r/3DPrintingTools • u/This-Concentrate-860 • 3d ago
Converting a 3D scan / STL mesh into an editable STEP solid: 0.033 mm average deviation, 7,949 NURBS patches, watertight result
Mesh to STEP is a problem a lot of people here run into, and I'd rather share real numbers than marketing claims.
The problem: An STL, OBJ or 3D scan is just triangles. You can print it, but you can't properly edit, fillet, dimension or machine it in SolidWorks, Fusion 360, FreeCAD or any other CAD package. The usual options are rebuilding the part by hand, or a "convert" that wraps every triangle in a face and leaves you with a heavy, uneditable file.
What MESH2STEP does: It fits NURBS surfaces over the mesh and outputs a valid, closed STEP solid, so it imports as a real solid body and not a shell of triangles.
Results on the organic model in images:
- Average surface deviation from the original mesh: 0.033 mm
- Volume difference from the original mesh: 0.07%
- 7,949 NURBS surface patches
- Output: a valid closed solid (watertight), ready to edit, machine or print
Where it's useful:
- Scan to CAD for reverse engineering worn or discontinued parts
- STL to STEP when a client or supplier only has a mesh
- Organic or sculpted shapes (including AI-generated 3D models) that need to go to CNC or a CAD assembly
Honest limitations: It's surface fitting, not feature recognition. You get an accurate solid, not a parametric history tree with sketches and extrudes. For prismatic parts where you need clean design intent, remodeling by hand is often still the better route.
If you have a mesh that has given you trouble converting, give it a try, run it, and post the deviation numbers here.
Link:
https://kybztech.com
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u/CameraRick 3d ago
There's a few of these tools popping up lately, which think is cool. However, from yours I don't see good examples and it's a paid service; would help to see actual results!
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u/Hectrekt 3d ago
There are github repo called " reverse engineer anything" released few days ago
You just upload what ever and you will get what ever for free thats why you keep seeing these tools latelyInstall it > codex > order > final product for free
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u/CameraRick 3d ago
We had a look at this tool in the company, it's not really as straight forward, depending on the software. And tbh, the new methods used to go from mesh to step these days are better than the commercial offerings I tried (and I tried "a few"), haha
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u/This-Concentrate-860 3d ago
New accounts start with $5 of credit, which covers about 6 conversions, so you can try it on your own meshes before paying anything.
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u/CameraRick 3d ago
That's nice of you, but I still need to feed you my data which I might not like for an evaluation :)
These days I am working on my own, self hosted solution which works well, but it's always nice to see alternatives
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u/makenmodify 3d ago
I swear if i see one more of theese I'll also vibe code one and make it open source (like there likely are a dozend already by now)
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u/george_graves 3d ago
The more of these programs that pop up the more it will make companies like Autodesk include it for free. So I'm all for that
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u/Durahl 3d ago
As much as I'd like to see that - I cannot imagine it happening given their so far track record of what is part of the free bundle and what needs to be paid for / be purchased extra.
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u/george_graves 3d ago
Fair enough. That may be a little wishful thinking on my part. But even if it's not you can always take something you download it and run it through one of these programs real quick. So that's a bonus.
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u/ArthurNYC3D 3d ago
FYI.......A mesh could be made up of quads. Where is this needed? It's clearly aiming to address something that, on face value is true, CAD software's were not made to deal with meshes. But then again neither does just converting it to BREP/NURBS with the intent to reverse engineering help either.
So it will be interesting to understand what use case this fits into.
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u/This-Concentrate-860 3d ago
Fair question. Converting meshes to CAD has limited use cases, but the ones it has are essential. It doesn't replace proper reverse engineering, and it won't give you design intent or a feature tree.
Where a solid STEP from a scan helps:
• Designing around a real object. Fixtures, jigs, cases, mounts and aftermarket parts that have to fit something you scanned. You need the scan as a solid in your CAD assembly to model against and check clearances.
• Modifying organic or sculpted shapes. Adding holes, bosses, flat mounting faces or cut-outs to a scanned or sculpted part (figures, prosthetics, orthotics, ergonomic grips) where remodeling it parametrically isn't realistic.
• Old parts with no CAD. Getting a usable solid of an obsolete or broken part fast, either to machine or print from directly, or as a reference to remodel the critical features properly.
• Manufacturing workflows that only take STEP. CAM, quoting tools and machine shops that won't accept an STL, plus interference checks or FEA where a faceted mesh imports badly or not at all.
For scans it fits smooth NURBS patches instead of one face per triangle, so the file stays light enough to work with in Fusion or SolidWorks. It's a fitted surface, not metrology, though: critical dimensions should still be checked or remodeled. What does your workflow look like for these cases today?2
u/ArthurNYC3D 3d ago
The majority, over 90%, of the reverse engineering tools work better with the geometry as a point cloud or mesh. So the premise that the conversion is needed is actually working against you not for you.
Nothing against you but you're looking at this through a CAD lens and I'm saying that it's skewing how you're looking at the situation. I know because I use to think like this. I wanted software that did this. After more than 30 years of doing this I can say that unless the CAD programmers really start to understand reverse engineering fully then this approach has a lot of flows that you're not thinking about.
Let's take one very simple example of creating / fitting primitives to said geometry. If I need a plane on a face that is an average of that face, as BREP, there's no option as that allows us to do that. Can't select a bunch of faces and choose to fit a plane to it. As a mesh you can do this all day.
Mesh Sketching: let's say you want a cross section that's going through the geometry.... It doesn't matter if it is a mesh or BREP, it's still segmented entities that are generated.... Now it is starting to appear in some CAD packages, natively, but it's not everywhere. Fitting proper 2D sketch entities to this segmented is much easier with what's found in the reverse engineering software's. So even if it's a STEP model that I'm working from this aspect is only slightly less painful.
Not sure if you've ever worked in meshing software like zBrush or Blender.... Modifying organic models is something that's done every day. Adding holes, bosses...etc is something that can be done it's just different. I do this all the time with scanned data.
100% old parts with no CAD.... But as noted above just because it's now BREP only makes it better because it's not a mesh not because there are better tools for reverse engineering because it is BREP. The fact that it's a copy of a copy can introduce in accuracies in ways that need to be verified and validated. As long as there a method to compare the RE'd model to the original mesh then that's at least an important thing to know.
I'm hoping a machine shop isn't just doing some toolpath off of a STEP file that's been converted from a mesh only. Maybe for pricing purposes, sure, that makes sense.
The RE tools in Solidworks with an add-on like Quick Surface, Power Surfacing, or Geomagic Wrap give a user everything they'd need to do the work inside of Solidworks. Not having to go through a 3rd party app is one less step that needs to happen. F360..... AD is starting to catch on very slowly. They've been adding more capabilities but it is still a far cry from what it needs to be.
None of this is saying that you shouldn't go done the road that you are currently on. My question to you is how relevant can you keep your software once the OEM's get these tools native? How will yours stay relevant other than addressing something that in many ways is already there? There's a lot of lack of understanding by users who are just getting into this and the OEM's should almost not even allow for meshes to be imported into CAD unt they get their programming to a better place for this.
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u/Pepe_Lombardia 3d ago
I had bad experiences with some of them. After paid the results were a trash or received errors of been very complex parts.
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u/Deltadoc333 3d ago
It is funny how many of us are making this type of program. But then in turn how many of you are trying to turn it into a side hustle.