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ldaponte

BB 0.4 Nozzle clogged printing PVA

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I have a fairly new UM3E and the only issue I'm currently having is that printing PVA supports is not working well.  I'm only using Ultimaker filament and I've only printed from the same reel of PVA on the BB core.  After printing Benchy and a couple of other prints, the PVA printing from print core 2 - the BB 0.4 (extruder #2) that came with the printer, has stopped extruding material. The first time this happened I followed the printer cleaning directions from Ultimaker using Ultimaker cleaning filament.  I removed a lot of black carbonized gunk and was able to get the PVA to extrude a little.  On my last print I noticed that the PVA filament had broken near the extruder.  After more cleaning and no PVA extruding from the BB core I decided to post here.  I've been using the defaults in Cura, Cura is auto recognising the Ultimaker filament.  I took a look at replacement BB cores but at EUR 165 maybe I need to just replace the brass nozzle(?).  I expect something is out of adjustment because of the broken filament.  In the mean time, I'm getting good print quality out of the AA core (extruder #1) without supports.  What sort of performance should I expect with PVA and the BB core, what tweaks could I make to improve my experience with the PVA?  Are there any other cleaning techniques beyond the hot/cold pull to clean/fix my BB 0.4 core and how do I clean the nozzle?  Attaching photo of the current state of the core nozzle.  The AA core (extruder #1) nozzle looks like shinny brass - not sure why so much PVA material is collecting on the BB nozzle but I'm knew to this and probably making a rookie mistake.  Thanks.

 

Larry

 

1850704496_IMG_1622(1).thumb.jpg.bb106c8df3a10c96cb1d7a8345784b62.jpg
 

Edited by ldaponte

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I can only tell that I have exactly he same problem. PVA should have a density of 50% (default ws set by Cura), but is only a fraction of it. I took a picture during the printing. Hopefully someone with more experience with UM3 can give a hint?

DSC_0111.JPG

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Thanks for the reply Eric.  Your photo looks similar to what I've been able to print with PVA when it was still printing PVA at all.  Very little material at all and really not supporting anything.

 

Anyone else with PVA results to share?

 

Also, Is this the correct nozzle replacement for UM3 AA 0.4 print core?  Unless I change something I expect I'll just foul another nozzle.

 

https://www.amazon.de/Zubehör-Drucker-Ultimaker-Düse-messing/dp/B074W7LBSY/ref=sr_1_1?ie=UTF8&qid=1527025825&sr=8-1&keywords=ultimaker+nozzle

 

Thanks

 

-Larry

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How long has your PVA been open? How have you been storing it?

 

If you bend it how does it feel? There's two ways it can go bad--super flexible (humidity has gotten into it), or super brittle (too much heat).

 

Have you tried a print core cleaning? There's been very few Print Cores that have ever come my way that I haven't been able to get clean with Ultimaker Cleaning filament, Nylon, or PC. 

With clean cores and good PVA it should print reliably. Generally the only reason I have PVA fails is usually if I know I'm using marginal PVA that's been left out, but I decide to risk it anyway. 

UM2+ nozzles can be changed out. I absolutely do not recommend changing out the nozzle on your UM3 Print Core; they're fragile and not really meant to be disassembled without the right tools, though I know some people here have done it. Disassembling it puts a fairly significant risk of breaking the double heat break, because it's fragile (so that the Teflon piece can stay cool).

 

 

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Thank you for the reply!  This PVA has been open for approximately eight months.  It feels pretty bendy but I can’t remember what it was like when it was new, it’s the only reel of PVA I’ve had so don’t have enough experience to see something about it has changed except for its performance when printing which deteriorated several weeks later.  Here is a video showing the PVA elasticity 

 

https://youtu.be/tBJSi_Txuxk

 

the PVA is stored in the original ultimaker  cardboard box in my basement along with the printer and other filament.  I’m aware that humidity and temperature affect the material so I need to read up on how to control this - I think some are using big Rubbermaid comtainers. I could put up a temp and humidity sensor.

 

ive have cleaned the BB print core once before with Ultimaker cleaning filament and this procedure as documented by ultimaker went well with a few hot and cold pulls it started extruding PVA again until print after next.  Using the same cleaning filament and procedure I can not unclog the print head and the nozzle is completely occluded with carbonized material.  I don’t want to use a file as this might damage the nozzle.  Is there a solvent I should use?

