Printer completely stopped printing TPU after 1 year and a half.

Flagship K Series Creality Flagship K1 Max
1

Just what the title says. I bought a K1 max in november 2023 and it has been perfect, up until now. about 2 weeks ago my printer randomly stopped printing TPU entirely.

I have been printing PLA, TPU and nylon interchangeably for its entire life. I printed some TPU parts about 2 weeks ago without issue. The printer sat idle for 2 days as it often does. And then it largely stopped being able to print TPU. It started by printing 6 or so layers and then hard stop, no signs of under extrusion, just a hard stop of filament flow and printing air. Then it just stopped printing TPU altogether. It currently doesnt even load, it just skips like the extruder tension or feed is incorrect. I tried replacign the hot end. I tried replacing the extruder. I tried reflashign the firmware.

Im just baffled at how a filament and settings and machine that had been working perfectly for a year, including off the same roll, stopped working almost entirely 1 day to the next. ANY ideas are welcome because im just lost.

3

I take it that your TPU is thoroughly dried? Extruder skipping could be something caught in the extruder, need to have it apart to examine it.

4

Both dried rolls and fresh rolls.

Extruder has not only ben taken apart and inspected but replaced outright with a new one

5

Next to try:

  1. Check cable connections from the tool headboard to the mainboard and cable power.
  2. Check for voltage drop on tool board power wires while powered, measure across; ground at the end of the electronics bay to the same at the tool board. Move the tool head around the x&y to see if any voltage above 0.5 volts. Replete on the positive wire. Bad cable if shows above 0.5V drop.
  3. Replace the stepper motor for the extruder. If doesn’t fix then on to 4.
  4. Replace the tool head boards. Might be the TMC driver for the extruder.
6

Its just TPU you are having issues with, you can still print PLA/PETG without problems?

7

Yes. Hard filaments have seemingly no issue at all. TPU behaves like theres a nozzle clog. I can occasionally get it to extrude normally when loading. When I do and I start a print, it stops extruding after a few layers. After which it will nto extrude at all. Other times I go to load the filament and it just will not load.

The thing I have the most problem with, is that it started virtually overnight, with a filament and settings ive been using for over a year with no issue at all, a roll of which I was midway through after only a day or two idle. The on/off nature makes me think somethign broke, but ive replaced most of the head at this point.

8

Might want to check the print speed/temp settings in the slicer.
Some things need to be revealed, did you switch it over to the unicorn nozzle with the newer extruder, do you use a top mounted spool and print with lid off and door open?