The join between the hotend and the heat sink is leaking. I have recently replaced the hotend due to this exact issue and it happened again. I probably did something wrong when reassembling it. You can look at the photos attached.
Is the small length of boden tube still between the extruder and hotend? did you replace that, if so it needs to be the exact length
That is the flaw with the first two versions of the K1 series hotends; the nozzle heatbreak interface tends to expand slowly during use.
Creality’s fix is the unicorn nozzle setup; there is an upgrade kit.
K1 Series Ceramic Heating Block Kit—Quick-swap Nozzle Kit for K1/k1 max/k1 C
Most, like me, have switched to the MicroSwiss Flowtech setup. I have never had any issues with filament leaking, and I have changed over both my K1s.
Currently, the Flowtech doesn’t work on the latest version of the Creality heatsink without modifying the heatsink; if you have this one, then the Flowtech is not a direct drop-in.
Creality Unicorn and MicroSwiss Flowtech nozzles can be cold-swapped (no heat-up required). The Flowtech’s benefit over the Unicorn is that MicroSwiss has more types (wear resistance plated brass, CM2 harden, Diamondback, and CHT high flow) and nozzle sizes (ranging from 0.1 to 1.0 mm) and is adding more as time goes on.
Despite minor changes between the heat sink versions, the mounting holes are all the same (I know I have upgraded my two K1s through all versions of the heatsinks).
As I have them labeled:
In versions 1 & 2, the five parts are individual parts: Nozzle, heater, heatbreak, and blue PTFE tube between the heatbreak and the bottom of the extruder. Versions 1 to 2 heatsinks have some improvements to the cooling airflow. Half of the heatbreak and PTFE tube is within the heatsink.
Version 3 & 4 heatsinks the three parts are individual parts.
Unicorn (nozzle-heatbreak-metal tube), heater, heatsink. Version 3 has improved airflow over V1&2. Version 4 has improved heat transfer (silver fins are copper coated with, I think, nickel); black parts are structurally not cooling since they only contact the silver part are two screw mounts at the top.
If you are talking about changing to the unicorn.
Nope, your version has a 6mm hole for the heatbreak; the unicorn heatbreak is only 5mm, so there will be no contact between the heatbreak and the heatsink, hello heat creep, and jams.
Ok so I should just buy a replacement kit that comes with the heatsink, ceramic heater and unicorn nozzle like this https://www.aliexpress.com/item/1005007581941132.html
Ok, thanks but I think I might as well upgrade the whole hotend while I’m at it.
I didn’t think you could upgrade the K1 to the unicorn nozzle without swapping the hot end, it would greatly surprise me if that worked!
Here’s the Creality upgrade kit for the K1
I wasn’t sure about that either until I saw Creality Kevin’s video that he did:
If I were replacing the hot end, I’d certainly have gone for the unicorn nozzle! I think that was a major improvement, and there’s virtually no chance of internal filament leaks like you see so many pictures here.
Is the small length of boden tube still between the extruder and hotend? did you replace that, if so it needs to be the exact length
Yes it was still there before I upgraded it
