Struggling with ASA & possibly a Studio bug

[orbitalr]

Hi all.

Only a 100 or so hours on the Bambu H2D, no other Bambu printers in the past and not used ASA before but have recently been using PA6 very successfully. I used a modified Cartesian printer for a log time running Klipper so generally appreciate most print issues.

This one has me stumped.

TLDR:

ASA print is inconsistent. Some walls have (heat) overhang issues while other walls of the same profile are perfect.

Cooling settings changes in Studio don’t seem to work as expected.

esun ASA, new roll. Temp range 250-280. Not dried from the packet but its sitting in the AMS which is holding 9% so not expecting to to be moisture. However, I’‘m drying it right now.

H2D, .6mm standard flow nozzle. Engineering plate.

Print settings are pretty much a copy of Bambu ASA settings with:

Volumetric flow reduced to 10mm3/s

First layer @ 275, other at 255, bed @ 100, chamber at 65.

Flow ratio and K calibrated.

All calibrations recently run on the printer.

This the object.

The long side is perfect:

The shorter sides are not:

Ive tried tons of combinations on a small part of this object. Admittedly the small part is creating additional problems because the layer time is so short but the symptoms are consistent as an exaggeration of the above:

I can consistently print this object with the 10ish layers looking acceptable. Between 10-43 its uncontrollable. Its always clumpy on that left side. Those small blobs always appear in a similar position towards the right, at best less than half as shown above. On the bigger part these only appear in the last few mm of a layer at specific points.

I dropped the temp down to 250 and this seems to have helped in the first 10 layers.

Ive tried varying amounts of cooling from 0-60%, this seems to make very little difference.

Tried reducing the chamber temp to 60 but this seemed to encourage the part to lose adhesion and didnt seem to help. I could switch to the PEI plate…

Ive reduced the minimum speed to 15mm/s but struggling to get the middle part to print slowly. This is where i think there might be a software bug.

Regarding the wall speed settings, I cant seem to control them other than by adjusting the layer time. Even with these aggressive settings the middle section is printing at 150-170 mm/s. The layer time there is about 2.3s.

If set “Overhang Threshold for Participating Cooling” to 100% (or 0%) , same speeds as above.

“Cooling overhang threshold” makes no difference to print speed. It does change fan speed, as I’d expect. Oddly, it seems to change the fan speed for the entire layer, not just the overhanging line.

Back to speed, if i enable “Dont slow down for outer walls”, it still seems to slow down those early (pinkish) lines which it will print at about 50mm/s. Again, “Overhang Threshold for Participating Cooling” makes no difference to this. For reference the layer time there is about 7 seconds.

I cant get these 2 second layers to slow down no matter what settings I change, they don’t trigger as overhanging at this point.

What do i want to achieve?

There are parts of the bigger print that are equally as good as PLA but it’s inconsistent in places and I want that consistency.

I’m not able to troubleshoot it because I dont think the slicer is doing what I’d expect it to.

Thoughts? Do you think it’s just the nature of this brand of ASA?

Thanks!

Mike.

[Bullocks]

I don’t have much to add other than that if you want to slow down your layer time further for more experimentation, put two of them on the bed to print.

Hard to tell in the pics, but is it staying adhered fully to the bed? Pic 3 looks like it might have lifted the corner and started the cascade of bad.

[RocketSled]

Bad filament. Do you have another roll of ASA to try?

[MaxThreeD]

Funny, I was just reading an opinion elsewhere that with ASA especially “you get what you pay for” and the person even called out eSun specifically. I have no idea, but I’ve had good luck with Bambu ASA for far. Absolutely dried it first.

Regarding the layer speed, have you tried adjusting speeds in the “Speed” tab of the print settings? That seems most direct…? I’m not discounting cooling, but that seems like backing in to the speed settings.

In filament cooling settings, the fan pre-start time can add to overall layer cooling, especially on quicker layers. In some cases the whole layer might be cooled just because one spot has a little overhang.

