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Oh gosh. There is a different minimum layer height for bigger nozzles. I'm not sure what it is for .8mm nozzle. .15mm layer height should be fine. I'm not sure if it can go down to 0.1mm layer height and still have as good quality. I'd print a tiny test print - maybe a 2cm cube with a slightly tilted top. I think it might be fine but I'd test it first.

The lastest versions of Cura are designed to work with any printer including some really obscure printers from China. I don't think there is such a correlation. I see you have a UM3 which is the most complicated as far as cura is concerned. You should be able to have the original firmware installed that came with your UM3 and it should be fine with Cura 5.3.0. Personally I don't update firmware unless there is a really good reason. And that means some of my printers sometimes have 5 year old firmware. My Um3 certainly has pretty old firmware. Or am I missing something? Some new feature that has a new kind of gcode that older printers won't recognize? Nothing I can think of.

If this works great for this print. And the next. And the next. But then a few months from now you have a print that keeps failing - remember that you set this to 100 and maybe lower that back to 25 just to see if it it's grinding the filament to dust at one particular spot when you actually have 100 retractions in just 1mm of extrusion. You can indeed get this when you have tons of tiny islands like when printing the legs of the eiffel tower - there are many hundreds of tiny tiny girders and each one is a tiny point on a given layer. I suspect 100 is safe enough but I really don't know where the problem occurs. If my memory is correct (and it was like 10 years ago) I was able to do 60 retractions safely per mm but 120 retractions was too much. but that was a different feeder (on the original UM2) and may grind filament more. Or may grind filament less. than the S5. I do remember that I used "grep" to count how many retractions I had and it was something like 2 kilometers of retractions! In one 18 hours print! Wow.

Are you talking about the staircase steps nature of your curved top surface? If so then you need to decrease your layer height. I can't quite read your layer height but I think it says 0.4mm? You can reduce that to 0.1 and still get good quality. The limit (before you get diminishing returns) is around .06 or .08mm (less than 0.1mm - I clarify as people often accidentally add or remove a zero, including me). But 0.1mm layer height will print 4X slower than .4mm layer height. So there is another option - you can do thicker layers up until your first "top" layer at the bottom of that curve by using adaptive layers. Check that box. If you want layer heights to be .4mm in the bottom portion (to save hours of time) and the thinnest layers to be .1mm then you need to find the average and difference of those two values. The difference is .3mm and the average is .25mm. So in this example (.1 to .4) set the layer height to 0.25 and set the adaptive layers maximum variation to .15mm. ironing will only smooth each of those flat "steps" in your image above. And it will waste lots of time. You have so many steps that I think ironing is probably not worth the extra print time. You can experiment and decide. Ironing is tricky and you may have to play with the parameters a lot to get best results so if you play with ironing you should do it on a small part first (say 2cm by 2cm by 5mm tall). By the way, all the yellow shown in your picture are thought as "top skin" or "top layers" by cura. Each and are thought of as separate surfaces - separate layers. Cura tends to mostly think of one slice at a time. So when it is doing that middle yellow strip that portion is a "top" (aka skin) layer and then there are other portions of that layer that are not skin which will be other colors (but hidden from this view by layers above).

@tryptamine - this is really good analysis and very helpful. But it probably will be ignored unless you create a github issue. Please please do so! You have to create a github account if you don't already have one. Then the next step is easy - just create an issue here: https://github.com/Ultimaker/Cura/issues Click that green button. Please include your 3mf files and your excellent photos for the 2 bugs. Maybe post them separately but they may actually be related. Well, maybe not. But should probably be both fixed by the same programmer. You can either make 2 issues (and maybe link to each other) or you can make one issue and let the cura devs split it into two if they want to. I guess it's best if you create 2 issues.

