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Karam

Clogged BB Core

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Hi,

My U3 BB core is clogged.

I have only used it with PVA however have not used it for around 1 month.

I suspect moisture has gotten into the PVA material contributing to the clog.

I have tried the two cleaning cleaning methods (Atomic Method and cold) numerously however it does not budge. Its still clogged.

During the Atomic method the temp PLA material comes out clean (no burn marks)

Can someone please provide advise on how to remedy the clog.

Regards

Karam

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There are many ways to clean this. The hot/cold pulls method I hear works best but I haven't had to unclog a UM3 nozzle yet (just um2 nozzles so far).  Also consider contacting your reseller as most of them have probably dealt with this.

As a last resort you can take it apart.  Cores are delicate and it's TRIVIAL to destroy it if you try to take it apart. Just loosening the first screw will often destroy it. I have taken many cores apart so that is very easy for me --  so if I couldn't get hot/cold pulls to work I would take it all apart and soak the nozzle in water for 24 hours.

arrgg!!  I forgot - I can't post this video because it has a "8" followed by a "D" in the url and this forum can't handle that.  Search youtube instead for "um3 ultimaker 3 core disassembly". That explains in detail how not to destroy your core yet still take it apart.

But again - last resort - because once you take it apart you won't be able to get reseller support for that core and I'm pretty sure it violates the core's warranty.

Edited by Guest

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I'm sorry to hear your nozzle is clogged. Maybe we can help you solve the problem here on the forum, and/or you can contact your reseller.

Please don't disassemble the core yourself. At UM HQ we have never had a print core that could not be cleaned without disassembly.

What do you mean with "During the Atomic method the temp PLA material comes out clean (no burn marks)"? You mean that you are able to extrude PLA when the nozzle is hot? That is good, at least it's not completely clogged then.

But what exactly goes wrong during the cold pull?

And what do you mean with that you used 2 different methods Atomic and cold? Cold pull and Atomic method are the same I think?

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I'm sorry to hear your nozzle is clogged. Maybe we can help you solve the problem here on the forum, and/or you can contact your reseller.

Please don't disassemble the core yourself. At UM HQ we have never had a print core that could not be cleaned without disassembly.

What do you mean with "During the Atomic method the temp PLA material comes out clean (no burn marks)"? You mean that you are able to extrude PLA when the nozzle is hot? That is good, at least it's not completely clogged then.

But what exactly goes wrong during the cold pull?

And what do you mean with that you used 2 different methods Atomic and cold? Cold pull and Atomic method are the same I think?

Hi

Thanks for the reply.

I have not disasembled the bb core.

In my original message i meant to say that i tried both the "hot pull" and the "cold pull" methods to clean the bb core with no success.

If you refer the ultimakr website for instructions on the "hot pull" method, you will see item 6 has two pictures. First a dirty pla filament and second a clean one. The point im making is that even when trying the hot pull and cold pull methods the pla material remains clean (second picture). And no, it does not extrude pla material , it is significantly clogges.

Do you have any other suggestions for unclogging my bb core?

Thanks.

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When you take out the PLA during hot-pull, is the tip melted? That is hugely important. If you have material stuck in your cold zone the hot and cold pulls will never work.

If you have placed the print head in one of the front corners like described in step 1, you can put a large force on the PLA. (Use pliers, because when the PLA breaks you will cut your hand). Just press very hard. That may help to press out the clogged material. If there is still no flow, raise the temperature to 275degC.

If that still does not work, there are 2 more options:

1) Use a needle (injection needle, or acupuncture needle) to puncture the clog (just take care not to damage the relatively soft brass)

2) use polycarbonate for the hot and cold pulls (use 270 and 135degC)

Edited by Guest

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1) Use a needle (injection needle, or acupuncture needle) to puncture the clog (just take care not to damage the relatively soft brass)

2) use polycarbonate for the hot and cold pulls (use 270 and 135degC)

 

I have had to resort to this. I held off suggesting the needle because I had a fine tipped Airbrush needle, but not everyone has this.

Also, I have had to do both methods (Needle and PC pulls) just to get my core working again. Now, I clean religiously to prevent this from happening.

