Filament stuck inside Printer Core / Can't remove Bowden tube

[BriRMC 0]

Hi all,

 

I'm working at a college where we have 2 Ultimaker 3's. I've ran into an issue with one of them today that I'm unable to solve by myself / Googling and I hope someone here can help me with it.

 

I was running a print with both cores: on Core #1, it's a AA 0.4 with a white PLA filament; on Core #2, it's a BB 0.4 with a transparent PVA filament.

 

Sometime during the print, the PVA filament broke and got stuck inside the Bowden tube, and I haven't been able to unload the PVA filament that's stuck inside. The PLA filament from Core #1 was unloaded without any issue, and I was able to remove and reinsert the core. But I'm unable to remove Core #2 nor unload the filament or the Bowden tube.

 

I've tried reheating the #2 Core to remove the Bowden tube, but it seems like it's really stuck..

 

What could I do to solve this?

 

Thank you in advance.

[Carla_Birch 116]

Do you have anything like a craft knife that could fit in the gap and let you cut the filament where it enters the printcore?

 

You could then remove the bowden and remove the broken filament from it and then try running the print core cleaning to see if you can unblock the print core, you might need to also get some nozzle cleaners the right size of the nozzle and try pushing them up the nozzle when hot from the underside to help unblock the print core.

Edited January 28, 2022 by Carla_Birch

[BriRMC 0]

6 hours ago, Carla_Birch said:

Do you have anything like a craft knife that could fit in the gap and let you cut the filament where it enters the printcore?

 

You could then remove the bowden and remove the broken filament from it and then try running the print core cleaning to see if you can unblock the print core, you might need to also get some nozzle cleaners the right size of the nozzle and try pushing them up the nozzle when hot from the underside to help unblock the print core.

 

We have a few small scalpel knives that I can try using to cut the intersection between the filament and print core.

 

I'll try removing the Bowden after that and will update here.

 

Thanks Carla!

[BriRMC 0]

Just wanted to update: 
I tried cutting the filament with the scalpel but it's too thick to cut through. I tried also loading another material behind the stuck one to see if it'll push out while extruding, but that didn't work either (the second filament never got pulled in).

 

At this point, I have no idea how to proceed on this.

[gr5 2,268]

So I fixed this using an exacto knife that I had heated to a high temperature with a flame.  The problem is the knife is very thin and doesn't store much heat so I had to heat it a few times (I think only twice?  maybe 3 times) but I also had to remove the knife before it got stuck.  And you have to just guess if it's still warm enough or time to remove.

 

Also you have to be careful not to damage the white plastic head.

 

It all sounds difficult but it took all of 30 seconds.

 

[BriRMC 0]

So we ended up solving this with a tad bit of brute force.

I first disassembled the printer head (remove the 4 screws on the top and unplugged the white "power cord")

Then I clicked the side claw (the little lever on the side of the printer head) to have the BB core rise up and push the filament out, and finally we just brute-force pulled the filament out of the core.

 

I'm going to try to clean the core as best as I can before I reinsert and get back to using it.

 

Cleaning the Bowden tube wasn't too hard either, just had to disassemble it completely first, which was a bit tedious (had to unscrew the feeder on the back and put it back together after.

 

I think everything should be fixed; I'll update here later with my results.

[gr5 2,268]

You shouldn't have to unscrew anything on the feeder.  The bowden comes off on both ends and you can use another piece of filament to push existing filament through the bowden if you can't reach any of the filament.  Also if you lift the arm on the feeders now you can just easily slide filament through the feeders.