You say "discontinuous on each layer". I think I know this bug. I referred to it earier. Basically it is going around clockwise and then when it changes layer it backs up a cm or so? If so then this is a known bug and I think it eventually got fixed but I don't know which version. I see this in the release notes for version 4.8: Fix off-by-one error that could cause horizontal faces to shift one layer upwards. So maybe it was fixed in 4.8? I'm not sure if this is what they mean but I definitely remember the bug where, when it changes layers, it jumps backwards by quite a bit. Very annoying. Especially when spiralize was on. Basically when it finishes a layer it has to start the new layer somewhere and it tries to start it at the closest intersection. But there was an off-by-one bug or something that made it go back to the previous intersection above where it finished the layer below. Which may be a few mm away or 100mm away depending on the model.

What is the jerk speed? I guess you have to lower it? That initial jerk puts extra acceleration into the first half of the vibration - the first .75mm of travel. So lower the jerk speed as well I guess? I don't know how to deal with that - you want a lower accel in the first .75mm and then much higher accel in the second half so the speed increase is equal in both halves of a ring: 35mm/sec in the first .75mm and another 35mm/sec (to reach 70mm/sec) in the second half. But that would require adding an extra point along the travel (where it increases acceleration .75mm along the path). I don't know if Cura does that for you or it just lowers the jerk a lot (say to 10mm/sec?). I don't really know. I guess if cura did it for you they wouldn't have to lower the acceleration at all. They'd just set the speed for the first .75mm to 35mm/sec and leave jerk and accel high. Then the remaining travel would be to 70mm/sec. That would force the total acceleration in the first and second .75mm to be equal which would cancel out the ringing. Well the S5 has a big heavy print head with heavy 8mm rods passing through it which add more inertia. And the belts are the same size as the smaller printers like the UM2. So it just has a lot more ringing. UM engineers were used to bowden printers with super light print heads but when they went dual nozzle they ended up with a heavier head and they did some kind of accel/jerk hack but I don't know how well that works as I don't think it breaks up the move into two segments. I don't know what the heck they did. Probably just lowered the jerk a lot and did the acceleration calculation that we just did. I'm curious what accel and jerk settings are inserted into the gcode when you enable jerk and accel control.

log file is here: %APPDATA%\cura\<Cura version>\cura.log (Windows), or usually C:\Users\\<your username>\AppData\Roaming\cura\<Cura version>\cura.log $USER/Library/Application Support/cura/<Cura version>/cura.log (OSX) $USER/.local/share/cura/<Cura version>/cura.log (Ubuntu/Linux) I assume the config folder is nearby

Indirectly, yes. I think it's: maximum retraction count This prevents you from doing so many retractions in the same spot of filament that you grind the filament to dust. I think it defaults to 25. Try increasing it to 100. If you get a print failure where the filament is ground down and the feeder stops feeding - and if you remove the filament you see it has a big bite taken out of it - then you set that value too high. You could reduce the feeder pressure a little but that might make grinding worse in other sections of the print. I suspect if you only increase the 25 to 100 it will be fine. In other words, the printer likes to advance the filament X mms before retracting more than Y times. The defaults I think are 1mm and 25 retractions. So if you do more than 25 retractions on the same 1mm of filament the software says that's the limit. Y is the bold setting above. X is the bold setting below. Only mess with one of these settings. Either increase the one above or decrease the one below. Don't do both. I would just mess with the one above but I'm showing that they interact for a fuller explanation. minimum extrusion distance window Alternatively, you might not want to mess with this setting and just live with a few non-retracting travels. Personally I'd increase it to at least 50.

Those red/green/blue blocks are arrows. Click on the arrow you want for which direction you want to mirror. I mean you can click on any of the 6 arrows but it's faster (no rotations needed) if you choose a green or red one. It works the same way as the scaling and the moving tools. Actually, once you see the red/green/blue arrows, right click anywhere on the 3d display and drag so that you can orbit around your part. Once you start orbiting, the 3d nature of those "blocks" becomes more apparent.

