Thanks for reply.
Yes I used cura 4.9, in fact before start print I seen the PVA not in correct position, but when the PVA was arrived in position not worked very well.
I thinks that there are 2 problems. The first the bug on cura 4.9 and the second the print core B-B
Yes I agree. To fix the second problem it could be either partially clogged or the PVA may have absorbed too much water. Just 2 days on the back of the printer is sometimes enough to "ruin" the filament.
To unclog a BB core read about hot and cold pulls. There are instructions on the display of what to do and guidance.
To restore PVA read about how to do that. I use the heated bed to restore a spool of PVA. It can take just hours or days depending how much filament you need to restore (whole spool or outer bits). Be careful not to overheat - just read what other people have written.
Yes, I think that the PVA have absorbed a lot of water though the spool is staying always in material station.
I will order a vacuum kit for PVA and other material. I read in this forum that is more correct put in the material station the PVA material only if will be used.
For clean the print core B-B
I see the message that the S5 tell me, and tell that I can used two tipe of material or PLA or clean filament, but I remember that the printer vendor was very clear that the B-B print core is only made for PVA. It is not possible to extrude the PLA otherwise it will be ruined.
The BB core can print PLA just fine - there are no issues except you will get more stringing in your print. No harm to the BB core.
Anyway for cleaning the core it's definitely fine to use PLA. Or PVA. I'd remove the bowden tube on the top of the head and insert manually. You slide out the white clip and push down on the collet while pulling out the bowden. The entire cleaning process seems involved the first time but is super easy the second time. There are tons of videos about cold pulls on youtube - you don't have to watch an Ultimaker specific one. When you do it right the filament will come out in the shape of the interior of the nozzle - perfectly. Even the tiny final tube/passage.
If you see black gunk then that's good - you are removing that gunk from the BB core.
Oh and I wouldn't get a vacuum chamber for the PVA. You can make it too dry if you go too far. Just use the printer itself. Leave the spool on the print bed with a blanket over it set to 60C. You might need many inches of blankets (otherwise the top of the spool may only be at say 40C). Leave it like that several nights in a row or for a few days to dry it out nicely.
The material station should be able to keep the PVA dry just fine - but I don't have a MS so I don't speak from experience. But I don't think the MS can dry PVA that is already wet.
If you only need a few meters of PVA then I unspool a few meters and put that directly on the bed with the spool on top and a towel/blanket over all that and you can restore PVA in just a few hours at 60C.
Overly dry PVA gets extra brittle (I'm told - I've never experienced this - I've never dried my PVA too much).
By the way, Nylon is the other filament that absorbs water like crazy. Those are the worst two (nylon, pva). PLA doesn't seem to have an issue (I suspect you can store it underwater for all it seems to care). The only other filament I've had get wet is some really old CPE that I left sitting out for a few years with no dessicant. Also easily dried on the heated bed.
Thanks @ gr5 for your help. Now I have bought the vacuum bags for spools. The PVA and Nylon are in vacuum packed.
Next time I try to clean the print core B-B, because now I'm using the breakaway Ultimaker with A-A print core.
Again, I don't think vacuum bags will help. You need dessicant. Like this:
Also once you get water in the filament, no amount of vacuum or dessicant will help - you need to heat it as I describe above.
1
Ok, I understand, in fact I put the spool in a vacuum bag with a silica gel bag.
Before reusing the spool, I will put it on the heat bed.
Thanks for your valuable help.
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gr5 2,234
Did you upgrade to cura 4.9? If so then this is a known bug where the right hand extruder retracts too much before printing. I think a 4.9.1 release is imminent (not sure). A quick fix might be to lift the lever on the right feeder and slide the PVA further in just before it starts printing - not sure if this will work. Or go back to cura 4.8 until 4.9.1 comes out.
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