Was it a new unit that had this problem from the beginning or did this happen after hours of use?
The exact same thing that @Drazel is seeing with his flow rate calibration, I’m seeing in mine. Every single result is awful for multiple filaments.
I’ve had it for almost a year though and this just started in Nov/Dec
Did some test squares. The squares are .6mm tall. The layer heights are all .2mm.
The 45º top layers look awful, the 90º and 0º look, okay? They definitely look better but they’re not perfect.
Here are some other tests, with seemingly no change in results…
The diamond was printed with 5 walls, which look fine other than my PA clearly being a bit off making the corners look awful, but the walls themselves look fine.
Slowing down helps, kind of, but you can clearly still see and feel the imperfections. The .7 top layer flow was a shot in the dark to see if I could get any noticeable change.
I’m honestly at a loss for what is going on. I feel like the top layer flow test with 1.3 top layer flow should have had a very noticeable difference, but it really doesn’t.
I’ve had the same issue at work with an X1C since Valentine’s day (what a way to show love), did a cold pull, cleaned the rods 3 times thoroughly with Isopropyl alcohol (same procedure as on maintenance wiki page).
I’d vouch the solution as effective. Pure speculation based on my outcome, but I think it could really just be a matter of friction from the rod. The weird top surface pattern is mostly apparent because of the zigzag not aligning “perfectly” like usual. The print head(X) lagging behind the gantry(Y) makes the line widths overlap slightly, ruining top surface finishes. Anyways, it worked for me, and I was able to calibrate my new filament properly and resume activities in a jiffy.
Hope this helps!
Unfortunately I’ve cleaned the carbon rods numerous times at this point. I’ve also taken apart the toolhead, dusted and cleaned all the gears. I’ve also done hot and cold pulls as well as running cleaning filament through it.
I guess I’m at the point where I need to just talk to support. I can only assume my carbon rods are faulty and need replacing. Not looking forward to that.
I also don’t understand how everything can print completely fine except the top layer if the carbon rods are faulty.
I’ve opened a support ticket. I’m really hoping the issue isn’t the carbon rods.
Unless I’m completely wrong, which I could be, the issue could also come from the Y axis linear rods. If that’s the case, the same solution should apply, cleaning the Y axis rods (on the 2 sides, so 4 rods) to remove friction.
Y axis linear rods cleaning
Edit: 2 rods, one on each side, my mistake.
@Genox , @nickam1025 This worked for me on 3 of my printers, still having a problem with another one though.
It looks like underextrusion is an issue, but the other machine is printing fine? This could be a possible partial clog. The internal infill pattern I would switch to Monotonic line for that print.
I think there are only two Y axis rods, unless I’m mistaken, and I cleaned those as well and lubed it up with https://www.amazon.com/dp/B00175VGUA
I want to see if Bambu support has any insight since they can read the logs, but if I get impatient waiting for them to respond, I will give everything another good cleaning and try again.
I have a similar issue. I printed 1 part and came out perfectly. I have since tried to print same print 5 times and both far right and left side .500 in X look like ■■■■. But only the last top 5 layers. The model is using 2 colors and both colors look like ■■■■. I have tried PLA and ABS. At first i thought maybe it was lifting but it is not. The middle of the print in both colors and both types of material are smooth and perfect. X1 carbon all calibrated bed leveled. Its very rough like for some reason it starts to over extrude but only on small portion of the print.
My problem happened out of nowhere after about a month of use. After working with support they sent me a new x-axis carbon rod assembly to swap out. It was a pain to swap out but it completely fixed my issue. Was back to printing perfect.
FYI, support had me send them some logs and they detected “excessive friction” which led to them sending me the new carbon rod assembly. My guess is something broke in the bearings or got jammed in there. I didn’t notice any marks on the old rods but with how fast the printer moves I wouldn’t be surprised if it only took a tiny bit to cause issues.
I have been having the same problem for a long time and I could never find a solution. I have tried everything, including changing Exetruder gears, changing nozzles and flow calibrations, and there was never a solution.
Can anyone find the solution and share it here?
I have the same problem and have already been in contact with support several times. Sent logs several times. Photos and error descriptions updated in the ticket, etc., The print bed is also bent (seen from left to right, the print bed sags quite a bit), so that the print bed moves up and down all the time during printing. Feedback from support: for them this is within tolerance and the ticket is closed.
This is really not satisfactory. Especially because the printer had been printing perfectly and suddenly produces a very rough, poor surface.
