I have done som printing for months with no problem but lately I have been doing bigger prints with many flat surfaces and starting to experience quality issues…
The surfaces just look stringed or the lines is so very visible and feels like its to low temp or to tight with the nozzle… its not smooth at all. I have done the calibration needed and even looking to do Flow Dynamics and Flow Rate even if they are done automatic on H2D… Any help on what way to go on this appreciated. I have also dried it to a 10% level or below. I use only PLA Basic and also on PETG-HF from Bambu Lab.
You’ve already done a lot of the right things — drying to below 10% RH, running the basic calibrations, and using Bambu Lab’s own PLA Basic and PETG-HF. So here’s what I would look at next, based on your description and the kind of surface artifacts shown:
1. Lower acceleration and outer wall speed for large flat surfaces
The H2D is fast, but its default speeds can introduce artifacts on wide, open areas. Start by reducing Wall Acceleration to 500–800 mm/s² and Outer Wall Speed to 30–50 mm/s. This alone often makes a big difference in surface smoothness.
2. Don’t trust the automatic flow calibration blindly
Yes, the H2D performs automatic flow calibration — but the factory result isn’t always optimal for every spool. If you’re seeing uneven surfaces or slight ridges, re-running Dynamic Flow Calibration (Pass 1 and Pass 2) manually is absolutely worth it.
3. Watch out for slight overextrusion
PLA Basic can sometimes slightly overextrude, especially on large top layers. If your surface looks overly “textured” or ridged, try lowering the global flow rate by 2–3% temporarily to see if it improves. Then fine-tune via calibration.
4. Ironing can cause roughness if not dialed in
If you have ironing enabled, try disabling it for now — especially on large areas. It can sometimes make the surface worse, not better, particularly if flow is even slightly off.
5. Check nozzle pressure on first layer
Your comment about it feeling “too tight with the nozzle” might indicate your first layer is slightly over-squished. Run a fresh first layer calibration to make sure the Z offset isn’t pressing too hard — that can ripple up through the rest of the print layers.
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Thank you for a really good feedback. I have tested some of your suggestion but it didn’t give any specific great results. Just the overall difference on the same plate also gives me the headache on what exactly is going on. Would it be better to really start over with fabric settings, do the calibration again and do a print test - based on that do the flow rate or first layer test?
I think that would be the best option for now—reset the filament settings and run a full Dynamic Flow Calibration, both Pass 1 and Pass 2. Then calibrate Pressure Advance, perform a first layer test, and run a temperature tower just to cover all bases.
Also, going forward, make sure the build plate is clean. Avoid touching it with bare hands to prevent leaving fingerprints or oils that could affect adhesion or surface quality.
You wouldn’t happen to have the vision encoder for the H2D do you? I assume not as you would have mentioned it.
It’s hard to say if the printer is producing worse prints or you are just printing objects that expose some defects you’ve always had?
How do you know you have dried the filament to 10% RH?
Yikes, let’s not open the RH debate again—we could go on for months and still end up exactly where we started. 
Relative Humidity is heavily temperature-dependent and doesn’t actually tell you how much water is in the chamber. It only reflects how saturated the air is at that specific temperature. So if you dry your filament down to, say, 10% RH at 65 °C, and then let it cool to room temperature with any residual moisture present, the RH will spike—despite no new water entering the system.
I’ve said it before: absolute humidity is a much better indicator of actual moisture content in the chamber. But this is one of those eternal topics—some swear by RH, others swear by AH, and neither side is going to budge anytime soon.
Personally, I’d love to see Bambu Lab display AH instead of RH across all their devices. It would save us all a lot of interpretive gymnastics. 
I was just saying that drying the filament and reading the hygrometer might not tell the full story?
I can see that when I dry filament and place it in a cereal box with a hygrometer and desiccant the humidity stays at around 10%, but is that an accurate measure of the filament? Maybe it is.
I assume when folks are saying their filament is 10% or lower humidity, they are reading the meter in something like a cereal box.
Turn off reduce retraction on infill
After more tests I can say it was a mix of things… First off I learned there is some screws under the base for the plate that can be removed that can impact artefacts close to the window - and that I had on some of the test - removing them doing new calibration made that part go away - but still not good result overall.
I had the new 0.4 High Flow nozzles and when I switched left and right nozzles I got the result expected… it seems it was the new nozzles all along. Trying check if there is something wrong or filament inside - but it’s clean but just gives bad quality and uneven results. The calibration showed the settings I had was the right one but yet it got bad results. I have done a couple of more prints after with the “left” nozzle that was good but I got same results with it just after 3-4 runs… Im not sure if its something wrong from the beginning with them or if my new filament is the issue - but I went back to my normal 0.4 and now done 12 prints with no issue at all - even the ironing works really great. First layer look good as well now.
Anyone having problems with the new 0.4 High Flow nozzles?
I just wanted to loop back of the issues I have experienced and also a big thank you for the help to the topics that learned me a lot on the road.
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Hi there! I just have this problem but with the normal nozzle! Is the exact same issue!!! You just swap the nozzle and start working fine?
I started using my H2D when I first got it with the highflow nozzles and always always always got prints that looked like your pics, the tell tale buried cross lines visible, really irked me. I did every calibration and nothing made it better, I literally sadly just gave up using it for anything that wasn’t huge, and knew what to expect. Then both nozzles clogged, nearly simultaneously, I swapped them for non high flow and it got DRAMATICALLY better, like a LOT better. Before I had top surfaces so bad I had to sand them so they could lay flat, now it’s still pretty bad but not AS bad. This is very disappointing as I’ve got 7 Bambu Lab printers, and the H2D is my least used because of this. It also turns out that the high flow nozzles did NOTHING without manually tuning speeds and differently calibrating based on artificially speeding up prints, it was too complicated to worry about for every job so I just gave up on high flow entirely.
I print items to sell, so this is my livelihood, and I’m having similar issues with the P2S, which coincidentally but unfortunately, also cannot get good ironing results lsame as the H2D.
I have to use my X1Cs which reliably reproduce duplicable results for the past 3 years.
I’m not sad that I bought the H2D, but I’m very disappointed in its print quality. I’ve never gotten a good top surface and never gotten a good ironing result. I have just given up trying at this point, nothing seems to work to improve it. I’ve honestly just hoped Bambu puts out a firmware update that fixes it someday.
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