i was waiting to buy the printer not in the first wave bc problems of this and ■■■■ i feel a bit bad bc of this
Im gonna tag him again in hopes he might appear.
@SupportAssistant we need input here… This does not look good.
Check now after the current task finished.
Now I have fibers ON the belts and already after 8 hours print, the damage is bigger.
Moreover, I checked again with the movement check. My belts drift up and down A WHOLE MILIMETER , and the belts appear to be BENT sideways. Like , not in the direction they bend anyway due to the rollers, but literally bent down/upwards. Ill try to catch that in a video but its difficult with 2 hands only…
Fibers already dropping and sticking out
Deviation on Right gantry roller, one with toolhead all the way left, one with the toolhead all the way right.
Deviation on the left roller, likewise
in the first photo you can even see the teeth on top starting to curl/round up.
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If anyone is curious about what Bambu support said to me in regards to this issue.
Below is the text copy pasted, spelling errors included lol.
Hello
Thank you for contacting Bambu Lab support.
I am the technical support agent assisting you with this matter.
Wear-resistant nylon cloth in the process of immersion dyeing, ussing glue filling and dyeing black, after curing, there will be a layer of black thin substance on the surface of thecloth.
After the tooth surface engages with the driving wheel, the black material is peeled off, causing the belt toproduce similar scratch marks, and part of it will fall on the housing.
This phenomenon will not affect the belt life and printing.
Please rest assured to use.
If you want, you can remove the black debris, which will gradually decrease until the side walls are completely clear.
After that, no more debris will accumulate.
I hope my answer will help you with the problem you are experiencing.
Please let me know if you have other questions or if I can assist you with anything else.
We are here to help you!
Bambu Lab Customer Support
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These belts are very strong structurally but the black coating on the back/edges isn’t particularly abrasion resistant.
I agree it would be better if the belts ride in the middle.
In my case mine don’t rise or fall - but just ride at the top of one pully on one side and bottom on the other.
My Prusa Core ONE which I have verified square and coplanar with the bed which is coplanar with the frame - my belts ride higher on one side than the other.
I don’t (yet) have wear material coming off the belts of either.
I’ve only had them a month but I’m doing ~20 hours per day printing so they don’t have a ton of errors.
I’ll have to check the gantry on the H2D but I suspect that it’s not something I can adjust.
As far as voiding your warranty, at least where I am, they have to be able to prove any modification you make directly caused whatever failure to be able to refuse coverage for the issue.
Now if you take it apart and break something - warranty won’t cover that. If you take it apart and find something already broken that would be a warranty issue for sure.
If you take it apart and put it back together completely and correctly - that wouldn’t affect your warranty here.
Time will tell if it’s a real issue or purely cosmetic as they imply.
This is correct. There is no need to worry for the belt sides changing color.
The printer and belts have been tested extensively.
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It’s not about changing color please don’t overlook half the issue statement. It’s not just that a tiny amount of color is lost, it’s that there are obvious alignment issues! Please don’t act like it’s not serious if your belt derails itself. There’s signs that the gantry or the belt anchor points are not aligned. Even if it’s not affecting the print quality, I’ve never seen any company claim that a belt that is not running is normal 
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How rigid is your H2D? Does the belt change its travel path /how high it rides on the roller if some twisting force is applied to the housing? Maybe the loose screws issues also sneaked in to the gantry assembly…
Its rigid. The issue appears to come either from a twisted X rail OR baddly possitions belt anchors. To put it simply, the belts appear attached HIGHER on the toolhead, than the rest of the path/rollers etc, so when the toolhead approaches either corner the belts tend to follow the attached height, leading to them grinding on the lip.
(Note please ignore any downvotes/comments from 3 specific members, they appear to follow me around and just troll whenever I post, even when its obvious they know nothing on the matter and have admitted so themselves. Their behaviour is suspicious as they seem to roam the forum and attribute all issues to user error/missunderstanding, when its clear with proof that this is not the case. Im starting to think they are paid to aleviate the amount of bad things said in the forums, other wise i cant explain how its always these three guys diminishing anything regarding an issue as user error)
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You aren’t going to find a single core xy that remains perfectly aligned through an entire belt path. Even the smallest angle, aka any angle, on any pulley will cause the belt to ride up or down along the path. This is also true for the height.
Now, if you were having binding issues, by all means contact support as that is an issue beyond the belt path as something else would need to be quite out of alignment.
You are making a bit of a mound out of a mole hole here. The outer edge of the belt is going to lose its rubber coating with any amount of contact with the pulley edges. It does NOT effect the longevity of the belt. The constant pulling and strain from the toolhead moving is what will cause the belt to wear out, a long with the teeth slowly getting misshapen.
To make this more evident, have you ever replaced a serpentine belt before? The sides of those get worn just the same and is never the failure point, it is the stretch that slowly kills them.
Now, if you start seeing the fibers build up (and no, not just 1 random 1" long fiber you randomly see) or the actual belt fraying, then yeah, you’ll have a case.
I dont know where you get your info but you are wrong. Ive never had a single CoreXY with allignment issues like this and ive gone through about 40-45 machines, both cheap and outrageously expensive. The only time the belt was riding ANY roller was either due to bad assembly or a failing part. IE One of the vorons had an idler gone bad due to deformation of its plastic holder. One of my crealities had a bad roller pin, again the belt was grinding causing defects and motion issues.
Other printers would run straight. And yes I did check for that. I check EVERYTHING in my machines so i can reassure you , you are wrong. Yes very tiny slight deviations will appear. Belt grinding is not normal and people will start to understand why I make such a big matter of this in 1-2 months that this grinding will cause their belts to be bent sideways. Note my words. You just dont want to accept that the H2D is halfbaked from start to finish.
AI seems to think this is a very common issue. On both of my printers the belts ride from somewhere in the middle to riding up against the flange, same as the H2D. My CNC which runs on belts also exhibits the same issue.
I rest easy knowing this is expected and normal behavior according to Bambu. I believe that they know their stuff
You know what? Fair. Ill ride along.But Ill be here to say told you so.