then import that converted object into F360?  Right?

Couple things are for sure...because I don't have the artistic talent (or patience)...I won't be drawing a hummingbird, nor will I be building up thousands of quads over the hummingbird mesh I've imported.  I don't really want to design a hummingbird, I want to import one for use in a larger CNC router project.  Maybe part of a picture frame, or top of a box, or something like that.  I'm amazed by people who can do that kind of blank-page design work, but that will never be me.

In this case, for this hummingbird, at the size I need it, 10k faces were ok.  Although, that seems limited for more complex designs.

Again, I appreciate your help and patience.