Good afternoon! Can anyone help me out?

I have a Bambu P1S and I'm seeing some strange lines appearing on my prints. This is happening mostly when using a generic silk filament from a reputable Brazilian manufacturer.

You can see the lines in the attached photos. I first noticed them when printing the container in the photo—it came out with very pronounced marks. Then I printed a cylindrical part for a side spool holder, and the same kind of marks showed up again.

To investigate, I did some tests with varying speed and temperature using cylinders and a cube to see if I could figure out what might be going on.

I printed two identical cylinders on the same plate, alternating layers between them. One was printed at 60mm/s and the other at 200mm/s. Both had temperature gradients from 220°C down to 205°C (like the Orca slicer temp tower test). Interestingly, the marks appeared on the same layer in both prints—regardless of the speed. (The marks don’t line up with the areas where temperature changes.)

I also printed a cube at a fixed speed (60mm/s, based on the cylinder test) with temperatures ranging from 190°C to 220°C, and this one didn’t show the same marks.

I’ve gone through the printer and done some maintenance—tightened the XY belts, lubricated the rods, greased the lead screws, and cleaned the carbon rods. After all that, I repeated the test but still got the same results.

Then I tested with regular PLA and velvet PLA (from the same manufacturer as the silk), and neither showed these marks—at least not visibly. Maybe the shiny finish of the silk filament just makes imperfections more noticeable?

So now I’m wondering: could there be something wrong with the printer (maybe a calibration issue?), or is it just something related to this particular filament?

Thanks in advance to anyone who can help! I'm still new to the 3D printing world hahaha



Help! Lines in cylinder print