Maybe its since I re-tensioned the belts some weeks ago, but I am not 100% sure.
I observe the following about this patterns:
When I print something multiple times (same number & type of objects and same settings), the pattern stays the same.
But when I change e.g. the number of parts I print in parallel, then the pattern change:
there seem to be some linear correlation between how much I print and how small the pattern gets, e.g.:
group of 49 shells: the pattern repeats every ~6mm (every ~15g/55min filament one repetition)
group of 36 shells: repeats every ~8mm (every ~15g/55min)
group of 25 shells: repeats every ~12mm (every ~15g/55min)
group of 110 links: repeats every ~1.1mm (every ~15g/55min)
big cylinder: repeats every ~3.5mm (every ~6g/25min)
white big part: repeats every ~6.5mm (every ~13g/44min)
(not sure how precise these measurements areâŚ)
I tried different filament colors, two different filament provider (Bambu PLA Basic, Redline PLA), a different printer (Prusa MK4): The issue always appears on the X1C, but never on the Prusa MK4
same behavior on different speeds (I also printed preeeeeetty slow with not improvement of quality)
same behavior when I disable print bed heating (set the target temperature to 20°C and I am not living in the Arctic )
Since I noticed this issue I re-tensioned the belt multiple times, once how the Bambu Support page said, once with higher tension and twice how this video suggested: https://www.youtube.com/watch?v=izdBZ9IQfqI&t=1s
Sadly, the pattern didnât go away.
I am struggling for weeks with this problem, please help me!
First, thanks for posting details. This is very helfpul.
Itâs clear that youâve been able to establish that this is mechanical in nature by citing the different filaments and models. However, Iâm not sure if there might not still be a solution in the slicer.
If I understand you correctly, youâre saying the problem worsens when you have more than one model on the plate. Have you tried âprint by objectâ? Note that youâll need to space the parts farther apart so the head doesnât collide with the other parts. If you havenât used this feature before, it works by printing each model completely before moving on to the next. If the nozzle movement between parts is causing issues, this might solve or at least mitigate the problem to some extent.
The other thing you did not mention. Is there an AMS involved and if so have you tried running the print with an isolated spool? While I doubt this is the issue, it simplifies troubleshooting.
Also, may I assume that you cleaned and re-lubed the z-axis lead screws? Again, this doesnât look like the issue youâre showing but itâs one more variable to remove from the troubleshooting equation.
And the last thing I can think of also related to single spool isolation. How old is your PTFE tube and have you tried repositioning it? I only ask because if this is being influenced by uneven filament flow, the PTFE tube could be a contributing factor.
There is quite a few topics now in regards to those issuesâŚ
Let me sum it up very quickly:
Proper filament calibration is a must.
With that the problem will be less but not gone.
The layer times differ, which means the plastic has different times to cool.
There is no fix for that with Bambu, at least none that eliminates the problem for good.
The problems get worse with the increase of difference for the layer times.
The problem gets worse the more speed variations there are during a print.
Using a low nozzle temp that still provides good layer adhesion is better than running too hot.
The later is especially a problem if you want to print fast.
In the slice you can see the speeds, flow rate and more - use this to see where you might run into trouble.
Give this a try:
Print these single cylinders just as tall as required for these affects to be visible.
But print the outer most wall FIRST.
In case this provides a meaningful improvement chances are that you have to properly calibrate your filament before running into walls that you can get through using doors
I checked the PTFE tube, IMO the filament can be pushed in smoothly
I removed AMS (before I was printing with one) and also removed the PTFE tube, putting the filament directly into the extruder (see picture below, not a very clean build, but if ptfe tube / AMS would have been the reason, now it should have been not visible anymore / only other issues visible )
I also put cylinders near each z lead screw to check if the symptoms vary
The result: The issue still appears on all cylinders
But the idea with âprint objects in sequenceâ is pretty good. I could bring up to 4 sets of 10 cylinders groups on one print bed, so 40
Sadly e.g. the grey big cylinder thing is printed alone and is still getting the mentioned symptoms, and other bigger parts are waiting.
I already did a filament flow dynamics calibration manually (where the result is a k value) and this didnât change anything. Did you mean that?
About the layer times and print speed / flow rate: The pattern are visible on the straight surface of the cylinders, there each layer is nearly the same, and should also take nearly the same time, right? here you can see the speed of the layers
That last photo helps understanding a lot. Iâd say you have pretty much isolated any mechanical interference with the way youâve set up the spool. Hell⌠you even gave it a gravity assist.
At this point, I think itâs safe to say that youâve pretty much exhausted all the troubleshooting steps one can reasonably be expected to take. Itâs time for a request for warranty repair.
On last thing I thought of: Maybe the belt of the z leading screws might be too loose? For sure its a lot looser than the other two belts (after the belt tensioning using only the springs as suggested on the bambu support page)
The additional photos are a strong indicator or even âproofâ of mechanical issues. I would even go so far as to say a smoking gun. Either way, you will want to strongly consider replacing the belts. But you have to ask yourself, do you want to run the risk of an out-of-warranty repair. If nothing else, open a warranty ticket so at least you pause the clock while you self-diagnose.
You seem like an independent-minded person who prefers to find your own remedies. I totally identify with that vibe. I believe that if I can figure out how to fix something, thereâs not only the convenience of immediacy and continuous product use but also a sense of empowerment in being self-reliant. On the other hand, does it make sense to risk the financial impact of not getting a warranty repair? Only you can balance that equation. But definitely get Bambu to send you either free belts or order some spares.
Theyâre not that expensive and it may just be peace of mind having some on hand.
When you tension the belts, and retighten the tensioners, assuming you donât break them by overtightening, itâs possible to tighten them with a âskewâ, the tensioner ends up tilted. That will cause the belts to ride up or down on their pulleys/idlers depending on which way the tensioner is skewed. Check this, since it may explain your beltâs shifted position.
This wouldnât account for your Z banding problem, though.
[EDIT]
Iâd go back to the Z screws. Cleaning them is important. Lubricating them is important. But too much grease can be as bad as not enough grease. Wipe off any excess you can see, then go in to the control panel for the printer and run the Z stage all the way up and all the way down a half dozen times. Then try another print.
outer most wall first
sadly this didnât help either
In general, I want my machine to just work. I am under time pressure thatâs why I spend so much time in getting it working again⌠also I donât like to waste the time of the support team when there is a common knowledge about a solution for my problem - I think they (with their internal knowledge) should be used for difficult cases
But it seems like there isnât an easy fix for my issue⌠so I will handle that via the bambu support.
About the belt tension I did it is this youtube video said (regarding the tilting of the pulleys): https://www.youtube.com/watch?v=izdBZ9IQfqI
but this didnât help. I will clean and move up/down the z stuff but I donât think it will help.
I contacted the Bambu Support and they wanted to send me new XY-belts - first I doubted that this would solve the issue, but I did it anyway.
So I cleaned all pulleys (there was some stuff on it, maybe from the belts), I checked that all pulleys move freely and then I installed the new belts.
Now the issue is completely fixed!
So my suggestion: Contact Bambu support, they will probably send you new XY-belts, then you invest some hours into replacing them and then your printer is as good as new
Thanks for closing out this topic with news of your success. Itâs always a great help when folks share their success with the community, like you did just now, when they actually find a remedy.
It was the x/y belts SHEESH - Change your belts people after 5k - 5.5K hours
Might was well change the Z belt so all belts are new and no other issue arise
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