Curling overhangs with PLA on SV06 ACE

[bcat]

Only negative I’ve noticed so far with the SV06 ACE’s print quality is that overhangs tend to curl up. I know a little curling is unavoidable (depending on the overhang angle), but the curl I’m seeing seems excessive, leads to messy-looking undersides of overhangs, and can even cause prints to be knocked off the bed (when printing parts with small bed contact area and no brim).

Any and all tips are welcome; in the meantime, I’ll write up what I can think of that might be relevant in case other folks are having similar issues.

Here’s an example of a print where I hit the issue (STL from here, though it’s a paid model, sorry). The print finished successfully, but with visible curling as it printed (that eventually got “squished flat” as the opposing overhangs merged together). Some problematic areas are circled:

I also tried printing this overhang test, but the print consistently fails in the 55–60 degree range. The curling gets excessive, the nozzle starts hitting the print, and the print eventually detaches. (I can retry in a bit with a brim to see how the print quality turns out when I take bed adhesion out of the equation.)

I read through this thread about a similar issue on the base SV06 model, but the solution recommended there doesn’t seem applicable to the ACE, which has an entirely different fan shroud. (FWIW, I did make sure the fan shroud is fully tightened, and angled as close to the nozzle as possible.)

I’m using PLA that’s been dried thoroughly and otherwise prints well. I haven’t changed any cooling or speed settings from the latest profile in OrcaSlicer Git, but for reference, slicer settings are as follows:

I also tried cranking the fan up a bit to a constant 90% + 100% on overhangs, but other than making the fan noticeably louder (it’s really whiny above about 80% / 10,000 RPM), there was no difference in printing.

I wonder if I’m just printing the walls too fast for the filament to adequately cool? I can retry the overhang test with lower wall speed and see how that goes.

[Lion]

I think I got your model pretty lined up with the file, I wanted to see what you were trying to print.

Also, what is your wall order set to…??

[bcat]

Sorry for the delayed response! (Things have been super busy here lately.)

My wall order is inner/outer (both to give overhangs more to adhere to, and because Z seams look like noticeable this way vs. with outer/inner).

I did manage to get that overhang test to finish by printing it with a brim. Overhangs look good great up till around 55 degrees, at which point the curling I mentioned before starts. By 65 degrees, the curling is excessive, and while the print stayed on the bed with the brim giving it extra adhesion, it’s sloppy enough I wouldn’t realistically print that steep an overhang unsupported. I’m having trouble getting a decent photo, but here’s some of what the completed test print looks like:

Maybe my expectations are just too high? I have certainly seen better-looking overhang performs in other people’s photos online, but maybe they’re running lower speeds and/or better, more custom cooling?

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P.S. I’ve mostly put my overhang explorations on hold because I got sidetracked by another setting visible in your screenshots: “Top surface flow ratio”. Notice that Sovol’s suggested profile (and the profile on OrcaSlicer GitHub that’s based on it) sets it to… 0.8. In my experience, that’s way too low. (For reference, most of the other Orca profiles have it in the 0.95-1.0 range, and none of them goes below 0.9 besides the ACE.)

That explains why I’ve been having so much trouble calibrating flow: the flow calibration test forces top-surface flow to 1.0, which makes sense, but then my top surfaces in actual prints were often noticably underextruded. I understand Sovol turning this setting down a little bit by default for cleaner top surfaces, but 0.8 is just not enough.

I’ve had good luck with top-surface flow of 1.0 and “Small area flow compensation enabled”. Those two things—plus well calibrated overall flow and pressure advance—give both properly extruded walls and smooth top surfaces.