SOLVED Brand new BB core clogged

[Hero_s 0]

Hi again, I wrote this post not so long ago

https://ultimaker.com/en/community/51243-super-clogged-printcore?page=last

I wasn't able to unclogged it so I got a new BB core and started a print with it. At first, everything went well but it stopped halfway. You can see the first layer and how I found my print the next morning.

The PVA filament got stuck in the feeder and stopped extruding. This is how it looked like:

I cleaned the feeder and tried to start my print again, but then the nozzle jammed. I tried the atomic method to unclogged it at 260 °C. At first, the filament came out of the nozzle looking like this:

Then, nothing would come out of the nozzle and it seems to be ultra-super-clogged again, even though it's the printcore's first print. I suspect that the filament's old age is responsible for all my troubles, so I opened up a new PVA package of filament and it was much more stiffed than the old one. The tip of the filament used for the many tries of the atomic method all look like this, they don't seem to reach the hot part of the printcore:

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As suggested in the previous post, I tried to leave the printcore at a temperature of 225°C for the filament to melt and come out, but it did nothing. Except it maybe «cooked» it even more. I really don't know. I guess the next step will be the needle. I got one from the drugstore, but the only one tiny enough to fit it wasn't very strong and broke when I tried to insert it.

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SO:

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Could the age of the filament be the problem?

At what temperature should the atomic method be done for PVA?

Could it be a possible solution to just add some drops of water in the pipe to «melt» the PVA inside?

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BONUS: my print was also glued to the buildplate. I put it in the freezer and was able to get it off. At least, something I did worked...

[rebekah_harper 60]

age could be a factor if it's got moisture in it.

PVA will go powdery at high temperatures. so I think the 260 was not a good idea. in the maintenance part of the menu there is the hot and cold pull. I recommend you use that. at least you can blame Ultimaker.

I use PLA for the hot and cold pull.

insert and use pliers to force it through. if nothing comes out use a strand from a wire brush and poke the nozzle. I think you'll be a while doing it again and again.

I sometimes vigourously move the PLA in and out the extruder (2 or 3 times) then press hard and yank out.

do this a couple of times and then cold pull as per the machine's direction. then do the hot pull again. you'll have to do this quite a few time unless you get this.

Please take your time and do this a lot. even if it looks like its free flowing, keep doing it cause there should be a lot of brown PVA in there. +- 10mm of the nozzle worth.

I don't think the problem is the feeder but a consequence.

Please use this Reel casing

this is until I make and test a new and better one.

hope you manage to sort it out. it isn't lost just needs patience and time spent on clearing the blockage.

Rebekah Anderson

[Hero_s 0]

Hi again, I FINALLY MANAGED TO UNCLOG THE PRINTCORE.

(multiple celebration emojis here)

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I began with hot and cold pulls with PLA at 230°C and needle poking through the nozzle and somehow, a brownish mixture came out of the nozzle. Just a bit, but it was enough to give me some king of hope. I kept doing it with a piece of blue PLA to see if the color would flow through the nozzle. Here's how it looked like:

I switched between a blue and a yellow piece of filament to see if it was getting any better. As you suggested, I «vigourously move the PLA in and out the extruder (2 or 3 times) then press hard and yank out.» Eventually, that combined with the hot and the cold pulls, chunks of burnt PVA began to stick to the PLA. This is the biggest one:

I finally just kept the nozzle's temperature at 230°C and kept applying pressure with a piece of PLA filament at the top and the needle poking the end whenever nothing came out. A bit like this:

After 3h of trying plus everything I did before my post, the printcore was finally free. Here's a look of the some tips of filament I used:

I would say the the most helpful part was applying pressure at the top and sticking the needle whenever nothing came out. I got them at the local drugstore, they're used for insulin injections.

And that how it ends, I hope.

[rebekah_harper 60]

Hiya,

pretty much my story too. took ages although I used a strand from my wire brush to poke.

but I am glad to see you got somewhere. if you put your build plate to 40 deg and place your PVA on some card board and put it inside. if you haven't got an enclosure I would consider covering the machine with a towel for an hour. then make a setup similar to mine or even print off the reel cover and add a tube then put it all in a sealed bag. you will find it will be fine.

just every couple of prints, do a hot/cold pull.

aim is to minimise the exposure to the air and keeping the core clean. I have had mine for 3 weeks and not one blockage.