I had a PETg Filament (non bambu) that was always printing fine but never great. I decided it was time to change that and made a calibration. To make the calibration usable by other roles of the same filament I dried it with the sunlu S4 on petg settings for 6 hours.
First I successfully calibrated my flow dynamics to 0.35. The flow rate calibration however was unusable. All of them look awful so I stopped there. I double checked that petg was selected under devices. All other settings are default for my p1s. If I print a normal surface it comes out in unconnected stripes so under extrusion?
The filament recommends temperatures between 250 and 270 °C. I think the bambu default is 255°C. I could manually start changing the flow rate but I don’t really know in what direction and by what increments.
Any tips on what to change and where to investigate would be greatly appreciated. Other petg is printing fine and the calibration also works for them. The strange thing is: before drying everything was working. I got a couple more rolls of that filament.
Did you try the other filaments after this print job? To me it looks like severe under extrusion. My first guess would be some kind of contamination while drying it, so now your nozzle is partially clogged. But obviously that wouldn’t be the case if other filament still prints without problems.
Thank you for your reply. Yes I printed other filament after that and it went great but I will double check and try to clean the nozzle and print again with some other filament. Really looks like severe under extrusion. This is so strange
I started from the idea of under extrusion and increased my flow rate manually and printed test cubes 20x20x1 in mm. My prints where getting better to a point wher overextrusion started happening but the filament from the inside was still not connected to the walls. I then concluded that flow rate was not the problem and started tweeking the only other parameter I knew (flow dynamics) I did a second calibration but got no new results. It always looked like 0.3 0.35 to me. As it was getting worse with increasing numbers I thought I try a smaller number and just see what will happen. Indeed the problem and the gap to the walls became smaller. I decreased it multiple times until I settled at 0.05. Keep in mind that petg default is 0.4 and the calibration gave me 0.35. But it worked and now I get some usable results from the flow rate calibration. The drying must have completely changed flow dynamics.
Moisture level in filament can do that. What’s worse is when drying is only partially effective to where drying completeness depends on ambient humidity. Inconsistent drying can cause inconsistent filament behavior and inconsistent quality in prints.
Are you sure that 0.4 is default? that is missing one 0 in my opinion. Even for TPU 95 HF, I only use 0.24. For PLA my calibrations are in range 0.017 to 0.020, for PETG, I have filament between 0.023 and 0.041.
Yea I double checked. It’s 0.04. But with that little of a difference I am wondering why it completely messed up my first print before the calibration that was at defaults. But flow rate will definitely be something I will keep an eye on and won’t underestimate again. Nor will I completely trust the default bambu calibration again.
