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Clogs in MK4. IS? Switching Materials?  

Eminent Member
Clogs in MK4. IS? Switching Materials?


i'm a recent owner of a factory assembled mk4. I have a mk3s+ (kit), and recently got the 4 (less than 2 months). I apologize before hand for the long story... 

It has worked well so far, i don't print extensively, but little and regularly. 
i've also installed the new FW with IS, and new slicer.

I don't know if the two things are related, but after a beautiful 6-hrs print using IS (PLA), i've launched another one and after an hour or so i hear the extruder ticking, and it was clearly not extruding. Stopped the print, I was able to offload the filament, but not to unload new one. With some tinkering and a needle up the nozzle, the clogged cleared. I launched a 1 hr one and went fine. Then another one and after 1/2 hr same thing, ticking and clear underextrusion. Nozzle seemed clogged, and when i inserted the needle (while removing the filament) a big splooch of filament came down. 

Now... I'm not sure where to go from here, and what is happening 🙂


  1. Could this be due to switching from PETG to PLA and viceversa? do i need more cleaning in between? (I got some cleaning filament, and there's another question about that).
  2. When using IS (and appropriate filament profile for it), is it enough, or do i need to get highspeed filaments? I'm trying to understand if using IS and higher speed may be causing these clogs due to the filament not being able to keep up. Maybe stupid question.. not sure.
  3. Lastly: good procedure on how to use the cleaning filament? do i use the usual 'load filament' procedure from screen, or turn off filament sensor for example, and try to manually extrude? (i've seen both suggested online and i'm not sure)

Thank you and sorry for placing multiple questions in one... Right now this is all stuck in my head and i'm not sure how to move forward.

This topic was modified 4 months ago by Mammanta
Posted : 09/10/2023 11:38 pm
Famed Member
RE: Clogs in MK4. IS? Switching Materials?

Going from PETG to PLA I usually load at PETG temperature and run the filament through a few purge cycles. I use cleaning filament after printing with PC, PCCF, ASA etc. Again, I load at the higher temperature and run it through for 5 or 6 purge cycles.


Posted : 10/10/2023 9:20 pm
Eminent Member
Topic starter answered:
RE: Clogs in MK4. IS? Switching Materials?


finally got around to get cleaning filament and taking a look at the machine (I needed a break…).

I’ve used petg temps and done several rounds with the cleaning filament. At first it was coming down thinly but with some extra help from a needle, the flow was def bigger.

BUT, and here my question, it still curls up quite some up at the nozzle. I thought this could be sign of partial clog…?

what would you advise..? The cold pull on mk4 seems more complicated but I could try that, or maybe the nozzle is fine now..?

thank you 🙂

Posted : 16/10/2023 5:25 pm
Illustrious Member

It sounds like you had some PETG residue somewhere in the hotend that has cooked solid over time and dislodged into the narrowing of the nozzle - cold pulls are likely to be the answer.


Posted : 17/10/2023 12:36 am