Hi,
I received my H2D last week, and I’m pleased to report that it’s functioning superbly. The print quality is impressive, and aside from a single instance of a false positive air printing, I’ve encountered no issues. I did notice that the Y-axis bearing is quite loud with fast and long movements on the Y axis, but I think this is only apparent due to the otherwise very quiet operation of the printer, making the noise stand out more.
However, I am particularly surprised by the flow rate. I typically use Jayo PETG filament, and with my other printer equipped with a Phaetus Rapido 2 UHF Hotend—known for its excellent flow rate—I achieve a maximum flow rate of about 22-25mm³ for PETG.
On the H2D, I’ve set the flowrate to 40mm³, and the printer handles it well even when I switch to Sport/Ludicrous mode, pushing the flow rate to approximately 45-50mm³. Given that PETG is typically worse than PLA in terms of flow rate, these results are quite unexpected.
Does the H2D extruder motor have a mechanism to detect underextrusion and adjust the flow rate accordingly? Or is there perhaps another hidden limitation within the slicer/printer settings that caps the flow rate? If these flow rates are accurate, the H2D has probably one of the best hotends out there, making the HF version seem less necessary, especially considering the significant price difference between the standard and HF nozzles.
The profile speeds will be the limiting factor, not the flow rate past a certain point. Also depending on the item being printed, the printer might not have a chance to hit those speeds due to acceleration on smaller items. You can preview the speeds and flow rates in the slicer to see what its actually doing.
One of the big advantages of the HF nozzles is the better layer adhesion, thats the main reason I got them, stronger functional part strength.
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I know, but the infill is printed at close to 40mm3 according to the slicer without any problems.
Not sure if it the parts will be actually stronger with a HF hotend with the same flowrate. If the hotend manages to extrude the filament the strength should be equal, the temperature of the extruded plastic shouldnt be any different so the strength should be the same.
How well and evenly the filament is heated can indeed have a large effect on layer adhesion. The internal temperature of the filament drops significantly with faster flow rates weakening the layer adhesion. With a HF hot ends the filament is split in 3 and heated much more evenly at faster flow rates. Just because it can extrude it, does not mean the strength will be good. Do a max flow rate test in orca, and you will see the filament at the very top will pull apart much more easily by hand. Watch the video I linked for a scientific test of the concept.
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Better flows almost always equal better layer adhesion, provided some level of equality. Of course you can’t use the high flow nozzle at its limit and compare against the low rate nozzle at its limit and expect the same improvement. The test has to be normalized in some way. For example, both nozzles at the same rate, the high flow nozzle should win for adhesion. If it doesn’t, not sure its really a higher flowing nozzle.
The good news… I’m pretty sure someone will test it on You Tube after the review cycle is done.
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It’s conceivable that using a larger nozzle diameter might influence the outcome, however, with a 0.4 mm nozzle, I doubt that the temperature gradient from the filament’s surface to its core would differ significantly from that of a high-flow nozzle to affect the strength of the component. The outer surface of the extruded material must sufficiently melt the underlying layer to ensure strong bonding. With a 0.4 mm nozzle, the volume of material extruded is relatively small, meaning that its heat capacity is very small, thereby reducing the impact of any temperature gradient from the surface to the core of the extruded filament if there is any.
I believe that parts with higher strength produced by slower printing primarily benefit from the radiated heat of the hotend. This radiated heat preheats the underlying layer, allowing the filament from the new layer more time to melt into it, thereby creating a stronger bond. When printing at a slower pace, the nozzle/hotend spends more time preheating the layer beneath and the extruded filament. So a HF hotend wouldn’t make a difference in that regard.
Do the Bambu HF nozzles employ a filament-splitting mechanism like the CHT nozzles to increase flow, or do they utilize a different method to achieve enhanced flow rates?
My understanding is there is a special geometry on the HF nozzles, but I don’t think its a CHT design, but it may be similar.
Can’t find the picture I saw before.
It is indeed a CHT type design with filament path split in 3. And yes a 0.4mm HF nozzle will effect the layer adhesion and part strength especially at the high speed that the H2D prints. Even with lower flow/slower printing materials like PA, there will be a noticeable difference in layer adhesion, as the center of the filament will be heated up evenly. Again please watch the video for a good illustration of the concept backed up by scientific testing.
You can also read this, lots of data there including visualizations of different heating paths:
Also here is the bondtech white paper:
None of this is conjecture, you can not argue with data.
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I’m not disputing the higher flow rate of the nozzles; they certainly enable faster printing, which is clearly supported by your links. However, my contention lies with the claim that parts printed with a high-flow (HF) nozzle exhibit increased strength compared to those printed with a standard nozzle at the same volumetric flow rate. From a physical standpoint, this assertion doesn’t hold, especially for 0.4mm nozzles.
