H2S clicking sound only on faster -X movements

Bambu Lab H2 Series Bambu Lab H2S
1

Hello!

Quick summary and details below:

  • This just started this morning, I’m quite sure
  • Did oil/grease maintenance yesterday when prompted - no problems after
  • Clicking is only on more rapid movements of -X axis (others seem fine)
  • No harm to print quality thus far
  • Can’t isolate precisely WHERE it’s coming from yet
  • Coincidentally, my tool cover is cracked, but cosmetic and not related (?)

I have about 465 hrs on my H2S and have been doing a lot of printing in recent weeks doing a large Gridfinity implementation in my lab and workspace. This is a lot of short and long (often overnight) jobs cranking out bins and grids.

Quality has been good and printing reliable all throughout.

I’ve done maintenance whenever prompted by the printer - I think twice now. The most recent was yesterday when I got the expected rod and screw oil and greasing reminders. I did it right away as per normal, cleaning a good bit of black dust (using matte black PLA for this) off the various parts.

I resumed multiple back to back jobs afterward with everything seeming normal.

This morning I started another job and, while sitting here, noticed I was hearing a clicking sound I’m not used to hearing. I poked all around and couldn’t find anything that seemed loose, rattling, etc.

After the job finished, I ran the homing multiple times as well as manual control movements. I’ve narrowed it down to -X movements making the click. +X and anything Y seems fine. It also seems to be on larger, more rapid movements… slower movements (like most things first-layer related) seem normal.

It’s not causing obvious print issues of any kind, but it’s mildly annoying (as much the sound as knowing something isn’t “right”) and I do want to head off anything that could develop into a quality or downtime issue.

Do note that I hear this when homing/moving the head even when not printing, so there’s no relationship to the buffer or extruder or anything else here… seems to be totally -X head movement.

I took the lid off and listened and I can’t hear it as well as I can from the front or back with the door shut. I think that’s partly fighting fan noise in that case making it harder to pinpoint. But I didn’t seem to find it louder (it seemed harder to hear, in fact) when focusing on the back right corner (as seen from the front).

A strange side note: I also noticed the cover of the tool head is cracked diagonally from the clear bubble rightward. I have NO idea how or why. I’ve not removed it recently and I looked at some photos from recent days that happened to show the printer and I don’t see the crack. As much as I look at and hear this thing, both issues are definitely new (perhaps even overnight, though it was mostly idle after a short job as I went to bed).

The cracked plastic cover has no effect - it’s just cosmetic, I think. I removed it and the little wheel under the bubble during my homing tests and the click was still there. Odd coincidence, perhaps. I’ve asked if it can be replaced under warranty and waiting to hear back.

Would love any thoughts or insights on what else to check!

2

Probably your drag chain hitting the right side led light or foam pad underneath.

2 Likes
3

Quick update: I am running the calibration where a lot of movement without fans makes things easier to hear.

If I’m not mistaken, during the motor noise tests, leftward movements that made clicking sounds were only the ones involving the leftmost stepper. There are two phases of the test where I only see one of the two steppers actively turning. I didn’t hear it on leftward movements with the right stepper active, but did during the ones with the left stepper active.

Also, I’m including a short video clip where you can clearly hear it with the leftward movements:

Again, appreciate any insights.

4

Did you updated to the beta firmware by any chance? I only ask because it’s very similar to a problem i reported yesterday

5

Looks like to me the chain is hitting the wall. The very least the chain hits at the exact same time as the click.
Just my 2 cents.

2 Likes
6

Nope, haven’t been using beta firmware… on whatever the latest prod release would be currently.

7

Quite sure that’s not it. The chain does touch the wall (which is, for the most part silent or a known sound on my unit)… but the clicking I’m talking about is happening on the leftward movement away from the wall.

Am I misunderstanding your thought here, though?

1 Like
8

I have a support ticket in with Bambu, so will share what the ultimate determination is on this issue.

Meanwhile, I’ve been digging more deeply into the issue and can say with certainty that the problem only happens when Motor B (the leftmost as seen from the front) is moving. The motor noise calibration process does run each motor individually for a while, so it really helps with narrowing things down.

I took the back panel off to see if I could find any obvious issue. Visually, it all looks good. Nothing you touch feels wrong and nothing you apply pressure to alters the clicking in any way whatsoever. I don’t see issues in the belt or any debris.

