The people i work with use all kind of different 3d programs, which is fine but the problem is exchanging files. It would be great if I somehow I could mesh export to STP (step) files.
I am using blender 2.8 most likely it would require another program / website…
But i’ve been looking around quite a long time to get this done, and sofar had no luck.
Does anyone here now a way that works (preferably free, as its only mesh conversion that i’m after, so i dont wanting to invest a lot in an expensive program which i then would only use for conversions).
I tried Blender 2.81 > dae export > freecad 0.18 , but it doesnt work
Direct conversion of a mesh to STP is typically unusable (where each triangle becomes a flat nurbs surface). Typically a smooth nurbs surface is desired, not facets.
The reason for requiring STP or other nurbs format is typically for CNC machining or CFD/FEA analysis.
The infinitely smooth nurbs surface may be optimally meshed by these applications. A model where the triangles are converted to flat nurbs facets would not produce the correct results.
I don’t believe you will find software that can create a STEP file from a mesh for the general case. STEP files are used to import/export parametric models and assemblies. The issue is programs like Blender, Maya, etc. create meshes. The meshes are infinitely thin surfaces that completely enclose the mesh object. By comparison, programs like SolidWorks, Creo, Inventor, etc. create parametric solids. These are composed of mathematically defined features. As an example for a very simple case, consider a sphere. A sphere in a mesh modeler like Blender is composed of many triangular polygons enclosing a spherical volume. A sphere in a parametric modeler like SolidWorks is a mathematical construct that defines its diameter. No matter how far you zoom in, it will always be displayed as a smooth sphere. By comparison, for a mesh sphere, if you zoom in far enough, the faces will be visible–if smoothing is off. Smoothing is an algorithm that uses the normals of adjacent faces to present a smoother view, effectively hiding the sharp edges between faces.
Although conversion from a mesh to a parametric solid (so it could be exported as a STEP file) may not be possible in general, it can be done for simple cases. See the image below that shows a rectangular solid with a cylindrical hole in it in Blender and Alibre. Alibre is an inexpensive parametric modeler that included a mesh to parametric converter through the 2018 version. As you can see in the image, even for this simple case, the conversion is not perfect. The converter has been removed from more recent versions because of the limitations of the conversion.
Having to work with CAM people and its problematic to use Blender, (but from another design point i have to use it) , the program i mentioned earlier isnt ideal, it creates meshes instead of dril holes, I think to solve this a developer should look at hard surface modelling, this workflow might be expandable in the same way step files are (quite literally readable) alterations on a shape on a step by step order. (each modifier is a row in a step file (or for repeated tasks multiple rows)
Then the bevel operator with all its parameters set would be like rounding r on edge x
A cylinderic boolean minus operation would be alike at pos x,y,z drill hole radius r depth d
There is software that can do this, It costs $15,000 or so and requires a properly trained user. Google DesignX if you are interested.
I don’t see any one developing an open source alternative for this because the coding demands go far beyond what a single person could produce.
I keep thinking that an extension to blender might not be that complex to code (at least for basic operations) since all action in hard surface modelling, are just as the line rows of a step file opened in notepad, but some extra logging would be required.
Say one created a cyclinder and then do a boolean, then one only needs to record clinder radius and lenght, and if it was boolean substracted.
If one would create a mirror of 2 cylindes, its easy as wel, log that one created a cylinder from its origin duplicate and if then a boolean happens in the hiearchical order of action add or substract. dont think the STEP format would be that complex to add in code.
If you are only concerned with cylinder, then that would simply things significantly. Cloud Compare has features detection/ extraction for cylinders and planes.
Well mostly it are bevel operations and angled cubes , ea not human models.
The typical forms of hard surface modeling, and thats why i believe it should be possible to directly export those actions to a step file.
Maybe just for the case a new type of object (like we have metaballs) objects who have a limited set of modifiers (but overtime it can extend).
It would be really great for all those who work in 3d manufacturing beyond 3d printers.
So far that’s a 3d realm not touched by Blender. I think a lot of engineers would want this in Blender.
Typically CNC doesnt use STL, they use DXF, STEP, IGES those formats better translate to Gcode then triangle formats such as STL, OBJ, Blend, some programs such as freecad can convert formats but not optimal (they still keep it as a typical blender triangle file).
Some CNC devices might accept STL, they will approximate holes and bevels as in blender then, which is not optimal, ea if it finds a blender bevel to them its striaght surfaces while instead it should understand its a bevel and thus apply a different toolhead to a milling machine. STL cannot reflect that, neither OBJ, in contrast the (auto)CAD type files (including STEP and IGES) do.
But with some workaround it’s possible, but a bit hard… Moi3d v4 can convert subdivision surfaces into NURBS surfaces, and with a bit of work even FreeCAD and FreeShip has the ability to convert mesh subdivison into NURBS. anyway if he need a control maybe the best way is the modelling of that directly in CAD software.
In fact I’m working with Blender as a fast concept design and then I use CAD to finalize my project, but Blender is awesome and fast, no one other has this capability.
This video below show my old model created into blender and imported in CATIA for a milling. the Subdision conversion was made with Fusion360, when it was free.
It is now only free for non-commercial use. There previously was free commercial usage for income below a certain amount. This licensing expired around the end of Nov 2019.
I do consider that… when things cannot be done cheaper in metal CAM then 3d print
The point is that i’d like that blender would expand in this area, i’m not waiting for the next fbx converter but rather would have the real standard in this STEP, based upon blenders procedural hard surface modeling work flow
Sorry but here I think you can already consider this as a dream, it is 15 years if not more that we talk about these topics, for now no one has ever come to get your hands on this part of Blender, so I would not want to destroy the your expectations but you’d better get with paid software like I did if you have this need. Or maybe use FreeCAD or also others you like.
some topics where we started discussion about that…
A recent illusion from these guy
And I remember that there was also a fundraiser to start a project that died.
