Purge Line prints but model sticks to nozzle and never adheres

Bambu Lab P1 Series
1

P1S
AMS
PETG (Grey - Bambu)
0.2mm Stainless Nozzle (and I own several other sizes in hardened and stainless)
Stainless Extruder Gear (Also own hardened)
Engineering Plate (Dual-sided with cool plate. Also own textured PEI)

It seems my printing woes just keep getting deeper.

When I got my P1S in October, I printed 70+ models without major issues.

Sometime in November, I started having major issues with stringing and PETG sticking to the nozzle. I had to start babysitting and models regularly failed.

Now, in February, I can no longer get a model to print: The purge lines work just fine, but when the nozzle moves into position to begin printing the model itself, adhesion never even happens. The extruded filament just sticks to the nozzle and, if left unattended, fills up the silicone sock with PETG while dragging a ‘hockey puck’ across the plate. (NOTE: I’ve realized this is only the case with my 0.2mm hotend. 0.4mm is working.)

I’m currently using a 0.2mm stainless nozzle with the hopes of addressing some stringing issues on a 45deg long, straight overhang. (Mentioned a few months back in another post.)

I read a post about PETG requiring a bit more space than other filaments, and so switched from the textured PEI plate to the Engineering plate (fully washed with detergent and slathered with PLA glue from Bambu.) No dice.

I read another post about this issue where reverting firmware fixed the issue. I tried the two next-most-recent firmware updates to no avail. (I don’t really want to go back to last June’s firmware, which would likely be the version that solved the OP’s issue.)

I received a bunch of cereal storage boxes for Xmas and sent all my filament through the oven before sealing it away with plenty of dessicant beads. The PETG I’m currently using was new at Xmas, went through the oven, and has been living in my fully-tricked-out AMS at 10% humidity since then.

Each time this failure occurs, I take off the silicone sock, remove the excess PETG using needlenose pliers, and brush the nozzle exhaustively with a brass brush.

For what its worth, I have also removed the extruder box, buffer, and nozzle, and fully cleaned them out using my electric ‘compressed air’ handheld fan. Like a handheld hurricane.

Despite my efforts, it appears that my success rate continues to nosedive. :frowning:

**UPDATES
**
2022/02/04
I tried a factory reset of the P1S. Did not help.
I was asked about my max volumetric speed for PETG-BASIC. 1mm^3/s (default.)
I note that the dynamic flow calibration files will print, if only partially. This could be due to an issue with my model BUT it is basically a flat rectangular plane, and the print fails before even GETTING to the model itself. It fails on the support bases.
I do wonder whether this is due to my ‘organic tree’ support bases being circular. My printer has always struggled with adhesion when printing circles.
2022/02/05
I abandoned my 0.2mm nozzle for the time being and went back to 0.4mm hardened hotend. No bed adhesion issues with this hotend.

2

Do you have a 2nd new nozzle to compare results with? If you have had a lot of failures, the nozzle may be damaged. Its pretty easy to damage a .2 nozzle if its banging on a print that dislodges.

Edit: I know you said you have others, are they new or all used?

3

This was my first attempt to print with the 0.2mm nozzle. It was new-in box.
There has been no ‘banging’ at all. There has been nothing to obstruct the path of the nozzle as the entire mass has been moving with the nozzle.
I also have a second 0.4mm nozzle that was new in November and has seen very little use. I could try swapping back to that… but the 0.2mm nozzle did this right out of the box.

4

Have you done a flow rate test with the .2 nozzle? Just grasping straws but could be set too high/low in your filament profile? Probably something changed with new bambu studio version or firmware. Might be worth starting there if you havent.

5

I did do a flow rate test. (The ‘Dynamic Flow Rate’ calibration ‘pattern’ test.)
All the lines came out with similar result: only a very slight stringing at the tail end of each Chevron. All stringings were equal… no one Chevron was any better or worse than the others.

I did try two older firmware versions. I suppose if I can’t get relief I’ll load a year-old version to see if it fixes anything… but the two previous versions did not help.

IMG_2904
IMG_29041536×2048 339 KB

<NOTE: This was completed on the Textured PEI plate, before I switched to the Engineering plate.>

6

What is your filaments max volumetric speed set to? Is it too high/low? If its set too high and the nozzle can’t melt fast enough you would have adhesion issues.

1 Like
7

1mm3/s is my PETG-BASIC Max Vol Speed… Default.

image

8

I’m all out of guesses. :frowning:

1 Like
9

I had two unused nozzles:
-0.6mm hardened steel hotend
-0.4mm stainless nozzle

I took the time to swap out the fan on an older used hotend to the new 0.4mm nozzle. Turns out that fan is dead. I’ve ordered a new fan so I can get all my nozzles into complete hotends.

I may try my luck with the 0.6mm tomorrow, or just wait for the new fan.

10

I went back to my (used) 0.4mm hardened steel nozzle. No adhesion issues.