Never seen this ????  

RE: Never seen this ????

Sorry its not easy to understand.  What exactly is the issue ?  Or what are you trying to do ?

The last pic is just a slice with the surface not flat to the bed, so the part thats touching slices on the first layer and then the rest is on the second layer as the surface is tilted.  Either use the place to face tool, trim the bottom so its flat or slightly sink the object down by a layers worth if you want it to be flat to the bed.

I cant tell at all what you are doing with all those pics of cuts though.

RE: Never seen this ????

Are you showing us non-parallel surfaces that vary less than the layer thickness? That doesn't have full coverage on a first layer? Tolerance in processing kicks in and things go funny. I have run into this before with models that the author didn't check well. I adjust them down in Z at .01mm increments until everything printed on the first layer. Depends on the part how much you have to adjust.

RE: Never seen this ????

Sorry its not easy to understand.  What exactly is the issue ? 

ok so what i did  :  just took a STL files using the cut tools add connector then slice..as you can see there is only 1 flat white part so normaly it can have 2 different levels !!  as i cut with the slicer so 1 cut but apparently with the number of polygon that appears this sometimes, for me the 1st

RE: Never seen this ????

Might be a language thing but I'm still not following what the issue is.  

Just zip up and attach your prusa slicer project file (File>Save Project as, then zip the .3mf file created) so people can see what you are working with and then explain in vert simple steps and words what exactly its not doing that you think it should.

RE: Never seen this ????

hum je te la fais en français , comme google est partout je suis certain que ça sera plus facile ... et moi je ne comprends pas ce que tu ne comprends pas !!

tu prends une grosse pièce STL tu l'importes dans le slicer , tu prends l'outil "couper" ou la lettre C de ton clavier . tu coupes ta pièce où tu veux. Donc à ce moment-là tu retrouves avec 1 ou 2 pièces ? jusque-là tu me suis ? et donc lorsque tu coupes avec l'outil "couper" tu dois obligatoirement avoir 1 seul plan ? donc 1 seule marque blanche ou 1 seule face !! oui ? ok

Donc quand j'ai fait le tranchage donc slicer , je me suis retrouvé avec la photo que tu vois + haut . donc forcément un surplomb qui ne devrait et ne pourrait pas exister puisque j'ai coupé la pièce ...

Mais c'est une histoire de polygone qui est en trop grand nombre et donc le slicer prusa n'arrive pas à tout calculer et il manque des polygones ...

cela ne fonctionne que sur des grosses pièces , car beaucoup de polygones alors..

RE: Never seen this ????

Again I've never come across that.  This is why we ask people to attach a saved prusa slicer project file.  That way we are working from the same models and the same settings.

RE: Never seen this ????

Again I've never come across that.

me either 1st in my printer life.. the 3mf or whatever files won't give you more than the pics..i add on 1st post it was more an info than screaming 😆 you can try on your own ..i usualy never cut so big part ..and i have to add that was only for this big part, the other big part i didn't have this weird issue..but just becareful and control the bottom after slicing..

RE: Never seen this ????

Yes the 3mf will give further clues.  If your theory is that its based on model complexity then it gives the same model and settings so in theory someone else should get identical results.  Its called testing.  I have cut plenty of large objects, and have not seen the problem.  Using various slicers and Prusa Slicer all the way back to before it was prusa slicer.  We don't ask for the files out of fun generally. Its the minimum needed to track down potential issues.

It could also be the model geometry is malformed and that when cutting spurious verts are left which are confusing things.  Again the 3mf project will have the geometry in.  Without it anything is a complete guess, even if an educated one.  If you report an issue with the slicer on the github the devs will also need the project file.  Its the primary way of debugging issues.