I'm pretty sure you can do it. First read this and practice changing infill: https://support.makerbot.com/s/article/1667417981430 Then realize: Top and bottom layers are not infill. They are skin. I don't think you can change the skin pattern but... Make a mesh modifier for where you want it be concentric (so one for the top and one for the bottom and more for other areas of your part if you want): In the mesh modifier (and probably also for the entire part), get rid of the top and bottom "skin" layers. Then set the wall thickness to 1 meter (any value bigger than your part size will work). That should do it. It depends what your part looks like. If it's a sphere this won't work well. If it's a cube, then: easy.

By the way, I think the way you remove ringing is really cool. So UM printers have high accel. I think S5 has 5000m/s/s. So if printing speed is 150mm/sec it takes 30ms to get up to full speed. Printing at 70mm/sec takes about half that or 14ms. It's actually faster as the jerk allows you to start at around 14mm/sec before you even start accelerating. At these accelerations you are 150mm/sec in 2.25mm of distance (distance = 1/2 * accel * t^2). Whereas the ringing frequency is usually slower? I think? That is what people tell me. This greatly simplifies the analysis. So you first calculate the period of the ringing. You can do that by measuring the distance between the bumps - do it where you know it is at full speed (2.25mm from the corner if at 5m/s/s accel and 150mm/sec printing speed - closer to the corner if printing slower - farther from corner if accel is slower). Then if the period is say, 30ms, and accel lasting 14ms you can see that all the acceleration is going into the first half of the oscillating cycle. Which creates the most possible ringing. But you want the acceleration to last exactly 30ms if that is the ringing period. So you pick an acceleration that means it will take 30ms to get up to full speed. That will result in zero ringing. speedup time is speed/accel.

That's the tradeoff. The default S5 acceleration and jerk settings fix the ringing but then you get those bulging corners. You can fix one or the other. That's why there is the "engineering" profile which has lots of ringing but parts are much more accurate when measured with a micrometer. And the regular profile which has nicer looking parts (not much ringing). the one way to fix both issues is to print slower. 35mm/sec is pretty good but you can even go as slow as 25mm/sec. Personally, for what I do (print mechanical parts for customers), no one cares about the ringing but accuracy is very important so I use the engineering profiles.

I'm guessing they have a different machine profile loaded than you do. With the project file, the machine profile is included inside.

I've given up on profiles. I've had better luck with project ilfes. Ask the person who created the cura profile to instead create a project file. It doesn't need to have any objects loaded. that will save the machine settings, profiles, and cura settings overridden. Tell them to do "file" "save project..." and send you the resulting file.

If you click on an object loaded into cura, on the left side are move tool, scale tool, and mirror tool. Use the mirror tool.

Yes. Dark blue has no retraction and will string. Dark blue travels are normal and fine for *inside* the walls of your building but those that span an air gap in a window or doorway you want light blue. In certain cases you also want to disable retractions inside an "island" as cura thinks of it. Inside of a wall in your case. Those are controlled with "combing" but I think you want to ignore combing because your issue is across gaps (windows/doorways).

In cura, above the settings, there is a search box. Enter "retractions" and there are various minimum and maximums and such. I'd play with those until it's light blue.

If you look in PREVIEW mode at your sliced model in cura, set the view mode to "line type" and make sure the "travels" are checked (blue). The travel moves come in two colors - light blue and strong/saturated blue. Light blue is a retraction move. darker blue (as shown in MariMakes photo) is non retracting. There are quite a few settings that can control which type is chosen so if you have this problem again, check the blue colors and then look at all the retraction settings.

