I’m trying to print a piece with my Bambu Lab PS1, and I keep encountering the same issue: a strange line appears on the exterior.
It seems to align with the internal flat surface of the piece, but I don’t know why this is happening.
Could someone help me out?
Thank you very much!
Welcome to the community, and thank you for posting clear photos. This helps the community help you tremendously.
The TL;DR version of this is to try to change the default wall order from inner/outer to outer/inner. Also, increase your wall loop by 1 wall or more. This will lay down the outer wall first and the inner wall second.
This type of anomaly can be caused by a number of factors but I’d wager that the underlying model structure is influencing the rate at which walls are shrinking after the molten filament has been deposited.
If you look at your photos and look at the model, the lines appear to coincide with this structure in this image highlighted by the green arrow.
What is likely happening is that underneath the model, there is a change in internal structure which creates a density difference in the way the filament is laid down. If that difference is great enough, one part of the model may shrink differently than the other or as it appears in your case, lines are being extruded at a different rate. Please note one option is to manually tune the filament profile and get the slicer to do more work on your behalf. for this type of extrusion error, I would use Orca Slicer, not Bambu Studio and use their baked-in max flow rate calibration utility. Alternatively, you could simply slow the filament feed down in the speed menu via trial and error or use the silent mode print feature which will slow all movements down by 50%.
What would be helpful is if you can post an image of the sliced model at the sections that are affected so that we can see what’s going on behind the layers. If I’m guessing correctly, based on one of the images, you have access to the original cad model. If you could perhaps post a x-ray or wireframe rendering, this may also reveal what is going on.
Here’s an example of what I mean by a CAD model having underlying structures that the slicer sees but not necessarily visible on the model surface.
Note that when we look at it under the sliced screen and move the slider down to layer 30 in this example, we can see that these two structures are treated differently internally, and filament is laid down at different densities. In this example, I exaggerated the effect by changing the wall numbers and pattern for the cylinder, so it was easier to see.
If I look at it using CAD as a solid(the view your example is using) vs a wire frame, this is what it looks like which is why I was asking for the additional screengrabs as this would tell us more about the model structure itself.
First of all, thanks a lot for your quick an extense answer.
I have already tried the 2 first options you have sent me:
I have wall loops set at 5 and Outer/inner selected
Here you have more pictures of the model. Taking a look closely it appears the line is aligned with this surface:
And here you have some more pictures:
Don´t know anything about Orca, but if you can tell me more about this option you said it has, I can try that too.
Hope this can help
Thanks a lot for your help and your time.
Orca Slicer is a fork of the Bambu Studio source code so you would be forgiven if you loaded it and mistakenly mistook it for the same software. But under the hood there are a number of quality of life enhancements the first and foremost are detailed calibration utilities baked into the code. This tool is indispensable, albeit time consuming when troubleshooting filament behavior. You can operate both slicers on the same machine so there is no downside to using both.
I generally refer folks to these two video for a general introduction. There are other videos out there but I believe this one YouTuber covers the basics.
Here’s the download URL
Maybe this can help too:
I think everything starts here, with this first blue fill layer for the surface I tald you in the previoust post
Thank you for the additional GIF and detailed slice. I wish more people would provide this level of detail it just makes interpretation so much easier. The animated GIF reinforces the notion that the artifact appears to be happening at the transition boundary noted previously here:
I see that you already took the route of creating a test section. That’s great. But what I can’t tell from this photo, it looks like the problem didn’t present itself in the test section? Am I interpreting this correctly? It may help to cut out a test section that includes the full height of the model for comparison purposes.
Alternatively, if you have Access to the CAD model and can tinker with the design, you could add a structure below the section heer eliminating that bend in the model.
One question I don’t think I asked or was offered, does this happen with other filaments?
If you feel comfortable uploading the 3MF file, I’d be happy to examine it in more detail or perhaps test print it on my P1. If you don’t wish to do that on this thread, then you also have the option of messaging me in this forum and uploading it that way where I will be the only one to see it.
** Edit – I should also add, if you have the STEP file, that will allow for more granular analysis.