For smoother corners and other transitions I’ve taken to lowering the Quality → Advanced → Smooth Coefficient setting to 1 or below (and making sure Smooth speed discontinuity area is checked).

Cheers,
-Max

[RocketSled]

None of that should be necessary. I just loaded a bunch of ASA (Inland brand purchased at MicroCenter) in my printer, that’s been sitting in a storage bin in my basement for well over a year. Printed great on the default “generic ASA” profile. AMS says 27%. Literally no adjustments to anything. Slice ‘n Print.

[Twitko]

I didn’t notice (sorry if I missed it in your post) what speeds you have set for printing in the SPEED tab. I am by no means an expert on ASA printing, but I have printed a little (and quite successfully). And when I was researching “How to print” before my first ASA attempt, I found a lot of recommendations for low speeds, like this one:

e.g.: SLOW - first layer lower than 50mm/s (others recommend 30mm/s) … other lower than 140 .. These are maximum speeds, I usually reduce all numbers above 100 to 100mm/s

I try to stick to this and it seems to work… However, I repeat, I make all these settings primarily through the SPEED tab… I consider the others, such as volumetric and cooling, to be more like “fine tuning.”

Forgot to mention: I have P1S so some details may be different, but I believe the basic is the same

[orbitalr]

It was curling a bit there. That corner doesnt have a large footprint. The opposite side wasnt lifting and also has similar defects.

Good idea on how to increase layer time by other means though.

[orbitalr]

Have you got a link to the thread? Interested to take a look. I agree and have noted with a friend who uses FDM printers 10x more expensive that they require you to use their filament. There’s certainly benefits in printing with Bambu’s material as they offer “off the shelf” profiles which just work (they’re designed to!).

Thanks for bring up Smooth Coeficcient, I did wonder about what that setting did and hadn’t gotten around to reading up.

[orbitalr]

Speed, I didn’t say, that wasnt intentional. That print prifile is configured to 10mm3/s on volumetric flow rate. Based on the other variables, I believe that works out at about 90mm/s.

I had a search though before posting and noticed a few cases where poeple say their P-series printed the same object perfectly where the H-series didnt. When reasearching before buying some of the YouTubers would critique something followed by “will hopefully get addressed in a future update”. I appreciate some differences may exist.

[orbitalr]

I have been configuring pressure advance and flow manually, the K value generally to 0.001. Thinking about it, maybe I should put more faith in Auto Flow Dynamics Calibration.

So I’ll think I’ll re-enable that and have another go. Its supposed to be good:

Community Tech Talk: Deep Dive into Auto Flow Dynamics Calibration

Auto Flow Dynamics Calibration is a signature feature of Bambu Lab printers. This system calibrates both the filament and printer conditions to establish precise parameters for Pressure Advance—a critical factor in maintaining consistent extrusion during the rapid speed transitions inherent in high-speed printing. As we continue to refine our algorithms and improve the user experience, we are seeking detailed feedback from the community. We want to know how this feature is performing in your sp…

[user_2463535618]

I didnt see your room conditions so I apologize if I overlooked it. Even with a heated chamber is it possible your printer is in a location with a sudden/planned/casual drop in temperature that could be causing any of this? If it drops a few degrees celsius in the room, I notice results change even with the printer doing its thing to keep it nice and toasty inside. I have 1 minute resolution on environment sensors where the printer is and when something like this happens it usually happens when the temperature drops in the room.

[orbitalr]

Hi, small room, heated and insulated. Sits at about 23C when occupied or printing.

[orbitalr]

I’ve made some progress, got to what i think is a reliable stage.

I found that fan speed in heated chambers can be aggressive without having a major impact on the part, I expect because it’s pretty warm air thats being circulated. At one point I was accidentally printing at 85% fan and didnt notice.

The mot reliable way to control speed on short duration layers was by extending the “max fan speed threshold” - “layer time” value. Really long values.

Ive got this somewhere near where a small part can print to an acceptable quality eg 30x50mm with 2.5-3mm walls, 0.18mm layers, .6mm nozzle (below).