PLA is usually pretty good about not stringing. Unlike some other materials which need to be dried to avoid the stringing. Are they extremely fine hairs that are hard to see? Those are the hardest to get rid of by messing with settings but the easiest to get rid of after the print is done. I get rid of most of those with a flame. I use a butane torch - around $10 on amazon. I give the strings a quick swipe covering maybe 5 inches per second so each spot gets only maybe 30ms of flame. No. Faster than that. Maybe 15 inches per second. The fine hairs are then gone. If you move the flame too slowly you brown or blacken the pla. You shouldn't get thicker strings. Those are more likely for larger nozzles (so stick with 0.4mm if you want to get rid of them) and they are more common if you are printing faster. For a really beautiful print I set all the speeds to 35mm/sec (infill, inner, outer walls, bottom, top speeds). But leave the travel speed as fast as possible. 300mm/sec travel speed is probably reasonable - I don't usually go that fast but it should help the stringing. If you go too fast then you will miss a step on the stepper and the whole part will shift on some layer. But 300mm/sec should be fine if you keep your rods oiled - just one drop only about once per month on the 6 rods in the gantry. Any light mineral oil is fine. 3-in-1 oil. Sewing machine oil. Any mineral oil. Even baby oil is probably okay. wd-40 is not great - it's meant for cleaning - not so much lubricating. Higher printing speeds means higher pressures in the nozzle. I wouldn't mess with retraction speed or distance but if you mess with the distance: The distance should be the right amount so that the filament is no longer pressurizing the nozzle but not enough to actually pull upwards and allow air into the nozzle. So if you look at the bowden at the top of the arc while it's doing the retractions you can see the filament come down and rest on the bottom of the inside of the tube - it's easier to see what I mean if you watch it happen. But if you look down where the filament enters the print head it should never move upward on a retraction. Check your bowden to make sure it is not loose - pull up on the bowden and it should not move up. Both at the head and the feeder. If it does then it wasn't inserted properly - remove the horse-shoe clip - push down on the outer collet and then push down on the bowden and then while pushing down pull up on the collet and then insert the clip. The bowden should not move up and down. If it does you can add that movement to the retraction distance. Did you mess with any other settings? Lots of things can make it string - I'd stick to the profile where possible. Lower temperature can also reduce stringing. Some print as cold as 180C. I use the default temps in the profile.

For people who don't want to do lots of copying of files, it would be better if you could save a project file. It doesn't need to have a model in it (no stl needed). Setup everything with the right machine settings, and the right profile, then do in menu "save" "project file..." and post that file which will contain the machine settings and profile settings. People can open that in any version of cura newer than the version in which you saved it.

Occasionally a newer version of the Mac is incompatible with older software. cura 4.8 is the newest that works with mac os 10.12 and older. At the bottom of this page is an explanation. Cura uses qt creator to make the same software run on windows/linux/mac and certain libraries all of which can have compatibility issues. Unfortunately. But it seems worse for the mac. https://support.makerbot.com/s/article/1667337917781 Regarding vase mode - the feature I think you are talking about is spiralize outer contour. Did you enable that feature in 3.6 and 4.8? Maybe you have it enabled in 3.6 but forgot and didn't know to enable it in 4.8? If you want to explain in more detail I guess you should post a screen shot in PREVIEW mode that shows an issue with one of the layers. That shows what you are talking about in 4.8 and in 3.6. Is the "continuous" issue when it changes layers? Sometimes cura jumps backwards when it goes up to the next layer which was very annoying. I know that bug was adressed eventually.

Found the problem!!! It's the bed temp. Okay so this is a bug... So you have the second core set to use ABS. Even though it looks to me like you didn't assign the second printcore to any part. And so there is a bug where instead of doing the normal buildplate temp of 60C it is choosing 85C. Which is too hot for PLA (any kind of PLA - that is too hot). So go back to the prepare tab, and disable the second printcore and reslice and you should be good. Although, damn, almost 2 days to print that! I don't have that kind of patience. I would do an AA 0.8 printcore and set layer height to maybe .3mm. .1mm is okay for small prints but this is pretty big. some people hate layer lines but I prefer them. Let's people know it was 3d printed. those two changes alone gets it down to 12 hours. I'd keep working on lowering that.

Is it doing it the same on all 4 corners?

Are you using a mac? If not then maybe you just need to update your video drivers and then cura 6.X may start to work for you. It's possible to have cura 4.8 and cura 6.1 installed at the same time.