 

thanks for the info on nozzle replacement.  I’ve read that it’s not recommended to disassemble the core but didn’t know this included the nozzle- will work on cleaning it somehow.

 

-Larry

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I would store open PVA in a bag or plastic container with silica packs. It's the best way to keep the moisture out.

Generally if you can tie a knot in the PVA, you're risking the PVA tying itself in a knot around your feeder. (This photo is from a particularly bad incident.)

2017-04-04-PHOTO-00000725.thumb.jpg.6b816d5e28bd0b56ac4dab7ba8fde355.jpg

 

I keep meaning to make a video showing good PVA and both ways PVA can go bad. Do you have PLA? I generally find bending good PVA feels like bending PLA--you can break it when you bend it, but it doesn't just snap unexpectedly.


I wouldn't recommend a file, but if you have a thin needle, you can try inserting that from the underside of the print core when it's hot. It might break up burnt material. Sometimes the hot and cold pulls have to be repeated multiple times to get it clear. The needle can help.

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Thanks!  Big zip locks and desiccant bags and a new reel of Ultimaker PVA is on the way.  Will try to get this core cleaned and try again - will try your needle method.  @fbrc8-eri, any reason to change the default Cura PVA settings?

 

-Larry

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Having had some problems myself with PVA as I learned to use it, I found out that you can also get rid of a clogging by letting it heat up for a while, like 30 minutes or something then doing hot pulls. That way, the PVA heats up to the core and melts nicely, and what's sticking to the inside of the core turns to charcoal and comes off more easily when you do some hot pulls afterwards. Worked with PLA clogging as well in my experience.

 

You have to force it until you see the burnt part extrudes some, but the UM3/E is quite resilient so you can apply some muscle without fear of breaking it. If the whole printcore assembly is on the front-right corner as prescribed in the manual.

 

I'm personally wary of the needle method because you can inadvertently damage the nozzle if the needle is a bit too thick or you twist it the wrong way and scratch the inside of the core.

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Hi guys,

 

Thanks for all  your comments and tips. I really learn a lot in this forum.

What I discovered as a solution for the PVA is, that since I reduced the printing speed of nozzle-2 drastically (to 35 in stead of 70), and left all the other parameters on Cura's default,  that gave a fantastic improvement in the results. Although the total printing hours of my prototype increased by 9 hours!!

But it seems worth it.

 

Btw: I only use Ultimaker filament, and my PVA was brand new.

In Nozzle-1 I used nylon for the first time. Results are quite good.

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I use most of the Cura PVA settings on default--if you're not using 3.3.1, I do recommend updating because I think it's pretty dialed in.

 

Things I do usually change:

* PVA brim instead of PLA brim--if you can have your PVA printing directly to glass/PVA it will be sturdier than trying to print it on top of PLA
* Horizontal Support Expansion--default is 3mm, but I usually like to look at the print in Layer view and see where the supports fall. If I can make the supports connect to each other/be more sturdy by increasing the horizontal expansion a little, I go ahead and do it.

* Turn on Prime Tower--some of the earlier versions of Cura, the PLA/PVA adhesion on the prime tower was not as good as it could have been. However, 3.3.1 I haven't had any issues with the PLA/PVA prime towers.

* Print PVA slow. I think 35mm/s sounds pretty good. 

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I can only confirm the advantage of a PVA brim instead of the PLA brim. This should be a default in Cura. @Tomhe / @KristelB what do you think?

I usually don't change the horizontal expansion on the support in order to make it sturdier but the support join distance.

I also find the prime towers for two different materials still a bit thin. I increase the thickness to 3-4mm.

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12 hours ago, Dim3nsioneer said:

I can only confirm the advantage of a PVA brim instead of the PLA brim. This should be a default in Cura. @Tomhe / @KristelB what do you think?

I usually don't change the horizontal expansion on the support in order to make it sturdier but the support join distance.

I also find the prime towers for two different materials still a bit thin. I increase the thickness to 3-4mm.

 

I would LOVE to see PVA brim as the default when printing PLA/PVA. Please?

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