Hi,
I’ve recently bought two Bambu Lab P1S printers and am having the same issue on both machines (please see photos). I’ve spent a while reading through forums, but can’t work out if this is likely layer shifting or something else. It seems to occur in taller prints, but I never used to get such a bad effect on my old Ender 3s. A few quick details:
- This is using Bambu Basic PLA, but the same thing has happened with third-party PLA.
- I’ve got a 16x16x1" paving slab under the printer on a washing machine vibration mat.
- I’ve been printing on normal speed using 0.12mm fine mode, but once I shifted to silent mode mid-print and the lines got worse (as you can see in the photo from printer 1)
- On the print on Printer 1 I used printer glue to bond to the surface and on Printer 2 I used a brim so presumably they should have been pretty well stuck to the bed.
- I have two printers that were purchased July and August and they’re both doing the same thing.
- I’ve just noticed that there seems to be the same 22mm between the major defect lines towards the top of both prints on both printers. I’ve no idea if this is coincidence!
If anyone has any clue what might be causing this and any potential solutions I’d be really grateful.
Many thanks!
When asking for help, please provide as much information as possible about your inquiry.
This will help everyone to better understand your problem, and provide you with the best solution.
- Detailed description of the problem
- Printer model used
- Slicer settings used
- Type of filament used
- Photos that clearly show the problem
- .3mf file (if the file can be shared)
- Any potentially useful information that is related to the problem
This is not a complete list of all possible causes for this, but maybe it puts you in the right direction.
It is not layer shift. That would show up as misalignment of the layers on top of each other wich this is not.
What you have here can be caused by several things:
- Speed differences: As the speed of the printhead changes the shrinkage of the plastic can change in relation to other parts of the print creating this kind of lines. Check the speed preview and see if the lines you see on the print correspond with speed changes in the preview.
- Model geometry: Depending on the model geometry the speed can change, see above. Also it looks like you have a tall slim model. That might start flexing under load of the printhead making it move and creating lines that way. This would be consistent with the lines getting worde to the top of the print.
- Filament humidity: If the filament is wet it can ooze out while the printhead is traveling. The amount of plastic layed down by the printhead can change because of that, creating lines. Dry your filament.
- Filament diameter: The printer assumes the filament diameter is constant. In practice this is never the case, causing slight variations and lines. Check your filament to see if it has obvious bumps or thicker parts (I have hade this in the past with a roll of ABS)
Hope this helps a little…
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Thanks so much for the advice! I think you’ve put me on the right path for the problem! I’ve attached an image of some speed changes and a geometry change which are consistent with the lines at these heights. This also seems to make sense for the print on the other printer.
I also have nearly finished printing a test piece of a straight long column and it doesn’t show any issues with lines so that shows tall prints seem ok without these speed changes.
Since this is a new problem for me, I’m going to need to try and see if there’s a solution out there that will help reduce the issue. I don’t suppose there is a name for this problem so I can start to investigate? Many thanks again for getting me on the right path.
Hey there, 1st of all try to reduce the acceleration if its possible go less to under 1000mm/s², 500 for example and deactive Input shaper or whatever the Bambu Name is.
Also try to rise the Temperature 10 degrees 
In this high and Mass the Work piece can get its own frequencys and that would Look Like that
Many thanks! Do you mean acceleration for outer walls? I can see I the Acceleration tab the following numbers:
Normal - 10,000
Initial layer - 500
Outer wall - 5000
Inner wall - 0
Top Surface - 2000
Sparse Infill - 100%
I’ll have a look into where the input shaper is.
Many thanks!
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Do outer walls and Normal down maybe 1000 or 500 Like the Initial.
To Unterstand what Happens.
The Input shaper or whatever Bambu ist calling it (in the printer setting Not the slicer. I think) sinulates a Vibration in exact negation to the real Vibration.
Because youre build isb very tall, IT can Swing delayed so the negative Vibration Doesnt Match theb real Vibration.
Without high acceleration there would be much less Vibration.
Butni could be wrong also. ITS Just am Idea good lucl
Many thanks! I will give that a try and let you know!
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hm… need help as well… i recently bought a P1S just few weeks ago… when i tried printing a lego head using PLA (regardless of color), i always get these 3 lines protruding… i really dont know why. m still a noob in 3d printing.
Those are the seams, see this wiki for everything you need to know.
Seams
You can manually “paint” where you want them to be, perhaps the back of the head?
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thanks! will read up on it… very much appreciated!
hm… just read up about the SEAMS… for a cylindrical lego head… it would seem hard to hide the SEAMS then… i am not good at sanding and painting… was hoping to leave the prints as is. now have to find a place where to conceal the seam =(
There are many ways to hide seams. Orca git a Feature to Put them INSIDE. More retraction could also Help. Try to Print the outer walls 1st