I’m including two more videos - one shows clicking when Motor B runs by itself (no Motor A):

The other shows Motor A running by itself and no clicking:

I wonder if this is the sound of a failing bearing?

9

Hi,
Did you happen to check the small bearing on top of the engine pulley that you say is making noise?

Immagine 2026-03-16 235136
Immagine 2026-03-16 235136535×562 39.9 KB

10

Well, in this case, the one clicking is Motor B - so it would be the downward facing bearing opposite the one in your picture, correct?

In any case, can you elaborate on what/how to check? Removal of the belt and spinning it manually, etc?

Thanks!

11

Yes, sorry, you’re right, it’s the engine with the toothed pulley facing downwards…
To check, as you say, perhaps the best thing to do is remove the belt and check the bearing.

But before removing the belt I would wait for the response to the ticket you opened…

12

Quick update that Bambu replied on only our second exchange on the topic that they are sending me a new XY motor. I provided all the same info and videos proactively that I’ve been sharing here, so I guess little need for a lot of back and forth. They didn’t elaborate or ask for additional tests, so I’m hoping this suggests a definitive and recognized issue that the replacement will address.

Also sending a new tool head cover since mine inexplicably cracked in place (just found it like that the other morning out of the blue).

Will report back on the process and the outcome.

Thanks!

1 Like
13

I look forward to your feedback, thank you very much in advance.
Let us know if the problem was with the motor itself or with the small crankshaft bearing.

PS: May I ask when you purchased your H2s?

Thanks.

14

Hello!

Yes, very glad to share! I upgraded from my X1C (which was an all around fantastic printer and experience) last September. The X1C never gave me issues and a friend bought it. This H2S had a model detach and built up a glob so bad that I couldn’t rescue the hotend heater and its wiring from the mess. The printer didn’t detect it… I just happened to hear a noise and it was the sound of the tool cover falling off due to the glob growing so big. To their credit, Bambu replaced the heater under warranty due to the lack of any detection that allowed it to get that bad.

This clicking just started a few days go. On the same day, I found an unexplainable crack in my toolhead cover (not related to the above - that was a few months ago). Again, Bambu has been very quick with their support and is replacing both items under warranty, so I can’t complain about support whatsoever.

I feel like print quality still isn’t QUITE where my X1C was, but it’s awfully close and maybe has caught up over some of the firmware updates. There are so many variables in 3D printing, of course… so I try not to get overly paranoid about quality comparisons. It’s a rabbit hole.

I felt a month or so ago that I was suddenly starting to hear some fan noise in my fairly quiet room that wasn’t there before. Traced it quickly to the power supply fan. I couldn’t be sure if it was new or me just noticing somehow (but seemed doubtful since I’m pretty aware). Just a few minutes ago I took out a print and when the door thunked shut, the power supply fan started making a REALLY loud sound that would moderate if I tapped lightly on the back grillwork. I know it’s clean because I wiped any dust off it when I had the panel off checking this motor issue. A few moments later it went back to its not-quite-as-quiet-as-it-was-when-new level. So I might have motor bearing problems in that fan now, but I can replace that myself with a very quiet Noctua if it comes to it.

Just hope these are flukes, because the X1C to H2S comparison is pretty stark right now on reliability.

15

Hi,

Thanks for the super detailed reply…

I used a P1S and sold it to receive the H2S in early December 2025.

The difference in quality between the P1S and the H2S was noticeable for me, but I’m a little concerned after hearing/seeing online about issues with the stepper motor bearings. I hope you can solve your problem, even though I understand it’s a huge hassle. I also tried installing the beta firmware but reverted to version 01.01.02.00… The printer seems to work better and with smoother movements. There are no more noises (like clack clack) from the Z-axis movement during bed leveling or during Z-hop while printing.

2 Likes
17

So I finally had time to do the Motor B replacement today after the parts arrived last week.

TL;DR: it appears to have fixed the problem, which has me pretty pleased. Best I can tell, the clicking on the -X direction appears to be gone. Things are back to normal.

It is, however, a real slog getting through this swap.

Longer version: if this happens to you, hope it’s motor A and not motor B. :slight_smile: This was NOT the most fun bit of repair work I’ve had to do. Their guide (note the links to two or three sub-guides for sometimes non-trivial steps along the way):

covers it all quite nicely, but do look at the added steps for motor B (vs. A) due its location. I’ll point out the fun of replacing the AC cover, though it’s not hard once you realize which wires route where and note at least one difference between your H2S and the image (most likely). But it’s exceedingly fiddly.

