Yesterday I received the H2D, and the first thing I did was set up and fine-tune the profiles for the filaments I use regularly to ensure optimal print quality.
I started with Overture ABS, which is my most frequently used filament. I first ran the automatic K-factor (pressure advance) calibration, followed by a manual flow calibration.
What stood out to me were the K-factor values I obtained—ranging between 0.036 and 0.040—for Overture ABS. This is notable because on my P1S I typically run the same filament with a K-factor of 0.024.
Is it expected to see higher K-values on the H2D?
Could the difference in extruder design be influencing this?
Doesn’t the H2D run an auto flow calibration before every print? I didn’t need to tune my overture non-crf PA at all, and I have heard it’s kind of a pain to print with.
Yes, you can choose to do it or not, but I find it interesting that when you calibrate a material manually, you get a value close to 0.020, whereas with automatic calibration, it ends up closer to 0.040
The eddy sensor approach that A1/H2D uses for this is just a ballpark, serviceable, but will not produce results as sharp as visually inspected full manual ‘pattern’ calibration. I never use it except for materials I don’t use often enough to justify manual fine tuning. Nothing beats manual, it’s consistent and way less poop buildup.
Getting a slightly lower manual K matches my experiences. The servo motor supposedly has a sharper response than past stepper motors so less need to ‘compensate’.
You should also calibrate it separately for both nozzles as the Left one has a longer gear→nozzle filament path. And separately if you ever get a HF nozzle.
No, that’s only applicable for Lidar. This time with the eddy current sensor it’s quite different. And actually you get a huge lot different result from it, e.g., manual K value result is 0.02 and automatic might be 0.033
I got the same result as OP, interesting. My manual pattern based eyeball result is 0.02s, while the automatic calibration constantly gives me 0.033s. This is a quite large variance. But the result is consistent in both left and right nozzles. I’m using HF 0.4 nozzle.
here is my result using bambu pla basic. 0.02-0.024 is pretty good to me (the angle looks quite straight). The automatic value of 0.033 would have under extrusion.
Let’s be clear that what I said is ‘serviceable’, that manual K is sharper. What one would consider things to be ‘flawless’ is a semantic question and one I have no interest in. I’m not telling anyone else how to use their machine, that’s their own decision.
All I was saying was stating an observation across dozens of common and engineering filaments, on two A1, one H2D, 0.2/0.4/0.6, across thousands of print hours, via both test objects and actual complex inorganic prints, between Auto and Manual K, with manual flow rate tuning. The consistency of such observation suggests it to be a fact.
With all due respects, you stated that you only did auto Ks. I’m not sure what you have to challenge me, and this is not a place for Twitter duel. The testings I did arriving at this conclusion adds up to a few work days so unfortunately due to this hassle, I’m not going to sit here reprint everything side by side just to show you. What anyone else makes of it is up to them. Frankly I get nothing out of this so I’m not sure what’s my incentive to make things up. The manual tuning option is there in the studio and methods are readily available for anyone curious.
The article didn’t really specify that problem being for just Lidar. Regardless, I did observe variances when doing auto Ks on PETG-HF back to back, thought that was curious, and moved on to manual.
HF0.4 is a curious one, tho intended for high speed, I wanted to see whether it provides any benefit for quality focused slow printing from “better melt zones”. It did fine for PC, but PETG-HF struggled to produce edges on par with default hardened 0.4 even under 0.002 value step. It was all either over or under extruded.
In terms of the variation between Left/Right, it’s possible the difference is not big enough to show up for some combinations. It was more pronounced with the 0.2 nozzle which I got a 0.008 difference in-between.
I looked up K-Factor, and everything I got back was Sheet Metal. Then I looked up “K-Factor 3D Printing,” and all I got was pages where they talk about K-factor with none of them defining it. I got frustrated, and asked Brave Browesr’s built in chatbot, Leo. Leo gave me a straight answer, that took about as long as this post is. Thanks for making for me work for it —I forget we have this thing called computers that can define stuff for us.
In fact, only Bambu Lab refers to it as ‘Factor K’; in the context of 3D printing, the correct term has always been ‘pressure advance,’ as I previously mentioned.
Right, but it’s slightly different. In general consensus PA values are usually considered to be a linear parameter. While Bambu seem to have applied an algorithm to somewhat make it can adapt a bit. It’s somewhat close to “dynamic PA” but instead of doing it by manual measurement, it’s doing it via a pre-trained algorithm, which is why they can claim they improved the extrusion accuracy and blah blah by upgrade firmwares.
Thanks for making for me work for it 
—I forget we have this thing called computers that can define stuff for us.
