Trying to import STL and export at STEP/STP

[Anonymous]

I am trying to import my STL design and save it as an STEP. 

In Fusion 360, I convert the mesh to BRep (this even messes up my design, but not the big issue). I then hit export as STEP. This creates a STEP file but when I try to open it on my Mac it says it is a "Document" file and wants to use TextEdit to open, which even that gives an error when I try to open. The STEP file is only 3KB. Opening the STEP file in another program just shows nothing on the screen.

Any help is appreciated, thanks.

[lichtzeichenanlage]

That's such a simple design that I wouldn't even think about converting one messy format into another format (that would result into another messy format because of the source). 

Take some minutes and redraw it quickly in Fusion 360. 

[helibum]

A useful tool for recreating a design is the Project tool in the Sketch menu. You can project any object profile onto a sketch, export the sketch as DXF, and then insert it into your new design, at which point you can do extrusions. I've been working with a design I based off an STL and started getting weird artifacts, prompting me to recreate it. I think I had it completely recreated in about the same amount of time I spent trying to fix the artifact in the original design. I imported multiple projected and exported sketches.

[lichtzeichenanlage]

Why would I export the sketch into a non native Fusion 360 format and than import it into another design. You could a) just create your design in the same project or b) import the sketch into a new design by using the derive function. 

[helibum]

Because I'm still learning the application? I had no idea what the Derive function did. I wanted it in a separate design so that I didn't have to deal with the slow-downs from the original design when rotating or zooming the view. With the OP's object, recreating in the same design may not have been an issue, but my modified STL-based design was getting complex.

[TrippyLighting]

Working with .stl based data in a Fusiosn 360 is generally not a good idea. .stl files contain the least  common denominator of all digital representations of 3D geometry in that they are triangulated meshes and that does not comprise CAD data.

DAC data means mathematically precise surfaces in form of analytical surfaces such as cylinders and spheres or NURBS surfaces which can be arbitrarily curved in space. Mathematically precise means in that they are free of resolution.

Triangulated meshes are of a finite resolution.

When you convert them into a BRep in Fusion 360 each triangular facet is converted into such a mathematically precise object. The max limit is 20.000 faces and if you want to combine solid geometry created by such a conversion than that is very computationally intensive.

While some works for thing such as lower polygon count prismatic objects can be done, once you are dealing with compound curved objects things can dramatically slow down.

[helibum]

I'll definitely lean more toward recreating an object imported from an STL file from now on. Most of the community objects I import are from Thingiverse and the vast majority of those don't include a CAD file. I'd love to see everyone post STEP files with their STLs, but some post SCAD files that are a bit of a pain to convert into STEP files.

[lichtzeichenanlage]

---

@helibum wrote:

Because I'm still learning the application?...

---

That's fine. I'm learning to master this software, too. 

---

@helibum wrote:

.. I wanted it in a separate design so that I didn't have to deal with the slow-downs from the original design when rotating or zooming the view. 

---

My "Why..." was based on the TOs design. It might be a good solution for larger designs. But depending on the design I would still prefer taking measurements instead of projections. But that might be just the inexperienced me.

[lichtzeichenanlage]

If you're searching for *.stp files (or native CAD files) you might want to check out https://grabcad.com/

[helibum]

I'm a member over at grabcad.com. I have pulled a few models from there for checking assembly in my own designs, mainly of Arduinos and Raspberry Pis. You don't find many of the more off-beat/application-specific designs there though.

BTW, I watched a video on YT of the Derive feature and it's pretty slick. One more weapon for my arsenal.

[TrippyLighting]

---

@helibum wrote:

 I watched a video on YT of the Derive feature and it's pretty slick. One more weapon for my arsenal.

---

Yep, but proceed with caution. If you cannot explain the difference between what "inter into current design" and "derive" is then you should not use that feature! 

Id that youtube video does not explain that difference the forget the video!

[helibum]

I hit another snag this evening with an imported and converted STL not joining correctly with my redesign, which was solved by redesigning the STL object as a native Fusion object. It was a pretty simple object, requiring only two projections onto a single sketch and then some creative extrusion. Fusion was reporting non-manifold error messages with the converted STL object.

[jeff_strater]

@helibum - it's entirely possible that there are non-manifold edges in the resulting BRep.  This is one reason why we tend to steer people away from this STL->BRep workflow.  STL and other meshes have no such "manufacturability" requirements built in.  The conversion just creates one BRep face per mesh facet, but does not try to rationalize the result as valid.  You may not find that until later.  I did not see any non-manifold edges in the original STL posted here, but I did not look very hard.  Is it the same STL that you are still working with?  Where do you see these errors?  Can you share your current model here?

Jeff

[helibum]

Here's the STL. I modified it by changing the long outer wall thickness to 3mm on each side (to get rid of the asymmetry) before i attempted to join it to the other body. I first noticed issues with fillets rounding off into a gap instead of filling.

[TrippyLighting]

That .stl after converting it to a BRep is pretty easy to convert into a facet free solid:

[jeff_strater]

thanks for the STL, @helibum , however, the design looks OK to me after conversion to BRep.  I don't see any non-manifold edges.  Can you share your Fusion design here, and maybe a screen shot or screencast of what you are doing when you get this error?  Thanks.

Jeff

[helibum]

I went back to versions before I swapped out the converted STL for a redesigned component and can't get the issue to present itself. I wonder if the recent update might have fixed it.

[lichtzeichenanlage]

The first stl I got, didn't convert nicely. I have to admit that your cleaning process is faster. So it looks like that sometimes redrawing is more effort.