Unfortunately, I had to realize today that I’m part of the club as well. I’ve opened a ticket. The prints looked good at first, but with this print, I was able to notice the issue too. The entire surface should be completely smooth here.
It is the exact same thing I see on my H2D.
Something triggered by the structural change persists for the whole layer even over multiple objects.
But what is it that has changed? Extrusion, filament temperature, cooling aka fans, z-height?
Some tests I could think of that might shed some light into this:
Whole plate filled with cubes. First (in print order) has small holes to trigger the structural changes.
How many cubes show the layer lines? Does it slowly fade or not?
If it doesn‘t fade, is the first layer above the hole free of the defect for all cubes?
Then the effect persists until a layer change and is related to the z-height (maybe z-binding).
Edit: Just looked closer at your picture and it seems to fade.
If it does fade, it is not z-height related. To further investigate what has changed, the cube printed second after the one with the holes could be sliced with modified values for print speed, fan speed or extrusion (altered individually one by one).
Idea is to find the modified value that produces the least layer lines by compensating the wrongly changed value triggered by the hole.
F.e. if the extrusion is higher after printing the hole because of the retraction/unretraction, a cube sliced with a lower flow rate would compensate for that overextension and should look better.
Ideally you do this only in the height range where the holes are. IMO height range modifiers are broken in BambuSlicer. Then you can only check the cubes afterwards (3 and following) and hope the change back to the initial values do not produce new artifacts.
Btw. I’ve sent Bambu support a ticket including pictures and gcode about the issue.
Answer was:
Based on the information provided, I highly suspect that this issue is due to the layer time difference. This issue arises when the printing time for a particular layer in the model significantly exceeds that of its neighboring layers. The extended printing duration leads to a notable increase in the cooling time for this layer compared to the surrounding layers. Consequently, this prolonged cooling process results in the layer time discrepancy line.
In this case, we recommend trying the following steps to see if there is any progress:
- Reduce the wall speed to 60mm/s
- change the order of the wall to outer/inner
- Reduce the speed of the AUX fan to 40%.
While it contains some suggestions already posted here I don‘t think this will be the final fix for the problem.
Outer/Inner doesn’t work well for models with overhangs and having to slow down print speed for everything other than smooth round objects cannot be the solution for a $3000 printer.
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I don’t think it is software i just printed a tall piece petg with different speeds in it. No z banding whatsoever
I also don‘t think it is solely software (slicer) based. But I don’t think it has to do with loose screws or belts either. These would generate random artifacts and not ones that are aligned with structural changes in the model.
I suspect it is something with the new extruder in combination with the eddy sensor. Bambu said the servo motor in the extruder can measure torque and in combination with the eddy sensor in the nozzle can dynamically change flowrate as needed while printing. Maybe the system overshoots occasionally in its effort after a structural change in the model and not dials back to the exact flow rate it was before the structural change.
It this is true it would be firmware related and nothing we could fix ourselves.
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Various filaments behave differently.
PLA sparse infill patterns can also affect outer walls, sometimes causing visible strip lines especially noticeable when reviewing layer time look at cross hatch shows strip lines vs rectillinear no strip lines. These strips will show up on the parts outer walls even with 3 wall loops.
The Z band offsets appear to occur based on the part’s design, the type of filament used, layer time, and the duration the filament spends in the hot end’s thermal melt zone. As the plastic filament becomes more liquefied, extrusion errors are more likely to happen.
Bambu has said at this time, the printer does not change values on the fly, during printing. It uses the calibrated values from the beginning of the print.
I really hope Bambu finds a solution soon.
Hi everyone,
I just got a new H2D and I’m experiencing the same issue many others have mentioned — visible Z-banding on every single print.
So far I’ve tried:
- Updating to the latest firmware
- Recalibrating everything
- Moving the printer to a more stable location (floor)
- Tightening all screws and checking for loose components
None of it has made a difference.
Even the default Benchy included with the printer shows clear Z-banding.
I also tested with a basic calibration cube [makerworld .com model 14695] — same issue.
Unfortunately, I can’t upload images here, but the artifacts are very noticeable.
I’ve already opened a support ticket, but posting here in case anyone has suggestions or has managed to resolve it.
If even the benchy shows clear banding there is something wrong.
You should open a ticket with bambu support.
Has anyone picked a test model, chosen a filament, and created a 3mf that we can all print?
Shall we do Bambu pla basic gray? Maybe Bambu PETG-HF gray?
Let’s pick one and get some comparisons going.
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I only see some banding on PLA due to differing layer times/volumetric speeds leading to uneven expansion of the plastic. Other materials like ABS are flawless and have 0 layer lines.
Is this a machine error or a slicer issue?
I’m asking because when I added text to the side of a model—even when keeping it perfectly flush with the surface—I ended up with strange layering artifacts specifically where the text was printed. It appears as if an extra micron-thin layer was added to the wall, creating a visible 1 cm band around the model. This doesn’t happen on my X1 Carbon—only on the H2D. Without the text, there’s no band at all. That makes me suspect the issue lies in the slicer, not the machine.
I also believe it’s a slicer issue. We can confirm that if we all get the same exact defects if we all print the same 3mf with the same filament. If all our prints come out looking alike, then it’s the slicer. If all our prints look different, then it’s the machines. In theory of course.
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I noticed that the default Bambu profile use the classic slicer. IMO Arachne solve a lot of these banding issue related to steps in the geometry, as it spread the layers out in a much more dynamic way.
Luckily in my case, and unfortunately for this thread, my H2D arrived printing well out of the box, but I also switched the slicing method to Arachne fairly early, so there could be a correlation. For those still struggling to find a solution, maybe that’s worth investigating?
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I would also be very interested in this experiment. I have a lot of different filaments here to test. (PLA Basic and PETG HF in grey for example)
My H2D prints well, but I’m also interested in us picking a model (even a single 3mf file) that we can all just click slice & print on to see what happens. Any ideas for the model?
I don’t have any basic PLA but I do have PETG-HF, PLA Matte and PLA-CF.
Just wanted to throw this out there. I got curious today and decided to see what the inside of the extruder looked like. I found these 2 screws were loose. Not by a super lot, but about 2 full turns. I tightened them up and checked all the other screws along the way, including the ones on the back side of the hot end heaters. Everything else was good.
If both were loose perhaps that’s intentional? To allow enough play for the nozzles to switch
That did cross my mind, but I went over the assembly wiki and they say to fully tighten them.
*Edited
I found a model on Makerworld we could use for our test:
It only uses about 20g of filament and the print time is also very short. What do you think?
Do we want to print the same .3mf file or the same .gcode file?
The last one also eliminates the influence of the slicer.
Looking at the 3mf file after slicing, this model should have some visible banding. Layer speed illustration:
I’ll print it anyway.