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Well if you don't want to take it apart then get a needle that fits into the opening - for example a hypodermic needle or an acupuncture needle that is around .35mm in diameter. Do the cold pull where you heat nozzle to about 150C (don't let PVA stay above 120C for more than a few minutes at a time - if you leave it at 200C for 10 minutes it will bake into a tight clog).

Anyway heat it up and try to get the needle through the hole from below. If you can do that then stick some filament in from above. PVA will work. Nylon is better. Then cool the head to 90C while pushing down from above on the filament and pushing up with the needle. As it gets below about 110C you can remove the needle or just leave it in there.

When it is at 90C lift up with about 5kg of force. If it doesn't come out, heat to 95C and try again. Then try again at 105C, 110C, 115C until it finally comes out. It should be in the shape of the tip of the nozzle.

Check to see if it's fixed and if not repeat.

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HI Guys,

Thank you for all the suggestions.

I have tried them all however my bb core remains clogged.

Using the fine needle, did managed to puncture the hole. However for some reason the PVA filament cannot extrude at all when feeding. Also, I have had no success with the hot pull method, no PLA filament ever extrudes.

In addition I have noticed only a small part of the PLA material actually being melted under the hot and cold pull methods. i.e. only 1 to 2 mm of PLA material appears to be melting under these methods.

I have repeated the hot and cold pull together with needle puncture methods repeatedly, however still no results.

Appreciate any more suggestions.

I have avoided trying to dismantle the BB core so far.

Regards

Karam

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Hi,

Yes i contacted them. They suggested to buy a new bb core. They said "there is no ultimate repair for print cores"

I am really out of ideas, appreciate any more corrective suggestions.

Regards

Karam

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I think you did not answer this question:

"When you take out the PLA during hot-pull, is the tip melted? That is hugely important. If you have material stuck in your cold zone the hot and cold pulls will never work."

I don't understand why you cannot extrude material after you punctured the clog with a needle. To which temperature did you heat up the hot end?

Did you use polycarbonate for the hot pulls and the cold pulls?

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Hi

During hot pull, yes the pla material does melt at the tip. I must stress that only around 1mm of the tip melts. In addition when i pull it out, it aplears blunt. I.e. not sharp. There is not burn marks on it.

During hot pull i set the temp to 150 to 175 degrees.

I do not have any polycarbonate to use unfortunatly.

I am happy to send you pics of the hot pull results. My email is karambadaoui@yahoo.com.au.

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Hi

During hot pull, yes the pla material does melt at the tip. I must stress that only around 1mm of the tip melts. In addition when i pull it out, it aplears blunt. I.e. not sharp. There is not burn marks on it.

During hot pull i set the temp to 150 to 175 degrees.

I do not have any polycarbonate to use unfortunatly.

I am happy to send you pics of the hot pull results. My email is karambadaoui@yahoo.com.au.

 

That is not a high enough temp for PVA/PLA hot pull. Try setting your temps to about 210° - 220° C and then wait until it cools to about 150°C for a hot pull. Atomic or cold pull would wait for the temp until about 89°C.

Make sure you hold the Cleaning piece in place until it is about 120°C to keep it in proper contact with the material in the nozzle as it cools. It will need this bond to pull out cooked in material.

Also make sure that you place the print head in one of the corners to prevent the rods from being bent while pulling the material out. It will take pliers and a bit of strength to get it out during an Atomic pull.

Or, did you mean to say 250° - 275°C and it was just a typo? (asks the king of typos)....

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Sorry yes i meant 250 degrees (typo)

I feel there is just too much burnt material stuck inside.

As i remove the needle small amounts of burnt material comes out. I have this over a dozen times and still burnt material comes out

All out of ideas im afraid.

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keep digging. If you went that high on your temps, you probably cooked the devil out of it and it is really burned on. Time and patience. Get into the zen of the cleaning and not hurry.

