Beware of creaking noise, it might be your extruder gear failing

Bambu Lab H2 Series
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I suddenly had a very poor result while performing a high precision offset calibration, I had underextrusion, bad layer adhesion etc things that never happened before.

The only thing I did before this was trying the 0.2 nozzles and this happened after I switched back to 0.4 nozzles.

I redid the calibration and the only strange thing was some creaking sound during the flow calibration of the process that I had not noticed before, calibration failed again with same results.

I checked nozzles, try other filaments, different AMS, remove the back splitter thinking the sound was coming from there, same results. At my 5th or 6th attempt, I finally had a fault message for an extrusion issue.

I then decided to dismantled the hotend and check everything. Apart from some filament residues that were not in contact with anything which would have caused an issue, I checked the gear remembering one of the user that had experienced slippage between gear and extrusion wheel and voila!

Extruder gear
Extruder gear1590Ă—1389 423 KB

I did not exactly find it like that but although the extrusion wheel was still on the shaft it was a little tight but not tight enough that it couldn’t slip relative to the gear. That was the creaking noise I experienced when there was micro slippage between gear and wheel.

I suppose it was OK until I used the 0.2 nozzles which may have required higher pressure which exacerbated a certainly existing condition.

If you hear strange creaking noise during auto flow calibration or you have bad adhesion, underextrusion, bad surface quality, missing layers in your print, check your gear!

Edit: I opened a support ticket but in the meantime I just put a drop of superglue on the shaft, my prints are perfect again :wink:

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Seems like a bad design to me, these two parts should be “pressed” together. While they may have been press fit originally, it’s obvious that the tolerances of the fit was too loose. Loctite 603 would be a great choice to really lock them together again if the CA fails.

Thanks for the heads up, I haven’t experienced it yet. I do have a couple of .20 nozzles that I intend to put to use so I’m going to pay close attention when I change over to them.

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Isn’t it too soon for such things to fail? And people call me crazy for freaking over the belts grinding themselves to dust while almost derailing from the rollers.

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It was a poor design. I called it out a while back and guessed that it would be an issue once people got more hours on them. My laser edition is still down because of it. Ill probably just order a new toolhead and use some permanent loctite. After a couple back and forths with support, I remembered why I hated bambu support. Its a pressure fitted part in a machine that constantly heat cycles. Pretty obvious this would be an issue over time. As the part starts to slide off, it pinches the filament in its path. Probably what causes extruder issues for people in this forum. They just havnt realized yet.

@LarryCnAZ has the right idea. CA glue weakens when heated

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I have some loctite 603 but didn’t even think about it, surface in contact is large enough I think CA may hold but if it doesn’t I know what to do :wink:

gear
gear800Ă—616 21.9 KB

I had some misses on my prints that I put on glitches or slicing issues, when I re-sliced and reprinted they were then perfect but I wonder now if it was not it. You may not even notice the gear loosens until it develops enough to become obvious. I think the pressure advance calibration put more pressure on the gears than regular printing flow and if you don’t use it or only once in a while because you calibrated your filaments or always use the same it might just go unoticed.

The thing is if you include dynamic flow cal in your print and there’s micro slippage of the wheel, PA will be way off and you get under or over extrusion. If I knew firsthand I would have tested with and without PA cal before I fixed the gear.

I’m the second user on this board to experience it as far as I know but I wonder if it’s not a wider issue given the poor printing some experienced, it might be more common.

If it is (not reported on the board but with @supportassistant) bambu will come up with a better design or advise the manufacturer to improve the press fit.

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Looking at this thread, it looks like 4 or 5 users have already had the same issue and on at least 2 occasions, support asked about it, might be more widespread than just a couple of users…

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At least if there is an issue with manufacturing, it’s an easy fix in the long term, they just release a better version to either buy or warranty replace. I’m not to worried overall.

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Support was easier for me, filed a ticket on Sunday, received an answer this morning that the part is on its way.

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Because you are overreacting in that thread and LOL the belts are not “derailing” jfc

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Use Loctite super strong thread locker (the green stuff) → with this stuff we glue gears on 2 KW E-Motors without getting lose even in harsh conditions

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Interestingly enough, I’ve already addressed the issue myself—and, as it turns out, it was quite serious. But by all means, feel free to trust whatever narrative you’re most comfortable with. I’ll be watching quietly as this exact problem begins to affect others, likely leading to belt deformation and machine damage.

For context, mine catastrophically failed just four prints after I last raised concerns about the belts. No, I won’t be sharing photos—there are already enough examples out there. I’m holding onto my documentation for support purposes, should the situation escalate.

That said, I’ll refrain from further comments going forward. The dismissive and often arrogant attitude toward genuine concerns has made it clear that constructive dialogue isn’t always welcome. So I’ll step back and let reality do the talking.

Ham, signing off.

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Don’t get butthurt because one random internet person popped on your input. I and probably others concerned want to know about the details, appreciate you adding light to the issue, and hope you’ll continue to share details. :).

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Mind posting the convo? So people can see how its done in 1 message.

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The bottomline is to use simplified English, simplistic even, no idioms, no very technical or complicated terms as you never know how fluent the support guy is and keep it short. If he is really fluent in English he might think you’re not but that’s OK if it means handling your ticket quickly :wink:

This was my ticket:

« Suddenly my prints were bad with underextrusion. Extruder made creaking noises when performing automatic flow calibration.

I removed the tool end components and found that the extruder gear and the extrusion wheel were not fixed to each other. The gear could be easily removed from the wheel, see picture. I temporarily repaired it with a drop of superglue but I’m afraid it will not stay with the heat of the hotend. I need a new replacement extruder gear assembly.«

And this morning :wink: :slight_smile:

« We are pleased to inform you that your replacement is currently being shipped byDHL.

You can easily track your shipment by clicking on this link: xxxxxxx »

Edit: I also included Full Name, address and phone number with my request and I always add , Dear support, Thanks, Kind Regards, etc. I also thank support when it is resolved so may be I’m treated as a nice customer in their database as my tickets never took more than 3/4 days to get resolved but really this issue was easy, part failure —> replacement.

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I purchased an all metal one from Biqu a while back - haven’t installed it yet, but someday…

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For H2D?

252525252525252525

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I received my new extruder Today, can’t say if it’s an improved version as it looks exactly the same. On the original I could see some white stuff (epoxy glue?) at the bottom junction of the wheel and gear but not sure it could be seen without the press fit actually failing and none on this one. I tried to rotate (not too strong as I don’t want to ruin it) but it seems really tight.

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The extruder assembly is very similar to the one on the A1 and Mini. In fact, some Chinese manufacturers have already made extruders (for A1 series) as a single block. I wonder why Bambu doesn’t do the same.

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I found this one, It’s not clear whether it’s a single solid piece (and not two press-fitted parts) like many aftermarket options for the A1 series, but given the price…

https://it.aliexpress.com/item/1005009750132813.html

image
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Update to my issue… Well, the superglue did not last. I started experiencing underextrusion again, good thing is it was exactly as before so it was easy to troubleshoot. It was even worse as I an now using a HF nozzle and the preset for infill is very fast, the extruder could not keep up with the speed.

So if it happens to you, don’t use superglue to repair, use high strength thread locker. I haven’t used it yet as I simply replaced it with the one BL sent me and everything is back to normal.