Hello,
I would like to show my progress to solve this problem but I can’t upload any images, why?
Thank you
Because you’re still classified as a “New User” which means that you have a limited account. Looks like you need to read 3 or 4 more topics to advanced to a “Basic” user which allows you to post pictures and new threads.
@JonRaymond Thank you 
Hello gentlemen,
started to have the same issue as everyone and I see that some people solved the problem differently than others and meanwhile someone still has the same problem.
I would like to share my way (or rather a non-permanent patch) that I use to solve this problem:
I’m using the 0.2mm preset of BambuLab studio, the only parameter I changed is the INFILL percentage; some parts need more strength than others for my project.
The filament is PolyTerra PLA, and yes, fresh and new from the box.
All parts printed with a 15% INFILL rectilinear have no problem with the top surface; the problem occurs when the INFILL is increased at 80%.
It’s really bad…
I tried to do a flow rate calibration and re-printed the same part, nothing change and very different from the piece printed in the flow calibration:
Then I though: all parts printed with a 15% INFILL look good and all the pieces printed in the flow rate calibration look like a 15/20% INFILL (correct me if I am wrong).
So I re-printed the same part but with the same INFILL (15%) and this is the result (right one):
Much better!
It seems like the slicer does not take into account the INFILL and always pour the same amount of filament: in a case of 15% INFILL some filament will “bend” or “fall” inside the gaps of the INFILL leaving room for the last 3/4 top layers, while with an 80% INFILL there is no room for the overextruding top layers thus overlaping on each other making the extruder touch the last top layer living marks.
I decided to print again with 80% INFILL BUT with the flow rate at -5 and skipping the second step of the flow rate calibration
Well would you look at that, now 80% and 15% are the same.
TOP: 80% INFILL flow rate 0
MID: 15% INFILL flow rate 0
BOT: 80% INFILL flow rate -5
To make sure that the new flow rate does not affect the 15% INFILL profile too much, I printed the part again at 15% INFILL with the new flow rate:
TOP LEFT : 80% INFILL flow rate 0
TOP RIGHT: 80% INFILL flow rate -5
BOT LEFT: 15% INFILL flow rate 0
BOT RIGHT: 15% INFILL flow rate -5
And compare with the pieces of the flow rate calibration, completely different! The -5 from the calibration have gaps, meanwhile the finished prints do not.
Now, as I said, this is not a definitive solution because it varies from the type on infill, the percentage, materials, etc… but I think an automatic “X factor” flow rate variable based on the percentage of INFILL would be very useful.
Or maybe there is and I’m not aware.
Maybe I just discovered hot water?
Do you think the K factor would help? I have a P1S so no auto calibration of flow and I don’t even know if I can use that parameter.
I never touched it because at 15% the prints always came and still come out fine.
If you have the same problem and in the flow rate calibration the 0 piece is the best, try change at -5 (or +5 if under extrusion) and see if that helps.
Have a nice day 
As someone has already mentioned, it’s best to report the issue to Bamboo. The logs indicate that there are stresses on the shafts and carbon rods need to be replaced.
I have a X1C delivered at the beginning of February and I am using Bambu Lab filaments.
All of the sudden some prints started to have rough top layer only in certain zones of the print, the others are very good. I saw that a lot of people is having this type of issues, so as suggested here I opened a case with support on February 18th,.
The first reply finally arrived on March 1st after almost 2 weeks; I have added some more pictures because the issue is worsening at every print and today I am still waiting that someone from the support follows-up. Another week from their only reply and 3 weeks from the ticket opening. Like so it will require ages before I address the issue. 
FWIW, my issues were finally sorted with a replacement carbon rods gantry (a nightmare to install), and new extruder gears (after almost 4,000 hours, my original set was VERY worn).
Though I still run cleaner filament through the machine every week or so, and also do a factory reset after FW updates.
Okay, I can confirm, mine was the same issue. They sent me new carbon rods, which weren’t too bad to install (belts were a pain to remove), and after ~5 hours it is printing smooth layers again. It is also significantly quieter than it has ever been. I’m wondering if mine was defective from day 1 and I just never knew.
Only advice I can give anyone who has to do the same replacement, organize your hardware as you remove it. I literally put every section in separate baggies and still managed to lose 1 bolt. Luckily I had a spare.
Same for me - I found this post when trying to diagnose poor top layer quality. Printer only has 90 hours on. Went through all the cleaning, maintenance and calibration steps. Eventually identified issue with the carbon rods, are sending replacement.