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I have to correct @kmanstudios here, a hot pull with PLA is (meant to be) done at 230 degrees. Insert the plastic, wait 1-2 seconds and pull it out. The timing is of the essence here, because if you wait too long, too much of the inserted plastic was molten, and you are not able to pull the dirt out! If you wait too short, the plastic has no time to melt.

see also this support page.

So: bring the hot end to 230, and start "fishing" with hot pulls.

Please report back your result. I will help you further if necessary.

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I have to correct @kmanstudios here, a hot pull with PLA is (meant to be) done at 230 degrees.
And for that I am grateful.

You kept me from leading another person down the wrong rabbit hole. And, I should have just linked to the support page.

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Hi all,

 

I'm having similar problems with my BB core also. It's a new Ultimaker 3, with a freshly opened reel of 750g PVA fed into the machine, so cleanliness shouldn't be an issue. It was running a big job (due to take 5 days), but last night (3 days in), the BB nozzle clogged and failed to continue extruding. I have been trying unsuccessfully all day to clear it, using hot and cold PLA pulls, as per the UM3 help.

Initially, I did get some residue out, and it was almost black, so well and truly carbonised! However, the PLA I've been using has now given a cone tip as if it was clear, but it is still not extruding. I've some airbrush cleaning needles at home, so will give that a try tomorrow.

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When you are cleaning it, are you using a 'plunging' action? Like pumping the filament up and down? I have found that to be helpful during the hot pull as it seems to scrub the sides a bit.

 

I use an airbrush needle too, just be very careful to not push too far and create a flair on the nozzle tip.

 

Also, when you are cleaning the PVA out, what temp are you using? I have had to to really crank it sometimes to get the crap out.

 

Also, depending on where you are or what environment, humidity will play a larger role in the clogging than most other things. Did you hear popping, crackling and such when it was running the job?

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40 minutes ago, kmanstudios said:

When you are cleaning it, are you using a 'plunging' action? Like pumping the filament up and down? I have found that to be helpful during the hot pull as it seems to scrub the sides a bit...

I wasn't but I'll give it a try tomorrow.

 

40 minutes ago, kmanstudios said:

...

I use an airbrush needle too, just be very careful to not push too far and create a flair on the nozzle tip.

...

I'll remember that, thanks.

 

40 minutes ago, kmanstudios said:

...

Also, when you are cleaning the PVA out, what temp are you using? I have had to to really crank it sometimes to get the crap out.

...

I tended to use the default PLA temperature that Ultimaker suggested for the "hot pull". I did however try 215, and had no better luck with this.

 

40 minutes ago, kmanstudios said:

...

Also, depending on where you are or what environment, humidity will play a larger role in the clogging than most other things. Did you hear popping, crackling and such when it was running the job?

There was no popping or crackling that I noticed. As I say, it was a new reel, and was only opened when the print was started. Could it really degrade that quickly?

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Glad you solved the clog. But still interesting to know the root cause. 

The BB core should not clog, also not after many days of printing. However, a minimum flow is needed. How much PVA was in the layers before it failed? If it has to heat up the nozzle tp print a tiny bit of PVA every layer, it could burn and clog. This is however very rare.

Another option (makes more sense) is that there was another reason that there was no flow, for instance entanglement of the filament. Your clog was then the consequence of this.

 

Did you use Cura for slicing? Cura takes care that the not-used nozzle is lowered in temperature.

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Unfortunately, I wasn't near the printer when it clogged, so the I'm not sure on the exact failure mode. When I spotted that it had failed, the feed screw had stripped out the filament on the feed, so I can't confirm whether the stripped filament was as a consequence of the clog, or the clog was as a consequence of the stripped out filament.

 

The part was a very detailed model of a complete truck cab, and so yes, there may have been little bits of PVA each layer. As you say, its possible that the constant fluctuation in heat cycle for each layer, was enough to cause the material to burn slightly, and this could have contributed.

 

When removed the filament to try to resolve the issue, I did notice that about 50cm of filament leading into the bowden tube had become really brittle, with the section after this being the usual flexible PVA consistancy, so I'm not sure if this contributed. Unfortunately I binned this filament, so don't have it to hand any more.

 

Cura was used for slicing, so it should have reduced the nozzle temp as you suggested..

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