3mf and stl, correct me if I'm wrong  

RE: 3mf and stl, correct me if I'm wrong

Not quite correct.  The STL format just stores vertex data.  Ie the points that describe the physical object.
3MF is a more 'modern' format.  It can store many different types of data.  However what data is stored in it is up to the software designer.  There is a standard that they are supposed to follow but again different pieces of software will store different things besides the basics of the object data.

Your modelling software for example 'may' store extra information such as material or colour data for each part.  That doesn't mean that something else loading in your 3mf will understand that data and be able to use it.  At the moment PS wont understand that sort of data as it requires some form of conversion matrix to map it to something PS can understand.

Prusa Slicer for example stores the object data but it also stores all the profile data for your currently in use settings, where the objects are positioned, and modifiers, layer painting, seam painting, supports painting etc etc etc.

None of the formats including 3mf actually store the generated gcode/bgcode.  That is done on the fly when you click slice.  The important thing to remember is that 3MF is just a container and not all 3mf files are equal.

Saving the 3mf from PS is a good idea.  It allows you to load everything back in as it was set up for easy tweaking later.  It is a VERY good habit to get into.

As for using them with Prusa Slicer (or the other slicers based on PS like orca etc).  There is a difference between Open and Load.  When you Open a 3mf you are opening a PROJECT, that means all the settings as well as the model data.  That is generally what you want.

However if you open Prusa Slicer first (so you have your printer/print/filament profiles selected already) and ADD a 3mf file the same way you add a stl from the Plater load object icon then you are only loading in the OBJECT data from the 3mf and NOT the profiles.  Sometimes this is advantageous, sometimes not so be aware of the 2 different methods.

RE: 3mf and stl, correct me if I'm wrong

Thanks for your explanations, it answered many of my questions! However, i have still some confusion left:
do you also suggest exporting the part from Solidworks as an STL? And if yes, why?

RE: 3mf and stl, correct me if I'm wrong

Hi Vera, 
I Don't use Solidworks, 
When I design a model, I retain a copy of that model, for future reference, in the product's native format, so that I can edit it in the future if I wish to make changes, and I export the model as an STL in order to import it into Prusa slicer. 

I Suggest that you also save your models in Solidworks native format (for future modification, and use STL's to pass the models to Slicer. 

STL's can be modified to a degree, but it's a tiresome, process probably best left as a last option...

most 3d design programs seem to have their own unique format, so importing models from one 3d package, to another can be difficult. 

A lot of 3D design packages allow you to export and import STEP Files (.stp) 

I believe that Prusa now offer Step files, in their Github pages, for modern printers. (Older Prusa printer parts were modelled in 'OpenScad' and Prusa offered scad files for people who wanted to modify their printer parts.)

Older Prusa Printers with 8bit processors (up to Mk3s+) used .gcode files, More modern printers with 32bit processors (Mk3.5 onwards) use .bgcode files  (Binary Gcode files) I Believe these bgcode files are more compact than traditional gcode files, resulting in reduced storage space and faster transfer times... 

I Used to be able to read gcode files and make minor changes, I haven't found a way to edit bgcode files...  (Largely due to laziness...) (I haven't found the need to look into the possibility...)

regards Joan

RE: 3mf and stl, correct me if I'm wrong

Posted by: @joantabb

I Used to be able to read gcode files and make minor changes, I haven't found a way to edit bgcode files...  (Largely due to laziness...) (I haven't found the need to look into the possibility...)

Hi Joan, you can convert files between gcode and bgcode with PrusaSlicer via File > Convert > [...]

RE: 3mf and stl, correct me if I'm wrong

JoanTabb's outline is correct .stl files are dumb as rocks. Just triangles making the outer surface of a solid. You need to check your CAD software output resolution settings for .stl and .3mf files. Various terms for this. Coarse, fine, intol/outtol. This defines how close circles, arcs and curved surfaces fit to the triangles. Coarser a hole may visually look like a stop sign and surfaces bumpy. The typical Low Poly model. Fine, visually looks like a circle with smooth surfaces. With 32 gig of memory on my PC, I export all .stl files very fine.

.amf was coming at one point. An advanced Additive Manufacturing File. It may take decades for the industry to fully use an advanced standard, .amf, .3mf or whatever.

RE: 3mf and stl, correct me if I'm wrong

When I design a model, I retain a copy of that model, for future reference, in the product's native format, so that I can edit it in the future if I wish to make changes, and I export the model as an STL in order to import it into Prusa slicer. 

I Suggest that you also save your models in Solidworks native format (for future modification, and use STL's to pass the models to Slicer. 

Thank you! That's how I do it already, I was just insecure because many blogs act as if 3mf is a 1:1 replacement for stl in all uses but I couldn't find out if it was only after slicing or already to export it from the cad. 

thanks to everybody for your answers, I learned a lot <3 

RE: 3mf and stl, correct me if I'm wrong

Well explained by Neophyl!

When 3mf was released there was a lot of fanfare about it being the new "universal" exchange format for 3d models. Alas, it hasn't really lived up to that expectation, as it is designed to allow for slicer-specific information to be added. So it's great if you want to provide specific print setups to others that use the same slicer, but someone with a different slicer may not get that benefit.

When I upload files to Printables I usually put up STL files as the most basic option. I upload 3mf files if I want to suggest specific print settings or model orientation to optimize the print results. Uploading that same 3mf file to MakerWorld may or may not be useful for someone using BambuStudio. There's also the STEP format, which is great if you want to let others modify your model easily as unlike STL it contains a mathematical description of the model that CAD software can easily manipulate. But it doesn't contain any print setting information.

STL — a list of triangles that defines the model. Any slicer can read it.

3MF — the STL plus slicer specific information. Any slicer can read the STL but the extra information may or not be slicer specific.

STEP — a mathematical description of the model. Good for use with CAD software to modify the model. Does not contain the modeling history or any print instructions

CAD original files, e.g. f3D for Autodesk Fusion — Great for that particular CAD program, may or may not be readable  by other CAD software. Contains modeling history.

RE: 3mf and stl, correct me if I'm wrong

I typically use .step files for between my CAD and Slicer. This is for several reasons.

First, community remixing: With shared models I find .step is easier to remix an existing design (in my experience using primarily parametric solid modelers (like FreeCAD) instead of mesh modeler's (like Blender)). I also provide my original CAD file, but I recognize that others may not want to bother downloading and learning the quirks of FreeCAD so the .step is a backup for remixing.

Second, compatible with modern slicers: From what I can tell, all (or most) modern slicers can import .step files and take care of tessellation (converting from solid models to a mesh of polygons) at import. I don't have to think about how fine to make my mesh at export from CAD. I like curves to print without obvious facets. This helps with accuracy of dimensions and allows the slicer to use curve gcodes (if the slicer supports this) instead of many small line segment gcodes to help reduce gcode file sizes. Many slicers offer the fine-ness of tessellation during import. (My experience is solely with PrusaSlicer, but I've heard in forum others talking that other slicers do this as well. Especially the many PrusaSlicer derived slicers like BambuStudio and OrcaSlicer and their derivatives/vendor skinned version.)

Third, file size: In my experience, a .step file is often smaller than a .stl file of the same object, especially if there are any curved features (fillets, round holes, etc). I'm old enough to remember the "buck-a-meg" sales on hard drives for 50 to 200 megabyte sized hard drives, 880Kb floppies (Amiga), and metered internet connections so my file size reduction habits are well ingrained.

But this is just my opinion. Just remember, opinions are like assholes. Everyone has one and thinks theirs doesn't smell bad. 😉