If a standard nozzle can effectively melt plastic at, for example, 20mm³/s, an HF nozzle won’t inherently improve the strength of the output, as the temperature of the extruded filament remains constant. The difference might only become apparent at the limits of the maximum volumetric flows, where a standard nozzle struggles with melting the filament efficiently, leading to underextrusion. However, to claim that HF nozzles invariably produce stronger parts is misleading and could potentially give a false sense of security.
The flow rate of the standard nozzle on the H2D for PETG is exceptionally high based on my tests, and I am truly impressed. I’ve never experienced any underextrusion issues even at around 50mm3 with standard Jayo PETG, which leads me to wonder if there is a built-in feature that prevents this. Considering that the extruder motor includes a built-in pressure sensor, it’s possible that this sensor is utilized to monitor the max flow.
The complete absence of VFAs is astonishing; every part emerges from this printer is absolutely flawless. .
I think that part is disputed.
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Even at 5mm³/s flow rate and 65mm/s print speed the HF has better adhesion, similar to running the standard hot end 20c hotter! It gets progressively worse from there, at 20mm³/s flow rate and 270mm/s print speed you are getting 3x the layer adhesion (10MPa vs 30MPa) as past 10mm³/s flow rate the adhesion falls off a cliff on the stock hot end.
Take at look at the visualization of heat transfer to different filament paths. It visualizes how a single filament path has a temperature delta between the center and outer edges.
I make parts that go into military vehicles and I need the best part strength, HF hot ends are worth every penny to me even though I print at regular speeds most days.
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The diagram clearly illustrates my point. At lower flow rates, the stock hotend operating at 240°C achieves best layer strength. Even at a flow rate of 15mm³, the performance of the stock hotend closely matches that of the HF nozzle. Additionally, the stock hotend demonstrates superior layer adhesion compared to the CHT clone. According to this diagram, the HF nozzle is ineffective for achieving maximum strength.
You managed to miss the point completely. CHT clone is just that a bad copy approximating a proper CHT hot end with inferior design and materials, its not comparable to Obxidian or Bambu HF. If you want to print at 240c at 15mm³/s and 200mm/s you dont need a HF hot end you are right. At 260c the layer adhesion will be even better, but we dont print at those temps for a reason. I did not buy my H2D to print slow and with subpar quality but to each their own.
Depends on what part of the diagram you look at.
You’re correct for low flow rates, but the differences are minimal, whereas at high flow rates the high flow hot ends are much stronger.
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Yes the flow rate differences down low are margin of error, so pretty much identical. 240c adhesion was tested for illustration purposes to show the contrast of how efficient the CHT is, comparable to printing 20c higher with stock hot end. You can print at 240c but only at higher speeds so the filament does not have time to overheat with fast extrusion. That temp is too hot and quality will suffer if you print at 240c at slower speeds. But you see what you look for as Noah mentioned.
I’ve seen that video a few times as I understood it on my P1S if I want a pla part to be stronger I can print it at 240 instead of 220 right? Which would be equal to running a quality high flow nozzle.
240 is not a good print temperature for PLA as its too hot, unless you printing something big and really fast so it has no time to overheat in the nozzle. Even then its not really a viable replacement for a proper HF hot end, and will cause uneven heating of filament with a temperature delta between the outside and inside the extruded filament.
240c was mainly added to show that a HF hot end is as good as running standard flow stock nozzle 20c hotter, it was not to suggested to print PLA at 240c.
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Can the profile speeds be adjusted?? because I somehow managed to get it to print Polylite PETG at 476mm/s close to to a 50mm/s3 Flowrate. However now that I try it on other parts it caps at 350mm/s. Why??? Here is the test that I modified for the H2D from X1C. Bambu slicer max flow test tower for X1C by keenzkustoms | Download free STL model | Printables.com
Here is my modified version:
PETG - Volumetric Flow Test_H2D.3mf (52.6 KB)
Certainly, you can adjust the speeds in the profile and just save it as a new profile. A volumetric flow rate of 50mm³ is insanely high for PETG, which typically has a much lower flow rate compared to PLA i.e. I’m not sure if there’s another hotend on the market that can achieve these flow rates for PETG at the moment. I’m still a bit skeptical about the accuracy of the flow rates specified in the slicer but estimated print times have been really accurate so far. I’m gonna try out some HF PETG and see if I can achieve an even higher flow rate 
It doesn’t seem to be working for me. Here is a .3mf file of something I slapped together to test. The fastest I can achieve is 300mm/s which would be just shy of 30mm3/s Volumetric Flow? If you find a way to beat that it would make my day. And yes, 50mm3/s is crazy but the print quality was still very nice w/PETG 
Cylinder_Speed_Test.3mf (40.1 KB)
