stl to quad to tspline help

[Anonymous]

First, im not new to modeling. I have been modeling for about 3 years now, ok so somewhat new. I did my solidworks CSWP about 2.5 years ago. However, after i received the cert, i have not used solidworks since because, well, its expensive. I have since been using sketchup pro since then because it works with my brain better than solidworks did.

This doesnt mean i dont like solidworks or parametric modelers, i used SW, pro-e, creo, inventor many times, i just found for me, that sketchup pro worked with my brain. I do know the differences between them as well, such as nurbs etc.

Ok, now that that is out of the way, i need some help with a process. I have to do a case study for one of my upper division materials classes. All i have been given are some stl files. I need to convert said stl files into a quad mesh, then into a brep. The catch is to try and use open source or software like f360 where it is free for non commercial use.

i watched a youtube video where a gentleman used recap photo to create a quad mesh, then to f360, convert to tsplines and then to brep. Im trying to do the same but with instant meshes program. So far i have the mesh inserted into f360, but no idea where to go next to do the last steps. Working with meshes in this way is new to me.

If you know of a better program than instant meshes that works great, also please post that. I cant seem to find a recap photo version anywhere nor one that is free for non commercial.

so, to review my question:

1. ANything better than instant meshes

2. Now that my quad mesh is in f360, how do i convert to tspline, then to brep?

Thank you very much:)

[TrippyLighting]

Can you share the model or at least a screenshot ?

Often for mechancal models that conversion into T-Spines is not really such a good idea.

Once the quad mesh is inserted into Fusion 360, start a new (empty) form. Right-click on the mesh and select Convert.
That should offer conversion into a T-Spline.

When converted, click on finish form. If things go well, then the T-Spline converts into a BRep if it encloses a volume watertight. Otherwise it will convert into a set of stitched NURBS surfaces.

[Anonymous]

Ok, thank you. I will post the stl. The reason i need to convert it, is i
need to do some basic fem on it. And from what i know and heard, is that
triangles are harder to create a smoother surface. This is why i went with
quads.

Is recap photo free for hobbyists like f360?

Thanks. Give me a bit to post the stl. Im at work right now

[jhackney1972]

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@Anonymous wrote:

Is recap photo free for hobbyists like f360?

I will answer this question, NO.  See statement taken from the Autodesk page.

[Anonymous]

ok, its not letting me upload the stl. says its an unsupported type.

1. repaired in meshmixer which destroyed the knuckle joints of the model

2. Retried the repair but in ideamaker, my slicer and it repaiered the file just fine.

3. Exported the file from ideamaker as obj

4. imported into instant meshes and attempted to make a quad. Instant mesh works about 15% of the time

5. wanting to import into f360 to finish the process.  Once it is in f360, i right click on it and there is no convert. However, if i go to create form, then it is there. i think this is what you ment in your first post. I convert to t-spline, but it keeps throwing a error about a body neededing top be repaired. I follow the steps of utilites, repair, and then i select the body, wait 4 minutes, ht auto repair, wait 4 minutes, then hit ok, and then try to hit finish form and it yeilds same error. so auto repair is not fising anything

thanks

[TrippyLighting]

Zip the .stl file, then attach it. 

[Anonymous]

thanks:) here is the zip file containing the original stl, a quad mesh created from instant mesh and one from meshlab

[TrippyLighting]

 This object does not lend itself to remeshing. The outside is of organic shape, but that form is "mixed" with sharp mechnical features. Software such as InstantMeshes or PhotoRecap was not developed forthis type pf purpose. 

Even if you would manage to covert this into a T-Spline, I doubt the results of a FEA woulrd be meaningful.

The mesh has to be repaired as it contains open areas:

The screenshot is from Blender.

Is If you are to create a FEA based on this data set, i might be beter to find a solution taht allows you to generta a tetrahedral (volumetric) mesh for FEA directly from a .stl surface mesh.

[Anonymous]

Thank you for looking at this for me. Its been a struggle to do this. What options or solutions are you thinking of to create the fea mesh?

thanks

[laughingcreek]

did you repair the mesh BEFORE making the quad mesh using insta mesh?  As trippy said, the original mesh has a LOT of errors that should be repaired first.  All your downstream operations are going to be a struggle if you start with a mesh that needs repair.

[Anonymous]

yes, i tried 3 differnt softwares to compare the results for the repair.

1. meshmixer with bad results when it repaird

2. netfabb basic with decent results

3. ideamker with good results

i then exported each repair file and used that in f360. The attached zip folder contains the repaird files. My slicer and netfabb shows them as solids. as in water tight

[laughingcreek]

There are varying  algorithms used for creating a stl mesh from a model.  the one used for this mesh is the typical one, and the worst.  can be difficult to get it to behave.  I took a stab at cleaning it up with mesh mixer and then doing a insta mesh quad conversion.   attached is the result in fusion.  a little bit of time in insta meshes tweaking the mesh output would probably yield improvements.

I'm not sure how useful this will be for using in simulation, that's not my area.

[Anonymous]

how do you use meshmixer to fix the stl mannually like you did?

thanks

[laughingcreek]

I ran a "separate shells", which revealed several little stray bits that I deleted.  then I ran "inspector", and let it auto repair, then I ran "make solid". in make solid I set solid type to accurate and bumped up the solid accuracy, mesh density, and min thickness a bit.

I think there was a spot on one of the knuckles that had to be repaired with delete/fill before the inspector repair would work properly.

Min thickness is the most important setting on this model.  the errors are mostly around where it gets thin where the channels come out at the knuckles.   .8 mm seem to be the sweet spot.

[Anonymous]

i need to learn how to use meshmixer because all i know how to do is hit inspector and auto repair which destroyed the model. I dont think i give as much credit to meshmixer as i should.

Where is this min thickness setting you speak of?

i am going to try and replicate your process to better understand the tools i have at my disposal

Do you know of a good video tutorial that teaches correct principles that relate to this project of mine?

thanks much:)