SOLVED Super clogged printcore

[Hero_s 0]

Hi, the BB core of our ultimaker 3 extended seems to be clogged very badly. I have tried repeatedly the atomic method to solve the problem, but it never worked. The filament won't come out of the nozzle. I took a look inside the nozzle for a better understanding of the situation and as I can see, there seems to be a huge chunk of melted filament in the way.

I haven't tried the needle option yet, because I don't own such a needle, but it should be the next step. Still I don't have much hope for that solution because of the state of the nozzle.

Does anyone already had that problem before? Is it a common situation?

[Brulti 177]

I had a similar problem not too long ago. I managed to solve the problem by warming up the printcore for quite a long time, maybe half an hour, at the upper range of temperature for the filament stuck inside.

At some point, it melted enough to start seeping out, forming like a liquid drop around the lower part of the printcore. Then I did several hot pull, pushing hard to force the stuck filament out, melting it little by little until it gave up at some point, I felt it, and then I did several hot pulls and cold pulls until the printcore was clean.

I used filament of a different color for the hot pull, so I could see at which point what was being extruded was no longer the stuck filament but the one I used for the cleaning. Hope this helps.

[kmanstudios 1,120]

I have had to use an airbrush needle sometimes to get the main clog out and then use a bit of a 'pumping or plunging' action on the cleaning filament to get to break stuff loose.

Be careful sticking something in there as you can flare out the nozzle ends if you are not careful or scratch the interior making it grab the plastics much more later on.

[rebekah_harper 60]

Hiya,

the BB core has this issue due to the PVA and it's moisture hate relationship.

with the moisture it starts to create a lining inside the core. this gets to a point where it's about 1mm diameter hole

I uploaded a solution to the problem. a spool casing that holds silica gel packets and it can be put into a bag.

what they missed is that if you print as much as we do, there is no opertunity to change the spool over with another PVA whilst you dry out the used one and print with the new one and do that for nearly every print. this isn't really practical. so for the UM 3, it's not an industrial standard with PVA printing. they should have considered encasing the PVA spool within the printer frame with either a heat element or silica gel pocket to place the packets in.

I can imagine that either a UM3+ or UM4 will incorporate some controlled environment for the PVA spool otherwise on it's own it fails as a heavy user printer with PVA in mind.

Sorry ultimaker but unless I missed something I believe this to be the biggest flaw.

having said this I still love mine to bits.

Bex

[Hero_s 0]

Thank you a lot for your replies, unfortunately I wasn't able to unclog the core so I bought another one to replace it...

I'll be aware of the moisture problem next time.

[Hero_s 0]

I finally solved the problem and here's how I did it:

https://ultimaker.com/en/community/51531-brand-new-bb-core-clogged?page=1&sort=#reply-190879

[Fred804 0]

This thread was all from fall 2017, but in case anyone happens upon it, I figure I'll add my story.  I was using dried PVA but got the same problem.  I kept trying hot and cold pulls and reaming up the nozzle with a 0.4mm drill.  Lightly using a 2.5mm drill from the top and the small drill from the bottom had me stymied how there was still a clog. I encountered no resistance on the drill through the extruder but could never print.  I ended up disassembling the printcore (while waiting for a replacement printcore to arrive) and soaked the nozzle, by itself, in boiling water. After awhile, the small drill through the extruder was able to push the clog up and out of the extruder.  My guess is that every time I tried reaming the nozzle previously, it was dislodging the clog up further into the assembly, only to be pushed back into being a clog when trying to print again.  Of course, it's a very delicate thing as the section of barrel connecting the heater block to the heat sink is extremely thin, but it all worked, and I'd like to say that that printcore is working better than most of mine that are a few years old.

[Dustin 175]

While you can use PLA for print core cleaning.. 
I have seen better results myself with using cleaning filament from UltiMaker...

That's not an up sell I gain nothing from anyone buying it.. 
In my personal experience it has yielded better results when I had clogged core that didn't want to clear.