The biggest impact was getting the print speed down to allow the layers to cool slowly. Most of this part was running at 20mm/s.

Smooth coefficient didnt demonstrate any difference in the slicer preview, possibly because the speeds were already quite low(?)

I tried different combinations of a lot temperature things (except nozzle). Dropping the bed temp and chamber temp did help with wall quality but warping challenges occurred and part fan needed to be very gentle.

In the end, adding a little more heat to the bed (105 from 100), dropping the chamber temp (62 from 65) and running the fan between 10-35% seems to be consistent.

I ran with auto flow dynamics, I’m going to keep it on.

Looking at the part, I could probably drop the bed temp down a little but it didnt warp. I used a 3mm brim.

I agree the part could be better, the edges show some signs of plasticity but I’m rarely going to print something like this in ASA. I dont think the bigger part will be a problem now.

Cheers for the tips everyone.

[orbitalr]

Following up, when I printed the whole part the defect re-appeared. I assume because the layer time increased it sped up.

Ive printed another part with different material recently and something similar happened. Larger overhang was fine, as the overhang reduced defects started occurring.

Some of these overhangs are at 100% fan and about 45mm/s. They’re not aggressive overhangs.

Could probably tune it out with the overhang speed settings but they aren’t applied to the sliced model.

[RocketSled]

Rotate the part 90º around Z so the printhead will be running “orthogonally” to its direction when printing this area. See if that effects the defects. Does it stay the same? There’s something about what the slicer is deciding to do that’s causing the issue. Does it change? We’re looking at a physical contribution like the XY mechanics repeatability in this area, or a weird temperature issue (like a hot spot inside the printer).

[orbitalr]

I can give it a go. That print was done with that face towards the door. Ive tried that component in multiple orientations.

This (below) is PETG-CF. As you see it, the sphere was pointing to the back of the printer. That defect stops at about the centerline, there are no issues on the other side.

I raised a case with support, they’ve said its likely to be overcooled and causing shrinkage. I’m not entirely sure thats the case. Certainly with the ASA print I’d tried almost every combination and the un-cooled prints were shocking. It did seem to make sense to me that in a heated chamber the air that’s moving around is warm and not quite the same as un-heated.

They provided a project file with some modifications which are severely reducing speeds… to the point where I could have spent a lot less money (and time) to achieve the same performance. That print above in PETG-CF has a max vol. flow of 7 mm3/s. By my reckoning, thats not fast, unless its not honored.

Generally a bit disappointing.

[RocketSled]

For something that’s all overhang, this isn’t really that bad. What are you using for support material and support interface settings?

But it does show what I think is a cooling issue. Assuming there’s nothing else at the same Z height in this model that has a much longer extrusion time, the blobbies are almost certainly cooling. Not not too much, not enough. When the layer time gets really short, the extruded plastic doesn’t cool down enough before the nozzle comes around on the next layer, the not-cooled-enough plastic flows as the new layer is being pushing in to it, and you get the little splooged out blobs.

[orbitalr]

@RocketSled

For something that’s all overhang, this isn’t really that bad.

That’s whats really agitating me, the significant overhangs print really well. Its as the overhang reduces and the print speeds up that it goes to poop.

That previous one was PLA+ support and intrface with 0s on interface distance and 0 on interfacing. Tree (auto) “strong” I think.

Ive just done the project Bambu sent over, still not good despite the low speeds:

(That support was the 0.18 Balanced Quality default process with single material and its equally as good).

Just going to try a Benchy with default/generic profiles (with conservative volumetric speed) and see how those fare.

[Steve_KA5YFC]

I run my bed at 110C. It seems to work better than 105C.

[orbitalr]

Cheap PETG - OK
ASA - OK ( a little elephants foot)
PETG-CF -

Those were generic profiles. Think I’ll try more aggressive cooling with the PETG-CF.

Still think tuning it out on the overhang speeds would be the answer. But as you can see, that ain’t doing jack (compared to orca, off/on(default)/on@10mm/s: