Print Quality Issue, Overhangs, X1 Carbon, PLA

Yes I agree, this appears to be a software issue. Curious what build of Bambu Studio your using?
I’m using the latest public beta 2.

Tonight Ill go threw the maintenance manual, adjust my belts and just double check my hardware, rule out one before the other.

In my experience with other 3D printers and slicers usually this type of issue can be resolved by slowing down the print speed. Bambu studio isn’t very clear how the “slow down for overhangs” feature works and from my perspective it doesn’t appear to be slowing down at all. The profile defaults state a speed of 50mm for overhangs between 25% 50% and I can without a doubt definitely say my printer did not slow down to those speeds while printing the overhang torture test. The feature doesn’t appear to work at all. I spent 3 years printing at 50mm lol, I know what 50mm looks like. Another thing I noticed is the acceleration are extremely high durning this so called 50mm speed, which again could be causing some surface issues, one would assume as the overhang gets worse the software would also slow down acceleration.
Maybe I’m wrong lol.
I have seen others print the same models as me with the same machine and get great results so yah, I’m confused.
Anyone else reading this and not having the issue I would love for you to chime in and mention which version of Bambu studio your using, and which firmware your running.

I should of added that to my original post, I’ll add it now.

X1 carbon
Bambu Studio pb2

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I don’t use PLA filament but I recently had a battle with 60% overhangs using ASA and I can confirm the Slow Down for Overhangs features works in Orca Slicer but perhaps Bambu has issues. I only use Orca Slicer and find it much better. Bambu has an excellent Wiki on the feature here.

What worked for me was to slow the overhangs way down to 10mm/s and use 100% cooling on overhangs. Using a 0.6mm nozzle helps immensely too and would be a great fit for that particular model.


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Fantastic! Thanks for sharing. I tried orca slicer back on my ender and had mixed results so when I purchased my x1 I stuck to the official slicer assuming it was best to keep things simple, time to do some testing! I will give it a shot and post back my results. I’ll run tests using both Bambu and orca slicer and see if there’s a difference in the way it handles overhangs. Maybe it’s a bug in Bambu studio, if so I’ll report it right away. As for the 0.6mm nozzle, I don’t currently have one but I’ll order one later today. That said I wonder if increasing the line width would help any. I’ll test that too. Thanks for sharing your settings! Really helps.

Did you try to put your finger on the tip of the nozzle while letting the fan blow at 100%?
It does seem, that the cooling does not aim at the nozzle. It seems the airflow is a bit too deep and also concentrates its flow behind the nozzle not at the center. Can someone confirm this?

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Yes, I tend to agree that perhaps the part cooling shroud or fan is not up to the task. Unfortunately the fan is a slightly different profile than a normal 5015, so to fit a better high flow would require a redesign of the front cover. I do believe the duct could be better designed, something I hope to play with when I get a chance.
I tried slowing the whole print down to 30mm/s and for the particular model I was printing, it didn’t improve a lot. The slow down for overhangs does indeed work as you can visually see it slow down greatly but it still ends up with the filament pushed outside resulting in an ugly finish.

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Exactly and maybe thats the point why this speed setting doesnt help much. With other printers I dont have this problem at speeds around 30-80 mm/s on wall speed. I only have to reduce the speed for small parts. Also slowing down the print while maintaining this high temperature for faster printing is also the opposite of helpfull. Nearly all my PLA Filaments tend to curl on the X1C. The molten plastic gets dragged around leading to bad overhangs.

I tend to use this hollow pyramides as calibration tools to dial in my final retract, flow and temperature settings. They print beautifully on a good dialed printer (without z-hopping) , but its a big fight on this machine.

Hi @Rhotix
Thanks for sharing! I have included some pictures. Indeed the 5015 blower fan nozzles are offset and not directly blowing on the parts. This isn’t ideal but I don’t think its the sole issue causing poor quality overhangs.

Before I share this, everyone reading this: PLEASE DO NOT TRY THIS! I DID IT SO YOU DON’T NEED TO… LOL DO NOT PUT A CUP OF WATER INSIDE YOUR PRINTER… LOL Please… don’t do it…

Im not sure if I can upload a video here, I may share a private youtube link instead. I also took a video, the part cooling fan below 50% is useless lol It does nothing. So basically if your printing with PLA just keep it cranked to 100%. I think thats the take away here. We gotta keep in mind the AUX fan too, speaking to X1 user. I believe there is sufficient cooling, sufficient air flow. I printed for years with a single 5015 blower fan in a open air frame and never had overhang issues so keep that in mind. P1P users? I cant say. I still think its sufficient but i could be wrong.

I don’t want to get too stuck on insufficient cooling in this thread, I think its fantastic were talking about it and its great information but as I stated before the overhang quality issue happened with my part cooling fan at 100% and my aux fan at 70% (defaults), I will up the aux fan to 100% for my next tests but I don’t think its going to help much if any.

These overhangs are very bad, like lets be real, a $300 printer is making the x1 look like a bad purchase.

I want to believe this is software haha, oh man I sure hope its software. Because if not this printer is useless to me and that’s not a path I want to go down.

I will begin doing some tests tonight, with orca slicer, changes to overhang speeds and ill check my printer and make adjustments to my belts.

Ill post back with my results. Fingers crossed we can figure this out. I have yet to open a ticket with bambu, if your watching admins and have suggestions please speak up.

Thanks everyone who’s responded! Amazing community so far! All of you great! @RMB @Rhotix @azCubs76

Oh boy… Secretly this is my biggest fear… temperature and speed… slowing down while the nozzle is still over 220c isn’t going to do anything… The only fix would be running at 200 and reducing the speed of the entire print making the purchasing of a fast core xy a waste of two thousand Canadian rubles… lol Lets remain positive lol, but yah, I had this same thought today.

Ok… so this does not compute

Surface quality issues begin at 30%, very slight but there, 40% is a tad worse, between 45 and 50% overhang everything falls apart. The part looks incredibly bad.

Then something strange happens, we hit 75% and the quality returns, finishing 80% with acceptable quality… haha
80% top and bottom, completely acceptable for printing in literal air.
Now im really confused.

So the issue im having is between 45% and 70% overhangs, anything below is fine, somehow 70 and 80% is fine.

This test I did make some changes in the slicer, they are as shown in the images below. I also set my temperature to 215c instead of 220c.

Ill keep testing but… I think maybe its time to reach out to bambu.
Without being able to get logs from the printer… I cant tell whats going on in these layers. Oh i miss octoprint right now.

I think more than 45 degrees overhangs need support.
In my case i do careful construction to avoid bigger angles.
But i can only say this is the best printer i ever had and it’s producing stunning results in a short time.
The over all package is working well.
I used PLA, PETG CF, PAHT CF, and TPU (poor results)

Previous printers used

  • leapfrog XL
  • xyz printer pro
  • BCN3D Sigma
  • Bolt Pro
  • X1C plus 2x AMS

Thanks for the input, I think my last posts got a little sidetracked from the issue at hand, this isnt about how much of a overhang the machine can do, its about a failed print, multiple failed prints with overhangs around 25%. I just finished printing the speed benchy from the internal storage that has more overhang and got great results (See photo below) yet my print from a couple days ago, the one in my original post failed, terrible results. This is hopefully a software issue. I can replicate the problem, I have a friend who printed the same model on his x1 and didnt have the issue i had, I can show the issue doesnt exist with pre sliced models so yah, im lost lol.

I opened a ticket with bambu, for now ill put this post on pause and come back when bambu responds.
I dont think continuing to share my results is best until they look at it.

Please, anyone facing this issue speak up! Don’t get drowned out in the “nothing is wrong” category, this is definitely an issue that needs resolving and the more we talk about it the harder it is to ignore.

@mbruch im glad your experience has been amazing, if your using any custom settings your like to share with us please do! Any feedback is great feedback, thanks for sharing your experience with us.

Below is the picture i promised, ill monitor this thread but stay quiet till bambu responds.
Cheers everyone!


I forgot to add one more thing:
Those facing this issue: downgrade Bambu Studio from public beta 2 to
The issue is definitely worse with the latest version of bambu studios… Its not a full fix, but it helps allot.

Your tests scream to me that you need to check the “Slow down for Overhangs” settings!

Since 25%, 50% and 75% are all trigger points for speed changes it correlates perfectly with your problems. Have you tried setting those really slow like I showed before?


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I tried that and it didn’t do anything for the overhang quality. I also tried dropping all the speeds down to 30mm/s, there was some improvement but then it’s so slow I may as well just use my Prusa, which has zero overhang issues. I think it’s something else. My best guess is the filament is too hot for overhangs but needs to be hot for the fast parts and/or the cooling fan/shroud isn’t up to the task.

So… :face_with_peeking_eye:
My issue has been resolved :partying_face:
Shout out to @BambuLab for getting back to me overnight.
I’m still testing and need a bit of time before I talk about it.
I understand that might be frustrating but before I make a lengthy post and recommendations I need to verify them.
I’m not here to give anyone bad advice.

Also @azCubs76, thank you for your settings! I know I didn’t share my results yet but they did help allot and I will be using them in the foreseeable future! Unfortunately they were not the “fix” BUT in real world they have a huge impact on model quality. 100% can recommend @azCubs76 settings, think of them as extra insurance lol Great job man! Thank you for sharing.

Chat soon everyone


Hey there, this seems pretty interesting. I will do some tests too. What I know right now is, that using 0.16 layer height will result in way better overhangs as lower heights, which should not be the case.

Maybe its because of the geometry or because the nozzle is made of steel which leads to colder extrusion. One of the problems could be the longer meltzone heating the material intensive while the nozzle itself is rapidly cooling down the filament… Im running another thread precised on cooling issues.

Also I’ve ordered an aftermarket nozzle. Its 2mm longer and I hope brass will conduct the heat more even. Lets test the hell out of the machine to eliminate this once and for all :slightly_smiling_face:

Ok, lets talk about it.

Quick recap:
I came to the forums seeking help with an issue I was having with overhangs and surface quality. I had multiple failed prints, the largest being the alien hand featured in my first post. I was using the default 0.12mm profile in Bambu Studio on my X1 Carbon with AMS, only changes made to the profile were to infill.
The issue presented in overhangs, blobbing, poor surface quality on the outer layers.
I knew this model was able to be printed without supports, I had printed it before but not on this machine.

My X1 Carbon had less then 100 hours of print time, was only a week old. When I purchased and setup the unit I followed the instruction and was up and printing within the hour. Great experience out of box aside from some frustrating issues with the AMS and cardboard spools. Carboard spools you say? Thats a topic for another thread :stuck_out_tongue_winking_eye: Lets keep on track.

Yes, my problem is solved. I have been running my X1 for over a day now and can confirm the issue is gone.
Well… its complicated.
I will outline the steps I took and the instructions bambu sent me. There were multiple “fixes” I performed and I did them all at once so i’m not exactly 100% sure which one caused the issue although I have my theories.

  1. Hardware
    Maintenance the machine.
    When I contacted bambu they immediately instructed me to perform maintenance on my carbon rods and belt tensioner. They provided me with a lengthy and somewhat intimidating guide for cleaning the rods and adjusting the belt tension on my unit.

Step 1: Use IPA to clean your carbon rods.
My rods were filthy, bambu instructed me to clean the rods until no more black was rubbing off on my paper towel.
To do this I first loosened my belt tensioner screws on the back of the unit, 2 on each side.
Remove the top glass then carefully move the tool head to the centre and begin cleaning.
Make sure to use allot of IPA, bambu instructed I move the tool head over the wet rods so the IPA could get inside and clean the bearings. Don’t spray the toolhead, only the rods, be patient and let the IPA work slowly. I found soaking my paper towel was better then spraying, That was the method I used.
It took about 5 minutes, multiple paper towels until my towel remained clean.

Step 2: Belts
This one was tricky, the instructions bambu sent me were a little intimidating but once I took a moment to poke around back there I figured it out quickly. I’m mechanically inclined, im comfortable tinkering so this part went smooth for me. Before I loosed the bolts in step 1 I did check my belts, Y was allot looser then X but regardless both were way too loose.
The way I did was using a bed scraper to apply even pressure to the little tabs.

Instead of writing my own instructions Ill post what bambu sent me, to keep things consistent.

Here is a snip from out conversion.

1.Make sure the belt tensioners work as seen in the first 30 seconds in the video, after loosening the screws and turning the power off.

2: If the functionality of the belts is like in the video, not only clean the rods but make sure that the IPA will reach the bearings in the tool head by moving it over the IPA repeatedly. After this, clean the rods make them wet with IPA again, and move the Tool Head over the IPA and clean the rods again. Continue to do this until there is no more black residue. At that point, you are sure the bearings are clean and the self-lubricating function works.

3: Please move the gantry fully backwards and keep pushing the gantry to the back while re-tensioning the tensioners screws

Step 3:
This one was interesting. Previously I had my printers on a shelf build to save space. It wasn’t the most ridged shelf neither. The X1 is allot heavier then my previous printers and accelerations throw them around like crazy, creating allot of vibrations and flexing of the shelf. This is bad for 3d printers, the x1 likes a solid surface.
I know many of us struggle with space, its not easy to find a rock solid surface to put your printer. But… its kind of a must with these machines.
I spent the next hour or two back and forth in the shop cutting wood and reinforcing my self. By the end of it i could stand on them lol solid as a rock.
I see allot of people buying cheap walmart end tables or maybe ikea, these are not strong or stable enough for the x1. Now since were bordering opinions here ill leave surface topic at that, this is just what i did, you do you.

Step 4
Once your printer is back in its place, all hooked back up its time to calibrate it. Dont skip this step, the cleaning of the rods and re-tensioning of the belts changes how the printer mechanic behave with eachother, they need to be recalibrated.
To do this on you x1, using the printer screen go to Settings-Utilities-Calibration and ensure all 3 boxes are checked then hit strat calibration.
At this point walk away. Dont touch, dont open the door, dont lean on your wobbly table :crazy_face:
You get the drift.

And that’s it for hardware.
Personally, I think this issue was a hardware issue. My rods were dirty, my belts were loose, my shelf was wobbly. The combination of all 3 caused my poor quality print surface and overhang issues. Below ill post my results.

These are very acceptable prints, fantastic quality at full speed, default profiles. Exactly as I expected.

I spoke to bambu about my results, I believe this happened because like most new users I expected the printer to be fully calibrated and ready to go out of box. With under 100 print hours it was obvious to me the printer should of been inspected before I began using it. I suggested bambu change their setup guide to include the rod cleaning and belt tensioning in the initial setup faze. Yes its not as sexy as “yank it outa the box, plug it in and go” but it could of saved me allot of time AND taught me how to maintain my machine for the future right outa the box. This is important knowledge, your going to do this allot through the life of your printer. I don’t think this is a quality control issue on bambu side. My printer worked fine for the first couple days of printing. This isn’t something they would of caught in QC, and who knows what kind of journey my printer took across the ocean to my doorstep. In short, bambu if your listening please consider instructing new users to perform these tasks upon initial setup. Much love :kissing_heart:

Now… Im not done yet lol

  1. Software
    During my experiments trying to correct the issue in software I learned allot about the slicer.

Step 1
Downgrade Bambu Studio to
Yes, beta means broken. Never rely on beta software, never, never, always treat it as a test and expect it to fail.
I knew this… lol and stupidly ignored my own advice. Throughout allot of my testing I was using bambu latest build of bambu studio known as softfevers build and it is NOT ready for prime time lol
Sorry new P1S users, remember this thread is about the X1, I know you don’t have an option right now. I’m sure bambu will fix this as soon as they can.

So whats the problem in the latest bambu studio build?
No clue.
I noticed they changed the default profiles around for the x1, mainly the Arachne wall generator.
Im not going to get too deep into this, maybe switching it back to classic solves the surface quality issue, maybe it makes it worse. Just dont use beta software… lol Thats my answer. If your relying on this printer for commercial use, let others who are just playing around be the guinea pigs, stick with the basics.

Step 2: Don’t over-complicate your profiles.
Bambu develops and provides the default profiles for a reason. They work. Years of testing went into these machines and its safe to say the engineers over at bambu know best. Listen to them.
Don’t get me wrong tho, tweaking profiles is great as seen in the example from @azCubs76 and his custom overhang speed settings. I’m now using these settings in my default profiles, the theory to them and why they make sense + verifying = great success. Thanks again for your input!
It comes down to experience and the type of models and materials your printing.

I spoke about temperature, speed in a previous post.
Looking back at that now… I kind of regret bringing it up. I tend to think and overthink out loud lol circling back why would bambu include the speeds and temperatures they do in their default profiles if they were bad. No the x1 speed is not a party trick, it can and does print at its advertised speeds just fine.
If your really really concerned about filament temperatures I would first check with your filament manufacturer or better yet check your spool and see what they recommend as the max temp, most of my PLA suggests a print temp of 190-220c.
The generic PLA profile is within that range, and im leaving mine at the default 220c.
The test prints or results i posted above were all printed at 220c, standard mode, no tweaking to the profiles. Results speak for themselves.

Final thoughts.
Here we are, at the end of my crazy long post. I now have a working X1 that producing amazing prints in record time and I couldn’t be happier.
I hope this post helps anyone reading it. Never assume, verify! Be diligent, dont rush and enjoy it for what it is.
Please note that while these steps corrected my issue, it doesn’t mean it’ll correct yours. Reach out to bambu if the steps above don’t solve your issue, be polite and provide them with as much information as you can. Include a link to this threat, explain you tried all the steps listed and still have poor results. They can guide you forward.
Remember this post was never about getting perfect overhangs to 80% and above. I have been 3d printing for many years and most printers can achieve similar to the x1. Its the name of the game, use supports when needed, assume supports are probably needed and you’ll do fine. Allot of it comes from experience, trial and error. Years later im still learning and so will you.

Good luck everyone! I hoped this help. See you in the next tread :thinking:


Pretty nice to know, but thats not acceptable for my wish of getting 70° degree overhangs like on a V400. :grinning:

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Ive made some progress. Look at this link to stay updated.

65° clean with standart 0.12 settings are possible. Reducing the temp and go slower and/or using aux fan will give even better results.

I will upload the file soon.

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Taking a look at your print, my X1C can produce that same print almost flawless using the default 0.2mm layer height. I believe I posted pictures. Regardless. Your machine has an issue. I already outlined in great detail what those issues are possibly. Did you try to tighten your belts? Or clean your carbon rods? Make sure your printer is on a rock solid surface? And if you did then you need to reach out to Bambu. Add a link to this forum and politely tell them the tasks you’ve performed. They can assist you further. The model your printing is a stress test. It will never print perfect, that’s the whole point of the model. Even my x1c has ugly under hangs because it’s literally printing in mid air. No printer can print in mid air. I wasn’t even going to comment because of your last post claiming your other printer can do better… honestly that’s not what these forums are for, if you want to compare one to another make a different threat. This threat is here to help people who had the issue I had. My issue is fixed and so can your be if you just follow the guide. And if you have then you need to reach out to Bambu. Playing with slicer settings, speed, fan speed. It’s just an unnecessary rabbit hole. The default profiles are some of the best profiles made by the engineers who built the printer. Most people shouldn’t muck with them, they should be a base and modified slightly per model as needed but only if needed.
I hope that helps. This isn’t the threat for bad cooling theories. In fact I think the x1 has some of the best cooling out there. The aux fan works great. Most of the material I print “petg” I don’t even use cooling, or very little. Again it works just fine.