Warping in Prusa Slicer before bridging, not for S3D  

Rapid cooling is a major cause of warping.  

Also the best way to debug issues is for you to save your problematic project (File>Save Project as) and then take the 3mf file and zip it up.  Needs to be zipped up for the forum to accept it (unless the recent changes have removed that restriction).

Once we have your project we can slice with exactly the same settings you are using and see exactly what is happening as the project contains a snapshot of all settings as well as models etc.

RE: Warping in Prusa Slicer before bridging, not for S3D

Rapid cooling as in: "Cooling to fast or fan runs at full speed" ?

As a total beginner of this Slicer I haven't completely understood the concept of the cooling settings...in S3D you just specify PWM % per layer...that's it...

Maybe the PLA isn't the best one I chose for testing..it is the cheapest one...but both colors are of same brand....

So next step for tomorrow: Load a better PLA and slice/print it again.....and upload the project zip (wasn't aware this was possible).

But from my first impression...just a great slicer software...though loads to learn still (o;

RE: Warping in Prusa Slicer before bridging, not for S3D

Tried now with a better PLA.....and cut the object a little to only print the specific section...but had to cancel the job as when the nozzle moved it caused the object to be loosened.

Attached the project file...

no project file attached, you did zip it up didnt you ?

Theres 2 factors really that I wanted to look at in the project, you mentioned that PS was printing those areas slower than S3D, thats quite possible as there are various settings that could cause that.  If it prints those areas slower with full cooling then thats going to be rapid cooling 🙂  By checking the project with the preview in speed mode we can see what speeds its using etc.

RE: Warping in Prusa Slicer before bridging, not for S3D

Oops....I did attach it in the previous answer....odd....had to edit this answer and add it a second time until it showed up...

Those areas are naturally going to curl up as they are overhangs.  Having the model firmly attached usually allows the printing to survive any slight raising and the nozzle will 'iron' it back down usually in those cases.   

One of the (current) bad things about PS is the logic it uses for bridges.  If you notice it assumes that any bridge is printed with a layer height equal to the extrusion width.  While this is technically the case as it has nothing to squish against on the layer below I personally think it can cause its own issues.  I have this strange tendency to see where it puts the dark blue and then make my own decision on if it needs support and then I turn OFF detect bridging to force it not to use bridging IF I think the model will print without it.

On this model I think thats the case.  Hopefully attached is a modified version of your project.  I'm not able to print anything this evening otherwise Id test it on my mk3 but this is how I would try it first.  Basically I've tweaked the settings to keep the print speed fairly constant.

PS2.4 is supposed to have an option in to turn off the bridge flow logic but still keep the bridge detection (and therefore speed/cooling etc) for those areas.  That along with the support changes are what I'm really looking forward to trying, its the wait that's hard lol.

If it doesn't print like that then I would be looking at either reducing the cooling in those spots or slowing it right down on those spots so that its solidly cooled before it moves away.  That would mean playing with the layer cooling settings that are normally turned on that you currently have disabled on your filament profile.