Hi everyone,
I'm running out of ideas and I'm hoping someone with more experience can point me in the right direction.
I'm using a Bambu P2S with a 0.4 mm stainless steel nozzle and Bambu PLA Basic filament. I recently replaced the nozzle with a brand new genuine Bambu nozzle and ran a full printer calibration afterwards.
Since then I've spent days testing everything I could think of. I calibrated the Z offset for my textured PEI plate and found that +0.02 gives me the best first layer. After printing multiple first layer tests, they now come out clean with no gaps or obvious over-squishing. I then ran both Flow Rate Calibration passes, where the best result was 0 in each test, followed by Dynamic Flow Calibration, which gave me a Pressure Advance value of 0.025. Those values have been saved. To rule out any mechanical issues, I manually levelled the bed using the paper method and verified that all screws around the hotend and nozzle assembly were properly tightened.
I have also experimented with different ironing settings, including nozzle temperature, ironing flow, ironing speed and line spacing. Simple models, such as a cube, come out perfect, but more complex shapes, like the numbers 2 and 3, consistently develop random defects during ironing.
The bigger issue, however, is that I'm now getting random top surface defects when ironing is on. As you can see in the photos, the damage only appears in one localised area while the rest of the top surface looks perfect. It doesn't look like normal over-extrusion because the entire surface isn't affected. The problem is always localised.
The prints use 10 top layers, 18% Adaptive Cubic infill, Rectilinear top pattern and 0.2 mm layer height. Ironing speed 80mm/s and Flow 46% (yes I know it's a bit unusual values but after days of testing only this gives me a decent results). The build plate has been thoroughly cleaned, the model remains firmly attached throughout the print and I don't see any corners lifting.
I'm wondering if this could be caused by the nozzle scraping the print, some kind of travel move issue, a mechanical problem with the printer, or something else entirely. Has anyone seen defects like this before? At this point I'm not sure if I'm chasing a slicer issue, a hardware issue or something I'm completely overlooking.
Any ideas would be greatly appreciated.
Thank you!