Worst, though, is the motor itself. The screws can only be reached using the long Allen wrench that comes with your printer, aligned through holes that well precede the motor’s screw holes by a decent bit. You’ll find yourself needing or wanting to be in the back and the front of the printer simultaneously and doing a lot of stuff by feel while holding your mouth just right. Worst of all, the two screws closest to the wall don’t have clearance to permit the wrench to turn fully thanks to its elbow, so you only work in quarter to maybe half turns at a time, each time having to reseat the wrench blindly into the head of the deeply set screw and feeling for tension. It’s tedious beyond words and you’re going to be contorting your upper body much of the time.

I found working from a stool above the printer through the top opening was best for two or three of the four screws. The screws are VERY tight and you’re instructed to replace them tightly, but also magically NOT strip the heads (I didn’t strip them on removal but I can’t readily tell on replacement and I’m not about ready to try to back any of them out again to find out).

Nothing I removed - a pulley that didn’t get swapped - nor the old motor exhibited any clicking sounds or hitches in movement when I had them free of tension and out of the printer. I twisted and spun and fiddled with them and couldn’t find signs of the source of the sound. This worried me during the painful reassembly process (that I was wasting my time), but I was thrilled to find the printer once again quiet in this regard.

The ONLY difference I could feel was that the new motor, when spinning the shaft with your fingers, had more distinct “detents” in its action vs. the motor I removed. The old one felt like it spun more “smoothly” and the detents (which should be there, of course) seemed less obvious. Beats me if that means anything. I think the “detents” I’m describing are what you’re feeling in the action of the magnets inside.

For all I know, the less than fun process of removing and replacing everything jostled something back into condition that had nothing to do with a failing motor. I did NOT find anything that felt at all loose in terms of screws on any part of - especially the motor.

But it’s done, the printer seems to work and is running all of its calibrations as I write this without the clicking sounds you hear in my videos above.

Here’s the ironic frustration, though: in the days just before I did this replacement, the printer started making an additional, new and pretty annoying clicky/squeaky sound when it gets rocking. More click than squeak, but I just about wanted to slam my head in a door with another annoying noise developing. I can’t seem to isolate it, but I can easily reproduce it wobbling the printer on its base. Maybe something in the feet… maybe some plastic bit rubbing now… I literally cannot find it. I checked for it throughout this replacement process hoping I’d find a plastic bit inside rubbing or something… but no sign of it. I hope to fix that, too… but at least it doesn’t sound like a pending mechanical issue like this one.

Sorry for the long description, but I hope it helps others in the future! Also, love any thoughts on the wobble-click. :slight_smile:

1 Like
18

mine does the same but lesser noisy and on the other motor. I already opened a ticket, they said it is “normal”, asked if it’s possible to remove and clean the bearing, no response on that.

Noise went away while printing ASA. 100% present if I print cold stuff. is 100% the roller bearing in my opinion. I printed hundreds of hours like this, prints come good, it is just the noise. It is like a bit of pla or such did melt into the bearings and It is still there, grinded to the infinite.

I just ignore it

1 Like
19

Hi, first of all, sorry for the delay in responding. Second, I’m very glad you finally solved the problem, and third, thank you for the super detailed reply (I admit I wouldn’t have had the patience to write such a long text…). That said, I read what you wrote very carefully and honestly, I never expected the noise to be caused directly by the motor itself, but rather thought the noise was caused by a bearing. (Unless the cause is a bearing inside the motor, but from what you described, I don’t think so.) I sincerely hope that the failure of motor A, or even worse, motor B, is one of the problems with a low percentage of cases. Thanks for sharing your experience.

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20

I agree with your thoughts.

It was Bambu that opted to send me a motor and not a roller bearing replacement… so I went with it. As I mentioned, though, I can’t be sure if that was the issue or if something got sorted in some manner in the process of replacing it. I hate not knowing for sure, but glad the issue is gone in any case.

1 Like
21

I agree with what you say. If Bambulab decided to send you a new motor, it’s because they obviously already knew what the problem was. Even though replacing the motor was more complicated than just replacing the bearing, at least it solved the problem permanently. I’m glad everything was resolved. Happy printing!