PrusaSlicer: strange printing artifacts  

Quick test

Try slowing down speeds 50% as a quick test. Dial speed back mid-print using the front knob. If that helps, you know it's likely related to flow. Add a perimeter and slow external perimeter speeds. Check to see if there is an extrusion multiplier being used in S3D (not sure what they call it) and possibly adjust the same setting in PrusaSlicer. You might want to calibrate Linear Advance for that filament if the preset you're using doesn't include it.

Save your current  3MF project file, zip it up, and attach it to a reply here so we can see your part & settings and give better recommendations.

Ok, thanks! First I will try to print it at 50% at about half of the print time.

S3D indeed has an extrusion multiplier and, as I did with all comparable parameters, it is set up totally the same in PrusaSlicer, to 0.98.

BTW, why linear advance? I really don't like it and I never use it at all with all my printers together with S3D and I always got decent results overs the years so far...

Linear Advance

Linear Advance evens the flow of filament during acceleration and deceleration. It can be hard to spot on smaller prints, but it becomes more apparent with larger prints. It's a firmware feature. The slicer only enables it. You'll see bulges around features and uneven corners if it's too far off. Just set it to 0 to disable it.

File

Posted by: @bobstro

Linear Advance evens the flow of filament during acceleration and deceleration. It can be hard to spot on smaller prints, but it becomes more apparent with larger prints. It's a firmware feature. The slicer only enables it. You'll see bulges around features and uneven corners if it's too far off. Just set it to 0 to disable it.

Did you make that file yourself?  

LA test procedure

Posted by: @cwbullet

Did you make that file yourself?  

Yes. Notes are here. Hopefully, I've fixed all the errors that @ringarn67 noticed!

It's way too big a print to use to calibrate every filament, but it's an interesting test.

Site

Man, that is slick.  I could lost in all of the splendor that is your site.  

Just taking the temp tower concept a bit further

Posted by: @cwbullet

Man, that is slick.  I could lost in all of the splendor that is your site.  

It started out just as a dump for all the stuff I keep learning. I've got an OpenSCAD tower generator to create the various test towers. I just used the temp tower approach and applied it to LA. You can do the same thing with speeds and other settings you want to test.

Sites

I think i am going to start doing the same on my site.  I am 1/2 way through my review of several new products.  I just need some down time to complete them.  

RE: First result...

So, I come back with my first test: slow down speed to 50% during print. The result is exactly the same, see photo. I doubt, that it has something to do with flow, speed or mechanical issues coming from the printer itself. There must be something in the GCode file that leads to those artifacts...

For me, it seems as if it happens during transition between layers with dense/solid infill and lighter infill.

Still need to compare your settings, please save, zip & upload a 3mf project file

Posted by: @pandel

So, I come back with my first test: slow down speed to 50% during print. The result is exactly the same, see photo. I doubt, that it has something to do with flow, speed or mechanical issues coming from the printer itself. There must be something in the GCode file that leads to those artifacts...

How do the prints look if you use the Prusa-supplied presets? You've eliminated a lot of obvious issues by slowing down, so we need to look at what else you've changed.Again, if you save your current  3MF project file, zip it up, and attach it to a reply here so we can see your part & settings and give better recommendations. Otherwise, we have no way of knowing what you've modified. 

For me, it seems as if it happens during transition between layers with dense/solid infill and lighter infill.

There are definite issues, but don't overlook the obvious. For one thing, I see some warping at the bottom right in that pic, and that will exacerbate the problem. Do a quick search for the term "buldge" in these forums and you'll see a lot of discussion on imperfections that can appear on transitions of internal structures. Again, though, I wouldn't go too far down that path until you try a print with one of the Prusa default presets to compare. Not every slicer setting translates directly to another.

RE: PrusaSlicer: strange printing artifacts

I attach the 3MF file. Perhaps you find something.

Just for the record, I am printing for about 6 years now and know about warping, buldge, banding, Z ripple, etc., etc.. That is simply not the case here. I sometimes get warping with S3D GCode, too, and that's due to the fact, that my build plate sometimes isn't sticky enough or when I have an extreme difference between top and bottom layer count, and that's totally ok, as I understand the reasons why.

In this case here, it is different. The lines show up everytime in the same position and they do not with S3D GCode. There must be something different. The only difference I see is, that PrusaSlicer uses relative extruder positioning versus S3D absolute mode. Perhaps I should check that also...

Ah, are you printing on an Ender-3?

Didn't realize you were printing on an Ender-3. Those don't support linear advance in the stock firmware so far as I know. Ignore that suggestion.

I don't see anything unusual in your settings, but I don't have an Ender to test on.

Have you tried the unmodified Creality presets that ship with PrusaSlicer? Do you get different results with those settings?

RE: Nope, on an Anycubic Kossel...

I use the official Anycubic Kossel profiles provided by Prusa, with just some small modifications, reflecting my settings in S3D.

Sorry, could have mentioned that, but as that is a software forum and as I don't have any problems with my printer, I thought that isn't relevant at all - for me, it is all about the results I get from Slicer A compared to Slicer B on the same printer using the same settings.

In general, I wouldn't have asked at all, but I really like PrusaSlicer's features, but want to get the same results as I got with S3D. And therefor I am trying to understand, what's happening if something unusual occurs.

Perhaps I should ignore it and use S3D for now, even though I think that would be really sad! PrusaSlicer seems to be really great and I had some decent results with it the last few days. But if I can not rely on the quality, then it is really a tough decision not to use S3D again...

Look for other delta users here

Posted by: @pandel

I use the official Anycubic Kossel profiles provided by Prusa, with just some small modifications, reflecting my settings in S3D.

Ah, OK. PrusaSlicer has a bug when you import 3MF files with different printers set. It showed a Kossel but the printer profile said Creality.

Sorry, could have mentioned that, but as that is a software forum and as I don't have any problems with my printer, I thought that isn't relevant at all - for me, it is all about the results I get from Slicer A compared to Slicer B on the same printer using the same settings.

That's generally true, but my experience doesn't include Deltas, so I can't really comment on what settings might cause issues. 

[...] Perhaps I should ignore it and use S3D for now, even though I think that would be really sad! PrusaSlicer seems to be really great and I had some decent results with it the last few days. But if I can not rely on the quality, then it is really a tough decision not to use S3D again...

I also paid for S3D. Unfortunately, it seems to have been abandoned over a year ago and PrusaSlicer is under continuous heavy development. I'm not sure what's causing those results, but PrusaSlicer can certainly produce good results. You might ask around to see if you can locate anybody else with a Kossel that can help. I believe @cwbullet has a Predator and uses PrusaSlicer with it.