Extruder knife keeps getting stuck for no apparent reason

Flagship K Series Creality Flagship K2 Pro & K2
1

Heyo first time poster here :waving_hand:

I got my K2 in November last year and printed about 10 projects so far, with little struggles and experiments along the way. So far so normal.

But since a while now the extruder knife keeps being stuck when I want to start a new project/try to extrude a filament.

Now I tried disassembling the extruder part, looking for loose filament, exchanging the nozzle, exchanging the knife part, even turning the knife upside down, putting some grease on it, tightening the screws and even leaving the screws a bit loose, since the knife is moving with no problem when the extruder part is taken off the nozzle head. It gets stuck when the head slams into the ‘knife stick’ on the side of the printer, and when I loosen the screws and lift the part off the back a bit it ‘snaps’ back into position.

Now I ran out of Ideas what else I could try, since there are no moving parts in that area, except the knife itself.

May this be a broken Magnet?

Best regards,

Johannes

2

Have you tired switch the orientation of cutter? Its could be magnet being applied incorrectly, causing it not rebound back.

3

Give it a very light polish, not sanding but polishing. Is the blade still fine? No dents? Using a little spray on the part helps, not grease but fine silicone spray. Creality recommends using only WD-40 Specialist Silicone. Check this maintenance video. https://www.youtube.com/watch?v=jPEQ3dxhWY4 and this one to find out about the best lub K2 Plus Idler Wheel Noise Lubrication Guide | Creality Wiki

4

Yes, I tried that. I even tried the spare knife that was delivered with the printer and tried it upside down :woman_shrugging:

5

Well, I didn’t try polishing it since I don’t think that friction is the issue primarily. As I said it slides in and out with no problem as long as the extruder is not put into place. And I used the word grease but I ment lubricant. I didn’t try silicone spray I might try that but again I’m confident it’s not a frictional issue

6

Many people are complaining that the magnet on the cutter comes out all the time. Are you sure the magnet is still there? Check this Creality official video. https://www.youtube.com/watch?v=c0EKlBXRflk

7

Got the same problem: cutter works fine when extruder is disassembled. With extruder assembled cutter sticks in cutting position.
What worked for me: loosen the nozzle a tiny bit released the cutter and now its working fine again.
Dont know what caused this in the first place thought :-/

8

Yeah I tried something in the likes to this already, didn’t work for me tho.. Do you mind explaining what exactly the process was that lead to this success?

9

Absolutely positive. As I said. When I take the part off (the one where the gears and the cutter is in) the cutter slides and snaps back as intended. It’s only a problem when it’s back in the operating configuration when it gets stuck

1 Like
10

In my case I did loosen the nozzle a bit and the cutter worked again.
See Replace K2 Plus Nozzle | Creality Wiki
Step 4. Use a straight socket wrench to unscrew the old nozzle
I just did this, loosen the nozzle maybe some 1-2mm and the cutter worked again.

11

Faaaken hell dude that fixed the problem. Thank you very much. Where are you from man?

12

Glad it worked for you - this printer has become a tinker project for me the last weeks after working stable for over a year. I am from Germany